grosz & sidner (1986)
DESCRIPTION
---TRANSCRIPT
7/17/2019 Grosz & Sidner (1986)
http://slidepdf.com/reader/full/grosz-sidner-1986 1/30
A T T E N T I O N , I N T E N T I O N S , A N D T H E S T R U C T U R E O F D I S C O U R S E
B a r b a r a J . G r o s z
A r t i f i c i a l I n t e l l i g e n c e C e n t e r a n d
C e n t e r f o r t h e S t u d y o f L a n g u a g e a n d I n f o r m a t i o n
S R I I n t e r n at i o n a l
M e n l o P a r k, C A 9 4 0 2 5
C a n d a c e L . S i d n e r
B B N L a b o r a t o r i e s I n c .
C a m b r i d g e , M A 0 2 2 3 8
I n t h i s p a p e r w e e x p l o r e a n e w t h e o r y o f d i s c o u r s e s t r u c t u r e t h a t s t r e s s e s t h e r o l e o f p u r p o s e a n d
p r o c e s s i n g i n d i s c o u r se . I n t h is t h e o r y , d i s c o u r s e s t r u c t u r e i s c o m p o s e d o f t h r e e s e p a r a t e b u t i n t e r r e -
l a t e d c o m p o n e n t s : t h e s t r u c t u r e o f t h e s e q u e n c e o f u t t e r a n c e s ( c a l l e d t h e l i n g u i s t i c s t r u c t u r e ) , a s t r u c -
t u r e o f p u r p o s e s ( c a l l e d t h e i n t e n t i o n a l s t r u c t u r e ) , a n d t h e s t a t e o f f o c u s o f a t t e n t i o n ( c a l l e d t h e
at ten t ion a l s ta te ) . T h e l i n g u i s t i c s t r u c t u r e c o n s i s t s o f s e g m e n t s o f t h e d i s c o u r s e i n t o w h i c h t h e u t t e r -
a n c e s n a t u r a l ly a g g r e g a t e . T h e i n t e n t io n a l s t r u c t u r e c a p t u r e s t h e d i s c o u r s e - r e l e v a n t p u r p o s e s ,
e x p r e s s e d i n e a c h o f t h e l in g u is t ic s e g m e n t s a s w e ll a s r e l a t io n s h i p s a m o n g t h e m . T h e a t t e n t i o n a l s t a t e
i s a n a b s t r a c t i o n o f t h e f o c u s o f a t t e n t i o n o f t h e p a r t i c i p a n t s a s t h e d i s c o u r s e u n f o ld s . T h e a t t e n t i o n a l
s t a t e , b e i n g d y n a m i c , r e c o r d s t h e o b j e c t s , p r o p e r t i e s , a n d r e l a t i o n s t h a t a r e s a l i e n t a t e a c h p o i n t o f t h e
d i s c o u r s e . T h e d i s t i n c ti o n a m o n g t h e s e c o m p o n e n t s i s e s s e n t i a l t o p r o v i d e a n a d e q u a t e e x p l a n a t i o n o f
s u c h d i s c o u r s e p h e n o m e n a a s c u e p h r a s e s , r e f e r r i n g e x p r e s s i o n s , a n d i n t e r r u p t i o n s .
T h e t h e o r y o f attent ion , in tent ion , a n d a g g r e g a t i o n o f u t t e r a n c e s i s i l l u s t r a t e d i n t h e p a p e r w i t h a
n u m b e r o f e x a m p l e d i s c o u r se s . V a r i o u s p r o p e r t i e s o f d is c o u r s e a r e d e s c r i b e d , a n d e x p l a n a t i o n s f o r t h e
b e h a v i o r o f c u e p h r a s e s , r e f e r r i n g e x p r e s s i o n s , a n d i n t e r r u p t i o n s a r e e x p l o r e d .
T h i s t h e o r y p r o v i d e s a f r a m e w o r k f o r d e s c r i bi n g t h e p r o c e s s i n g o f u t t e r a n c e s i n a d i s c o u rs e .
D i s c o u r s e p r o c e s s i n g r e q u i r e s r e c o g n i z i n g h o w t h e u t t e r a n c e s o f t h e d i s c o u r s e a g g r e g a t e i n t o s e g m e n t s ,
r e c o g n i z in g t h e i n t e n t i o n s e x p r e s s e d i n t h e d i s c o u r s e a n d t h e r e l a t i o n s h ip s a m o n g i n te n t i o n s , a n d t r a c k -
i n g t h e d i s c o u rs e t h r o u g h t h e o p e r a t i o n o f t h e m e c h a n i s m s a s s o c i a t e d w i t h a t t e n t i o n a l s t a t e . T h i s
p r o c e s s i n g d e s c r i p t i o n s p e c i f i e s i n t h e s e r e c o g n i t i o n t a s k s t h e r o l e o f i n f o r m a t i o n f r o m t h e d i s c o u r s e
a n d f r o m t h e p a r t i c i p a n t s ' k n o w l e d g e o f t h e d o m a i n .
1 INTRODUCTION
p a p e r p r e s e n t s t h e b a si c e l e m e n t s o f a c o m p u t a -
t h a t s i m p f if i e s a n d
w o r k . B y s p e c i fy i n g t h e b a s i c
u t t e r a n c e i n t h e d i s c o u rs e m u s t b e r e l a te d .
A n a c c o u n t o f d i s c o u r s e s t r u c t u r e i s c l o s e l y r e l a t e d t o
t w o q u e s t i on s : W h a t i n d i v i d u a t e s a d i s c o u r s e ? W h a t
m a k e s i t c o h e r e n t ? T h a t i s , f a c e d w i t h a s e q u e n c e o f
u t t e ra n c e s , h o w d o e s o n e k n o w w h e t h e r t h e y c o n s t it u t e a
s i n gl e d i sc o u r s e , s e v e r a l ( p e r h a p s i n t e r l e a v e d ) d i s c o u r s e s ,
o r n o n e ? A s w e d e v e l o p i t, t h e t h e o r y o f d i s c o u rs e s t r u c -
t u r e w i l l b e s e e n t o b e i n t i m a t e l y c o n n e c t e d w i t h t w o
n o n l i ng u i s ti c n o ti o n s : i n t e n t io n a n d a t t e n t io n . A t t e n t i o n
i s a n e s s e n t i a l f a c t o r i n e x p l i c a t i n g t h e p r o c e s s i n g o f
u t t e r a n c e s i n d i s c o u r se . I n t e n t i o n s p l a y a p r i m a r y r o l e i n
e x p l a i n i n g d i s c o u r s e s t r u c t u r e , d e f i n i n g d i s c o u r s e c o h e r -
e n c e , a n d p r o v i d i n g a c o h e r e n t c o n c e p t u a l i z a t i o n o f t h e
t e r m d i s c o u r s e i t s e l f .
h t 1 9 8 6 b y t h e A s s o c i a t i o n f o r C o m p u t a t i o n a l L i n g u i s t i c s. P e r m i s s i o n t o c o p y w i t h o u t f e e a l l o r p a r t o f t h i s m a t e r i a l is g r a n t e d p r o v i d e d t h a t
CL r e f e r e n c e a n d t h i s c o p y r i g h t n o t i c e a r e in c l u d e d o n t h e f i rs t p a ge . T o c o p y
e s a f e e a n d / o r s p e c if i c p e r m i s s io n .
0 3 6 2 - 6 1 3 X / 8 6 / 0 3 0 1 7 5 - 2 0 4 5 0 3 . 0 0
n a l L i n g ui s ti c s , V o l u m e 1 2 , N u m b e r 3 , ~ l u l y - S e pt e m b e r 1 9 8 6 1 7 5
7/17/2019 Grosz & Sidner (1986)
http://slidepdf.com/reader/full/grosz-sidner-1986 2/30
B a r b a r a J . G r o s z a n d C a n d a c e L . S i d n e r A t t e n t i o n , I n t e n t i o n s , a n d t h e S t r u c t u r e o f Dis
T h e t h e o r y i s a f u r t h e r d e v e l o p m e n t a n d i n t e g r a t i o n o f
t w o l i n e s o f r e s e a r c h : w o r k o n f o c u s i n g i n d i s c o u r s e
( G r o s z 1 9 7 8a , 1 9 7 8 b , 1 9 8 1 ) a n d m o r e r e c e n t w o r k o n
i n t e n t i o n r e c o g n i t i o n i n d i s c o u r s e ( S i d n e r a n d I s r a e l
1 9 8 1 ; S i d n e r 1 9 8 3; 1 9 8 5 ; A l l e n 1 9 8 3 , L i t m a n 1 9 8 5 ;
P o l l a c k 1 9 8 6 ) . O u r g o a l h a s b e e n t o g e n e r a l i z e t h e s e
c o n s t r u c t s p r o p e r l y t o a w i d e r a n g e o f d i s c o u r s e t y p e s .
G r o s z ( 1 9 7 8 a ) d e m o n s t r a t e d t h a t t he n o t i o n s o f fo c u s in g
a n d t a s k s t r u c t u r e a r e n e c e s s a r y f o r u n d e r s t a n d i n g a n d
p r o d u c i n g t a s k - o r i e n t e d d i a l og u e . O n e o f t h e m a i n
g e n e r a l i z a t i o n s o f p r e v i o u s w o r k w i l l b e t o s h o w t h a t
d i s c o u r s e s a r e g e n e ra l l y i n s o m e s e n s e t a s k - o r i e n t e d ,
b u t th e ki n d s o f t a s k s t h a t c a n b e e n g a g e d in a r e q u i t e
v a r i e d - s o m e a r e p h y s i c a l, s o m e m e n t a l , o t h e r s l i n g u is -
t ic . C o n s e q u e n t l y , t he t e r m t a s k i s m i s l e a d i n g ; w e
t h e r e f o r e w i l l u s e t h e m o r e g e n e r a l t e r m i n o l o g y o f
in tent ions
( e .g . , w h e n s p e a k i n g o f d i s c o ur s e p u r p o s e s ) f o r
m o s t o f w h a t w e s a y .
O u r m a i n t h e s i s is th a t t h e s t r u c t u r e o f a n y d i s c o u r s e i s
a c o m p o s i t e o f t h r e e d i s t in c t b u t i n t e r a c t i n g c o m p o n e n t s :
• t h e s t r u c t u r e o f t h e a c t u a l s e q u e n c e o f u t t e r a n c e s i n t h e
d i s c o u r s e ;
• a s t r u c t u r e o f i n t e n t i o n s ;
• a n a t t e n t i o n a l s t a t e .
T h e d i s t i n c t io n a m o n g t h e s e c o m p o n e n t s i s e s s e n t i a l t o
a n e x p l a n a t i o n o f i n t e r r u p t i o n s ( s e e S e c t i o n 5 ) , a s w e l l a s
t o e x p l a n a t i o n s o f t h e u s e o f c e r t a i n t y p e s o f r e f e r r i n g
e x p r e s s i o n s ( s e e S e c t i o n 4 . 2 ) a n d v a r i o u s o t h e r
e x p r e s s i o n s t h a t a f f e c t d i s c o u r s e s e g m e n t a t i o n a n d s t r u c -
t u r e ( s e e S e c t i o n 6 ) . M o s t r e l a t e d w o r k o n d is c o u r s e
s t r u c t u r e ( in c l u d in g R e i c h m a n - A d a r 1 9 8 4 , L i n d e 1 9 7 9 ,
L i n d e a n d G o g u e n 1 9 7 8 , C o h e n 1 9 8 3 ) f a i ls t o d i s ti n -
g u i s h a m o n g s o m e ( o r , i n s o m e c a s e s , a l l ) o f t h e s e
c o m p o n e n t s . A s a r e s u lt , s i g n if i c a n t g e n e r a l i z a t i o n s a r e
l o s t , a n d t h e c o m p u t a t i o n a l m e c h a n i s m s p r o p o s e d a r e
m o r e c o m p l e x t h a n n e c e s s a r y . B y c a r e f u l l y d i s t in g u i s h -
i n g t h e s e c o m p o n e n t s , w e a r e a b l e t o a c c o u n t f o r s i g n i f -
i c a n t o b s e r v a t i o n s i n t h i s r e l a t e d w o r k w h i l e s i m p l i f y i n g
b o t h t h e e x p l a n a t i on s g i v e n a n d c o m p u t a t i o n a l m e c h -
a n i s m s u s e d .
I n a d d i t i o n t o e x p l i c a t i n g t h e s e l i n g u i s t i c p h e n o m e n a ,
t h e t h e o r y p r o v i d e s a n o v e r a l l f r a m e w o r k w i t h i n w h i c h t o
a n s w e r q u e s t i o n s a b o u t t h e r e l e v a n c e o f v a r i o u s
s e g m e n t s o f d i s c o u r s e t o o n e a n o t h e r a n d t o t h e o v e r a l l
p u r p o s e s o f t h e d i s c o u r s e p a r t i c i p a n t s . V a r i o u s p r o p e r -
t i e s o f t h e i n te n t i o n a l c o m p o n e n t h a v e i m p l i c a t i o n s fo r
r e s e a r c h i n n a t u r a l - l a n g u a g e p r o c e s s i n g in g e n e r a l . I n
p a r t i c u l a r , t h e i n t e n t i o n s t h a t u n d e r l i e d i s c o u r s e a r e s o
d i v e r s e t h a t a p p r o a c h e s t o d i s c o u r s e c o h e r e n c e b a s e d o n
s e l e c t in g d i s c o u r s e r e l a t i o n s h i p s f r o m a f i x e d s e t o f a l t e r -
n a t i v e r h e t o r i c a l p a t t e r n s ( e .g . , H o b b s 1 9 7 9 , M a n n a n d
T h o m p s o n 1 9 8 3 , R e i c h m a n 1 9 8 1 ) a r e u n li k e l y t o s u f f ic e .
T h e i n t e n t i o n a l s t r u c t u r e i n t r o d u c e d i n th i s p a p e r
d e p e n d s i n s t e a d o n a s m a l l n u m b e r o f s t r u c t u r a l r e l a t i o n s
t h a t c a n h o l d b e t w e e n i n t e n t i o n s . T h i s s tu d y a l s o r e v e a l s
s e v e r a l p r o b l e m s t h a t m u s t b e c o n f r o n t e d i n e x p a n d i n g
s p e e c h - a c t - r e l a t e d t h e o r i e s ( e . g . , A l l e n a n d P e r r a u l t
1 9 8 0, C o h e n a n d L e v e s q u e 1 9 8 0 , A l l e n 1 9 8 3 ) f r o m
c o v e r a g e o f i n d i v i d u a l u t t e r a n c e s t o c o v e r a g e o f e x t e
s e q u e n c e s o f u t t e r a n c e s i n d is c o u r s e .
A l t h o u g h a d e f i n it i o n o f d i s c o u r s e m u s t a w a i t f u
d e v e l o p m e n t o f t h e t h e o r y p r e s e n t e d i n th is p a p e r ,
p r o p e r t ie s o f th e p h e n o m e n a w e w a n t t o e x p la i n m u
s p e c i f i e d n o w . I n p a r t i c u l a r , w e t a k e a d i sc o u r s e t o
p i e c e o f l a n g u a g e b e h a v i o r t h a t t y p i c a l l y i n v o l v e s m
p l e u t t e r a n c e s a n d m u l t i pl e p a r t i c i p a n t s . A d is c o
m a y b e p r o d u c e d b y o n e o r m o r e o f t h e s e p a r t i c ip a n
s p e a k e r s o r w r i te r s ; t h e a u d i e n c e m a y c o m p r i s e o n
m o r e o f t h e p a r t i c i p a n t s a s h e a r e r s o r r e a d e r s . B e c
i n m u l t i - p a r t y c o n v e r s a t i o n s m o r e t h a n o n e p a r t i c
m a y s p e a k ( o r w r i te ) d i f f e r e n t u t t e r a n c e s w i t h
s e g m e n t , t h e t e r m s s p e a k e r a n d h e a r e r d o n o t d i f f
t i a t e t h e u n i q u e r o l e s t h a t t h e p a r t i c i p a n t s m a i n t a i n
s e g m e n t o f a c o n v e r s a t i o n . W e w il l t h e r e f o r e u s
t e r m s i n i t i a t i n g
conversat ional part ic ipant
( I C P ) a n d
conversat ional part ic ipant s) OCP ) t o d i s t i n g u i s h t h e
a t o r o f a d i s c o u r s e s e g m e n t f r o m i t s o t h e r p a r t i c i p
T h e I C P s p e a k s ( o r w r i t e s ) t h e f i r s t u t t e r a n c e
s e g m e n t , b u t a n O C P m a y b e t h e s p e a k e r o f s o m e s u
q u e n t u t t e r a n c e s . B y s p e a k i n g o f I C P s a n d O C P s , w
h i g h li g h t t h e p u r p o s i v e a s p e c t o f d i s c o u r s e . W e w i
t h e t e r m s speaker a n d hearer o n l y w h e n t h e p a r t i
s p e a k i n g / h e a r i n g a c t i v i t y i s i m p o r t a n t f o r t h e p o i n t
m a d e .
I n m o s t o f t h i s p a p e r , w e w i l l b e c o n c e r n e d
d e v e l o p i n g a n a b s t r a c t m o d e l o f d i s c o u r s e s t r u c t u r
p a r t i c u la r , t h e d e f i n i t i o n s o f t h e c o m p o n e n t s w i l l a b s
a w a y f r o m t h e d e t a i ls o f t h e d i s c o u r s e p a r t i c i p
W h e t h e r o n e c o n s t r u c t s a c o m p u t e r s y s t e m t h a t
p a r t i c i p a t e i n a d i s c o u r s e ( i . e . , o n e t h a t is a l a n g
u s e r ) o r d e f i n e s a p s y c h o l o g i c a l t h e o r y o f l a n g u a g e
t h e t a s k w i ll r e q u ir e t h e a p p r o p r i a t e p r o j e c t i o n o f
a b s t r a c t m o d e l o n t o p r o p e r t i e s o f a l a n g u a g e u s e r ,
s p e c i f i c a t i o n o f a d d i t io n a l d e t a i l s ( e . g ., s p e c i f y i n g m
r y f o r li n g ui s ti c s t r u c t u r e , m e a n s f o r e n c o d i n g a t t e n t
s t a t e , a n d a p p r o p r i a t e r e p r e s e n t a t i o n s o f i n t e n t
s t r u c t u r e ) . W e d o , h o w e v e r , a d d r e s s o u r s e l v e s d i r e c
c e r t a i n p r o c e s s i n g i s s u e s t h a t a r e e s s e n t i a l t o t h e c o
t a t i o n a l v a l i d i ty o f t h e [ a b s t r a c t ] m o d e l a n d t o i t s u t
t i o n f o r a l a n g u a g e - p r o c e s s i n g s y s t e m o r p s y c h o l o
t h e o r y .
F i n a l ly , i t i s i m p o r t a n t t o n o t e t h a t a l t h o u g h d i s c
mean ing
i s a s i g n i f i c a n t , u n s o l v e d p r o b l e m , w e w i l
a d d r e s s i t i n t h is p a p e r . A n a d e q u a t e t h e o r y o f d i s c
m e a n i n g n e e d s t o r e s t a t l e a s t p a r t i a l l y o n a n a d e q
t h e o r y o f d i s c o u r s e s t r u c t u re . O u r c o n c e r n i s w i t h p r
i n g t h e l a t t e r .
T h e n e x t s e c t i o n e x a m i n e s t h e b a s i c t h e o r
d i s c o u r s e s tr u c t u r e a n d p r e s e n t s a n o v e r v i e w o f e a
t h e c o m p o n e n t s o f d is c o u r s e s t r u c t u r e . S e c t i o
a n a l y z e s t w o s a m p l e d i s c o u r s e s - a w r i t t e n t e x t a
f r a g m e n t o f t a s k - o r i e n t e d d i al o g ue - f r o m t h e p e r
t i v e o f t h e t h e o r y b e i n g d e v e l o p e d ; t h e s e t w o e x a m
a r e a l s o u s e d t o i l l u s t r a t e v a r i o u s p o i n t s i n t h e r e m a
o f t h e p a p e r . S e c t i o n 4 i n v e s t i g a t e s v a r i o u s p r o c e
176
C o m p u t a t i o n a l L i n g u i s t i c s , V o l u m e 1 2 , N u m b e r 3 , J u l y - S e p t e m b e r
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J . G r o s z a n d C a n d a c e L . S i d n e r A t t e n t i o n , I n t e n t i o n s , a n d t h e S t r u c t u r e o f D i s c o u r s e
e s t h a t th e t h e o r y r a i s e s. T h e f o l l o w i n g t w o s e c t i o n s
e o f th e d i s c o u r s e s t r u c t u re c o m p o n e n t s
S e c t i o n 7 d e s c r i b e s th e g e n e r a l i z a t i o n
e l t o d i s c o u r s e - l e v e l i n t e n t io n s , e s t a b -
t h e o r y .
2 T H E B A S IC T H E O R Y
a l i n g u is t i c s tr u c t u r e , a n i n t e n t i o n a l s t r u c -
a n d a n a t t e n t i o n a l s ta t e . T h e s e t h r e e c o n s t i t u e n t s
a d i s c o u rs e . U t t e r a n c e s - t h e a c t u a l s a y i n g
a r e t h e l i n g u is t i c s t r u c t u r e ' s b a s i c e l e m e n t s . I n t e n t i o n s
s t r u c tu r e . A t t e n t i o n a l s t a t e c o n t a i n s in f o r m a t i o n
h a t a r e m o s t s a l i e n t a t a n y g i v e n : p o i n t . I t is
a n t s ; i t s e r v e s t o s u m m a r i z e i n f o r m a t i o n f r o m
T o g e t h e r t h e t h r e e c o n s t i t u e n t s o f d i sc o u r s e s t r u c t u r e
t h e i n f o r m a t i o n n e e d e d b y t h e C P s t o d e t e r m i n e
i n e s s e n c e , e n a b l i n g t h e m t o f i g u r e o u t w h y i t
d a n d w h a t i t m e a n s . T h e c o n t e x t p r o v i d e d b y
a n a d d i t io n a l p u r p o s e : n a m e l y , i t f u r n i s h e s
2.1 LINGUI STIC STRUCTU RE
f i rs t c o m p o n e n t o f d is c o u r s e s t r u c t u r e i s t h e s t r u c -
1 J u s t a s t h e w o r d s i n a s i n g le s e n t e n c e f o r m
y a g g r e g a t e d i n t o d is c o u rs e s e g m e n ts . T h e u t t e r -
a r r o l e s w i t h r e s p e c t t o t h a t s e g m e n t . I n a d d i t i o n ,
r e s p e c t t o t h e o v e r a l l d i s c o u rs e . A l t h o u g h
m a y b e i n t h e s a m e d i s c o u r s e
T h e f a c t o r i n g o f d i s c o u r s e s i n to s e g m e n t s h a s b e e n
o b s e r v e d a c r o s s a w i d e r a n g e o f d i s c o u r s e t y p e s . G r o s z
( 1 9 7 8 a ) s h o w e d t h is f o r t a s k - o r i e n t e d d i a l o g ue s . L i n d e
( 1 9 7 9 ) f o u n d i t va l i d f o r d e s c r i p t i o n s o f a p a r t m e n t s ;
L i n d e a n d G o g u e n ( 1 9 7 8 ) d e s c r i b e s u c h s t r u c t u r i n g i n
t h e W a t e r g a t e t ra n s c ri p ts . R e i c h m a n - A d a r ( 1 9 8 4 )
o b s e r v e d i t i n i n f o r m a l d e b a t e s , e x p l a n a t i o n s , a n d t h e r a -
p e u t i c d i s c o u r se . C o h e n ( 1 9 8 3 ) f o u n d s im i l a r s t r u c t u r e s
i n e s s a y s i n r h e t o r i c a l t e x ts . P o l a n y i a n d S c h a ( 1 9 8 6 )
d i s c u s s t h i s f e a t u r e o f n a r r a t i v e s .
A l t h o u g h d i f f e r e n t r e s e a r c h e r s w i t h d i f f e r e n t t h e o r i e s
h a v e e x a m i n e d a v a r i e t y o f d is c o u r s e t y p e s a n d f o u n d
d i s c o u r s e - l e v e l s e g m e n t a t i o n , t h e r e h a s b e e n v e r y l i tt le
i n v e s t i g a ti o n o f t h e e x t e n t o f a g r e e m e n t a b o u t w h e r e t h e
s e g m e n t b o u n d a r i e s li e. T h e r e h a v e b e e n n o p s y c h o l o g -
i c a l s t u d i e s o f t h e c o n s i s t e n c y o f r e c o g n i t i o n o f s e c t i o n
b o u n d a ri e s . H o w e v e r , M a n n ( M a n n e t a l. 1 9 75 ) a s k e d
s e v e r a l p e o p l e t o s e g m e n t a s e t o f d ia l o g u e s . H e h a s
r e p o r t e d [ p e r s o n a l c o m m u n i c a t i o n ] t h a t h i s s u b j e c t s
s e g m e n t e d t h e d i s c o u r se s a p p r o x i m a t e l y t h e s a m e ; t h e i r
d i s a g r e e m e n t s w e r e a b o u t u t t e r a n c e s a t t h e b o u n d a r i e s o f
s e g m e n t s . 2 S e v e r a l s t u d i e s o f s p o n t a n e o u s l y p r o d u c e d
d i s c o u r s e s p r o v i d e a d d i t i o n a l e v i d e n c e o f t h e e x i s t e n c e o f
s e g m e n t b o u n d a r i e s , a s w e l l a s s u g g e s t in g s o m e o f t h e
l i ng u i st i c c u e s a v a i l a b le f o r d e t e c t i n g b o u n d a r i e s . C h a f e
( 1 9 7 9 , 1 9 8 0 ) f o u n d d i f f e r e n c e s i n p a u s e l e n g t h s a t
s e g m e n t b o u n d a ri e s . B u t t e r w o r t h ( 1 9 7 5 ) f o u n d s p e e c h
r a t e d i f f e r e n c e s t h a t c o r r e l a t e d w i t h s e g m e n t s ; s p e e c h
r a t e i s s l o w e r a t s t a r t o f a s e g m e n t t h a n t o w a r d t h e e n d .
T h e l i n g u i s t i c s t r u c t u r e c o n s i s t s o f t h e d i s c o u r s e
s e g m e n t s a n d a n e m b e d d i n g r e l a t i o n s h i p t h a t c a n h o l d
b e t w e e n t h e m . A s w e d i s c u s s i n S e c t i o n s 2 . 2 a n d 5 , t h e
e m b e d d i n g r e l a t i o n s h i p s a r e a s u r f a c e r e f l e c t i o n o f
r e l a t i on s h i p s a m o n g e l e m e n t s o f t h e i n t e n t i o n a l s t r u c tu r e .
I t i s i m p o r t a n t t o r e c o g n i z e t h a t t h e l i n g u i s ti c s t r u c t u r e i s
n o t s t r ic t l y d e c o m p o s i t i o n a l . A n i n d i v id u a l s e g m e n t m a y
i n c lu d e a c o m b i n a t i o n o f s u b s e g m e n t s a n d u t t e r a n c e s
o n l y i n th a t s e g m e n t ( a n d n o t m e m b e r s o f a n y o f i t s
e m b e d d e d s u b s e g m e n t s ) . B o t h o f t h e e x a m p l e s i n S e c ti o n
3 e x h i b i t s u c h n o n s t r i c t d e c o m p o s i t i o n a l i t y . B e c a u s e t h e
l i n g u i s t i c s t r u c t u r e i s n o t s t r i c t l y d e c o m p o s i t i o n a l , v a r i o u s
p r o p e r t i e s o f t h e d i s c o u r s e ( m o s t n o t a b l y t h e i n t e n t i o n a l
s t r u c t u r e ) a r e f u n c t i o n s o f p r o p e r t i e s o f i n d i v i du a l u t t e r -
a n c e s a n d p r o p e r t i e s o f s e g m e n t s .
T h e r e i s a t w o - w a y i n t e r a c t i o n b e t w e e n t h e d i s c o u r s e
s e g m e n t s t r u c t u r e a n d t h e u t t e r a n c e s c o n s t i t u t i n g t h e
d i s c o u r se : l in g u is t ic e x p r e s s i o n s c a n b e u s e d t o c o n v e y
i n f o r m a t i o n a b o u t t h e d i s c o u r s e s t r u c t u r e ; c o n v e r s e l y ,
t h e d i s c o u r s e s t r u c t u r e c o n s t r a i n s t h e i n t e r p r e t a t i o n o f
e x p r e s s i o n s ( a n d h e n c e a f f e c t s w h a t a s p e a k e r s a y s a n d
h o w a h e a r e r w i l l i n t e r p r e t w h a t i s s a i d ). N o t s u r p r i s i n g -
l y , l i n g u i s t i c e x p r e s s i o n s a r e a m o n g t h e p r i m a r y i n d i c a -
t o r s o f d i s c o u r s e s e g m e n t b o u n d a r i e s . T h e e x p l ic i t u s e o f
c e r t a i n w o r d s a n d p h r a s e s ( e . g . ,
in the f i rs t p lace)
a n d
m o r e s u b t l e c u e s , s u c h a s i n t o n a t i o n o r c h a n g e s i n t e n s e
a n d a s p e c t , a r e i n c l u d e d i n t h e r e p e r t o i r e o f l i n g u i s t i c
d e v i c e s t h a t f u n c t i o n , w h o l l y o r i n p a r t , t o i n d i c a t e t h e s e
1986 177
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Barbara J . Grosz and Candace L . S idner At tent ion , In tent ions , and the S tructure of Disc
boundaries (Grosz 1978a, Reichman-Adar 1984, Cohen
1983, Polanyi and Scha 1983, Hirschberg and Pierre-
humbert 1986). Reichm an (1981) discusses some words
that function in this way and coined the term
c l u e w o r d s .
We will use the term
c u e p h r a s e s
to generalize on her
observation as well as many others because each one of
these devices cue the hearer to some change in the
discourse structure.
As discussed in Section 6, these linguistic boundary
markers can be divided according to whether they explic-
itly indicate changes in the intentional structure or in the
attentional state of the discourse. The differential use of
these linguistic markers provides one piece of evidence
for considering these two components to be distinct.
Because these linguistic devices function explicitly as
indicators of discourse structure, it becomes clear that
they are best seen as providing information at the
discourse level, and not at the sentence level; hence,
certain kinds of questions (e.g., about their contribution
to the truth conditions of an individual sentence) do not
make sense. For example, in the utterance
I nc iden ta l l y ,
Jane swims every day ,
the
inc iden ta l l y
indicates an inter-
ruption of the main flow of discourse rather than affect-
ing in any way the meaning of
Jane swims every day .
Jane's swimming every day could hardly be fortuitous.
Just as linguistic devices affect structure, so the
discourse segmentation affects the interpretation of
linguistic expressions in a discourse. Refe rrin g
expressions provide the primary example of this effect. 3
The segmentation of discourse constrains the use of
referring expressions by delineating certain points at
which there is a significant change in what entities
(objects, properties, or relations) are being discussed.
For example, there are different constraints on the use of
pronouns and reduced definite-noun phrases within a
segment than across segment boundaries. While
discourse segmentation is obviously not the only factor
governing the use of referring expressions, it is an impor-
tant one.
2.2 INTENTIONAL STRUCTUR E
A rather straightforward property of discourses, namely,
that they (or, more accurately, those who participate in
them) have an overall purpose, turns out to play a funda-
mental role in the theory of discourse structure. In
particular, some of the purposes that underlie discourses,
and their component segments, provide the means of
individuating discourses and of distinguishing discourses
that are cohere nt from those that are not. These
purposes also make it possible to determine when a
sequence of utterances comprises more than one
discourse.
Although typically the participants in a discourse may
have more than one aim in participating in the discourse
(e.g., a story may entertain its listeners as well as
describe an event; an argument may establish a person's
brilliance as well as convince someone that a claim or
allegation is true), we distinguish one of these purp
as foundational to the discourse. We will refer to it as
d i s c o u r s e p u r p o s e (DP). From an intuitive perspective
discourse purpose is the intention that underlies enga
in the particular discourse. This intention provides
the reason a discourse (a linguistic act), rather than s
other action, is being performed and the reason
particular content of this discourse is being conv
rather than some other information. For each of
discourse segments, we can also single out one inten
- t h e d i sc o u r s e s e g m e n t p u r po s e
(DSP). Fr om an intu
standpoint, the DSP specifies how this segment con
utes to achieving the overall discourse purpose.
assumption that there are single such intentions wi
the end prove too strong. However, this assump
allows us to describe the basic theory more clearly.
must leave to future research (and a subsequent pa
the exploration and discussion of the complications
result from relaxing this assumption.
Typically, an ICP will have a num ber of differ ent k
of intentions that lead to initiating a discourse. One
might include intentions to speak in a certain languag
to utter certain words. Anot her might include intent
to amuse or to impress. The kinds of intentions that
serve as discourse purposes or discourse segm
purposes are distinguished from other intentions by
fact that they are intended to be recognized (cf. A
and Perrault 1980, Sidner 1985), whereas o
intentions are private; that is, the recognition of the
or DSP is
essent ial
to its achieving its intended ef
Discourse purposes and discourse segment purp
share this property with certain utterance-level intent
that Grice (1969) uses in defining utterance mea
(see Section 7).
It is important to distinguish intentions that
intended to be recognized from other kinds of intent
that are associated with discourse. Intentio ns that
intended to be recognized achieve their intended e
only if the intention is recognized. For exampl
compliment achieves its intended effect only if the in
tion to compliment is recognized; in contrast, a scream
boo
typically achieves its intended effect (scaring
hearer) without the hearer having to recognize the sp
er's intention.
Some intention that is private and not intended to
recognized may be the primary motivation for an IC
begin a discourse. For example, the ICP may inten
impress someone or may plan to teach someone.
neither case is the ICP's intention necessarily intende
be recognized. Quite the opposite may be true in
case of impressing, as the ICP may not want the OC
be aware of his intention. When teaching, the ICP
not care whether the OCP knows the ICP is teaching
or her. Thus, the intention that motivates the IC
engage in a discourse may be private. By contrast,
discourse segment purpose is always intended to
recognized.
178 C o m p u t a t i o n a l L i n g u i s t i c s , V o l u m e 12 , N u m b e r 3 , J u l y - S e p t e m b e r
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B a r b a r a J . G r o s z a n d C a n d a c e L . S i d n e r A t t e n t i o n , I n t e n t i o n s , a n d t h e S t r u c t u r e o f D i s c o u r s e
DPs and DSPs are basically the same sorts of
intentions. If an intention is a DP, then its satisfaction is a
main purpose of the discourse, whereas if it is a DSP,
then its satisfaction contributes to the satisfaction of the
DP. The following are some of the types of intentions
that could serve as DP/DSPs, followed by one example of
each type.
1. Intend that some agent intend to perfor m some phys-
ical task. Examp le: I n t e n d t h a t R u t h i n t e n d to f i x t h e
f l a t t ir e .
2. Intend that some agent believe some fact. Example:
I n t e n d t h a t R u t h b e l ie v e t h e c a m p f i r e h a s s t ar t e d.
3. Intend that some agent believe that one fact supports
another. Example:
l n t e n d t h a t R u t h b e l i e v e t h e s m e l l
o f s m o k e p r o v i d e s e v i d e n c e t h a t t h e c a m p f i r e i s s t a rt e d .
4. Intend that some agent intend to identify an object
(existing physical object, imaginary object, plan,
event, event sequence). Example: I n t e n d t h a t R u t h
in t en d t o i d en t i f y m y b i c yc l e .
5. Intend that some agent know some property of an
object. Example:
I n t e n d t h a t R u t h k n o w t h a t m y b ic y -
c l e h a s a f l a t t ir e .
We have identified two structural relations that play
an important role in discourse structure: dominance and
s a t i s f a c t i o n - p r e c e d e n c e . An action that satisfies one
intention, say DSP1, may be intended to provide part of
the satisfact ion of anothe r, say DSP2. Whe n this is the
case, we will say that DSP1 c o n t r i b u t e s t o DSP2;
conversely, we will say that DSP2 d o m i n a t e s DSP1 ( o r
DSP2 D O M DSP1). The dominance relation invokes a
partial ordering on DSPs that we will refer to as the domi-
nance h ie r a r c h y . For some discourses, including task-or-
iented ones, the order in which the DSPs are satisfied
may be significant, as well as being intended to be recog-
nized. We will say that DSP1 satisfaction- precedes DSP2
(or, DSP1
S P
DSP2) whenever DSP1 must be satisfied
bef ore DSP2. 4
Any of the intentions on the preceding list could be
either a DP or a DSP. Furt her more , a given instance o f
any one of them could contribute to another, or to a
different, instance of the same type. For example, the
intention that someone intend to identify some object
might dominate several intentions that she or he know
some property of that object; likewise, the intention to
get someone to believe some fact might dominate a
number of contributing intentions that that person
believe other facts.
As the above list makes clear, the range of intentions
that can serve as discourse, or discourse segment,
purposes is open- ended (cf. Wittgenstein 1953: para-
graph 23), much like the range of intentions that underlie
more general purposeful action. There is no finite list of
discourse purposes, as there is, say, of syntactic catego-
ries. It remains an unresolved research question whether
there is a finite description of the open-ended set of such
intentions. However, even if there were finite
descriptions, there would still be no finite list of
intentions from which to choose. Thus, a theor y of
discourse structure cannot depend on choosing the
DP/DSPs from a fixed list (cf. Reichman-Adar 1984,
Schank et al. 1982, Mann and Thompson 1983), nor on
the particulars of individual intentions. Althoug h the
particulars of individual intentions, like a wide range of
common sense knowledge, are crucial to understanding
any discourse, such particulars cannot serve as the basis
for
d e t e r m i n i n g
discourse structure.
What is essential for discourse structure is that such
intentions bear certain kinds of structural relationships to
one another. Since the CPs can never know the whole
set of intentions that,might serve as DP/DSPs, what they
must recognize is the relevant structural relationships
among intentions. Although there is an infinite numbe r
of intentions, there are only a small number of relations
relevant to discourse structure that can hold between
them.
In this paper we distinguish between the
d e t e r m i n a t i o n
of the DSP and the
rec o g n i t i o n
of it. We use the term
d e t e r m i n a t i o n
to refer to a semantic-like notion, namely,
the complete specification of what is int ende d by whom;
we use the term recognition to refer to a processing
notion, namely, the processing that leads a discourse
participant to identify what the intention is. These are
obviously related concepts; the same information that
determines a DSP may be used by an OCP to recognize it.
However, some questions are relevant to only one of
them. For example, the question of when the informa-
tion becomes available is not relevant to determination
but is crucial to recognition. An analogous distinction
has been drawn with respect to sentence structure; the
parse tree (determination) is differentiated from the pars-
ing process (recognition) that produces the tree.
2 .3 A T T E N T I O N A L S T A T E
The third component of discourse structure, the atten-
tional state, is an abstraction of the participants' focus of
attention as their discourse unfolds. The attentional state
is a property of the discourse itself, not of the discourse
participants. It is inherently dynamic, recording the
objects, properties, and relations that are salient at each
point in the discourse. The attentional state is modeled
by a set of f o c u s s p a c e s ; changes in attentional state are
modeled by a set of transition rules that specify the
conditions for adding and deleting spaces. We call the
collection of focus spaces available at any one time the
f o c u s i n g s t r u c t u r e and the process of manipulating spaces
f o c u s i n g .
The focusing process associates a focus space with
each discourse segment; this space contains those entities
that are salient - either because they have been
mentioned explicitly in the segment or because they
became salient in the process of producing or compre-
hending the utterances in the segmfnt (as in the original
work on focusing: Gros z 1978a). The focus space also
includes the DSP; the inclusion of the purpose reflects the
C o m p u t a t i o n a l
Ling u is ti cs , V o lu me 1 2 , N u mb er 3 , J u ly - S ep tem b er 1 98 6 1 7 9
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Bar bar a
J . G r o s z
a n d C a n d a e e L . S i d n e r A t t e n t i o n , I n t e n t i o n s , a n d t h e S t r u c t u r e o f D i s c o u r s
f a c t t h a t t h e C P s a r e f o c u s e d n o t o n l y o n w h a t t h e y a r e
t a l k in g a b o u t , b u t a l s o o n w h y t h e y a r e t a l k in g a b o u t i t.
T o u n d e r s t a n d t h e a t t e n t i on a l s t a t e c o m p o n e n t o f
d i s c o u r s e s t r u c t u r e , i t i s i m p o r t a n t n o t t o c o n f u s e i t w i t h
t w o o t h e r c o n c e p t s . F i r s t, t h e a t te n t i o n a l s t a t e c o m p o -
n e n t i s n o t e q u i v a l e n t t o c o g n i t i v e s t a t e , b u t i s o n l y o n e
o f i t s c o m p o n e n t s . C o g n i t i v e s t a t e i s a r i c h e r s t r u c t u r e ,
o n e t h a t i n c l u d e s a t l e a s t t h e k n o w l e d g e , b e l i e f s , d e s i r e s ,
a n d i n t e n t i o n s o f a n a g e n t , a s w e l l a s th e c o g n i t i v e c o r r e - '
l a t e s o f t h e a t t e n t i o n a l s t a t e a s m o d e l e d i n t h i s p a p e r .
S e c o n d , a l t h o u g h e a c h f o c u s s p a c e c o n t a i n s a D S P , t h e
f o c u s s t r u c t u r e d o e s not i n c l u d e t h e i n t e n t i o n a l s t r u c t u r e
a s a w h o l e .
F i g u r e 1 i l l u s t r a t e s h o w t h e f o c u s i n g s t r u c t u r e , i n a d d i -
t i o n t o m o d e l i n g a t t e n t i o n a l s t a t e , s e r v e s d u ri n g p r o c e s s -
i n g t o c o o r d i n a t e t h e l i n g u i s t i c a n d i n t e n t i o n a l s t r u c t u r e s .
T h e d i s c o u r s e s e g m e n t s ( t o t h e l e f t o f t h e f i g u r e ) a r e t i e d
t o f o c u s s p a c e s ( d r a w n v e r t i c a ll y d o w n t h e m i d d l e o f t h e
f i g u re ) . T h e f o c u s i n g s t r u c t u r e i s a s t a c k . I n f o r m a t i o n i n
l o w e r s p a c e s i s us u a l ly a c c e s s i b l e f r o m h i g h e r o n e s ( b u t
l e s s s o t h a n t h e i n f o r m a t i o n i n t h e h i g h e r s p a c e s ) ; w e u s e
a l i n e w i t h i n t e r s e c t i n g h a s h m a r k s t o d e n o t e w h e n t h i s i s
n o t t h e c a se . S u b s c r i p t e d t e r m s a r e u s e d t o i n d i c a t e t he
r e l e v a n t c o n t e n t s o f t h e f o c u s s p a c e s b e c a u s e t h e s p a c e s
c o n t a i n r e p r e s e n t a t i o n s o f e n t i t i e s ( i .e . , o b j e c t s , p r o p e r -
t i e s , a n d r e l a t i o n s ) a n d n o t l i n g u i s t i c e x p r e s s i o n s .
P a r t o n e o f F i g u r e 1 s h o w s t h e s t a t e o f f o c u s i n g w h e n
d i s c o u r s e s e g m e n t D S 2 i s b e i n g p r o c e s s e d . S e g m e n t D S1
g a v e r i s e t o F S 1 a n d h a d a s i t s d i s c o u r s e p u r p o s e D S P I .
T h e p r o p e r t i e s , o b j e c t s , r e l a t i o n s , a n d p u r p o s e r e p r e s -
e n t e d i n F S 1 a r e a c c e s s i b l e b u t l e s s s a l i e n t t h a n t h o s e i n
F S 2 . D S 2 y i e l d s a f o c u s s p a c e t h a t i s s t a c k e d r e l a t i v e t o
F S l b e c a u s e D S P 1 o f D S l d o m i n a t e s D S 2 ' s D SP , D S P2 . As
a r e s u lt o f t h e r e l a t i o n s h ip b e t w e e n F S1 a n d F S 2 , r e d u c e d
n o u n p h r a s e s w i l l b e i n t e r p r e t e d d i f f e r e n t l y i n D S 2 t h a n
i n D S 1. F o r e x a m p l e , i f s o m e r e d b a l l s e x i s t i n t h e w o r l d
o n e o f w h i c h i s r e p r e s e n t e d i n D S 2 a n d a n o t h e r i n F S 1 ,
t h e n the red ball u s e d i n D S 2 w i l l b e u n d e r s t o o d t o m e a n
t h e p a r t i c u l a r r e d b a l l t h a t i s r e p r e s e n t e d i n D S 2 . I f ,
h o w e v e r , t h e r e i s a l s o a g r e e n t r u c k ( i n t h e w o r l d ) a n d i t
i s r e p r e s e n t e d o n l y i n F S 1 ,
the green truck
u t t e r e d i n D S 2
w i ll b e u n d e r s t o o d a s r e f e r r i n g t o t h a t g r e e n t r u c k .
P a r t t w o o f F i g u r e 1 s h o w s t h e s t a t e o f fo c u s i n g w h e n
s e g m e n t D S3 is b e i n g p ro c e s s e d . F S 2 h a s b e e n p o p p e d
f r o m t h e s t a c k a n d F S 3 h a s b e e n p u s h e d o n t o i t b e c a u s e
t h e D S P o f D S 3 , D S P3 , is d o m i n a t e d s o l e l y b y D S P 1, n o t
b y D S P 2. I n t h i s e x a m p l e , t h e i n t e n t i o n a l s t r u c t u r e
i n c lu d e s o n l y d o m i n a n c e r e l a t io n s h i p s , a l th o u g h , i t m a y ,
i n g e n e r a l , a l s o i n c l u d e s a t i s f a c t i o n - p r e c e d e n c e r e l a t i o n -
sh ip s .
T h e s t a c k i n g o f f o c u s s p a c e s r e f l e c t s t h e r e l a t i v e s a l i -
e n c e o f t h e e n t i t i e s i n e a c h s p a c e d u r i n g t h e c o r r e s p o n d -
i n g s e g m e n t ' s p o r t i o n o f t h e d i s c o u r se . T h e s t a c k
r e l a t i o n s h i p s a r i s e f r o m t h e w a y s i n w h i c h t h e v a r i o u s
D S P s r e l a t e ; i n f o r m a t i o n a b o u t s u c h r e l a t i o n s h i p s i s
r e p r e s e n t e d i n t h e d o m i n a n c e h i e r a r c h y ( d e p i c t e d o n t h e
r i g h t i n t h e f i g ur e ) . T h e s p a c e s in F i g u r e 1 a r e s n a p s h o t s
i l lu s t r at i n g t h e r e s u l t s o f a s e q u e n c e o f o p e r a t i o n s , s u c h
a s p u s h e s o n t o a n d p o p s f r o m a s t a c k . A p u s h o c c u r s
w h e n t h e D S P f o r a n e w s e g m e n t c o n t r i b u t e s t o t h e D SP
f o r t h e im m e d i a t e l y p r e c e d i n g se g m e n t . W h e n t h e D S P
c o n t r i b u t e s t o s o m e i n t e n t i o n h i g h e r i n t h e d o m i n a n c e
h i e r a r c h y , s e v e r a l f o c u s s p a c e s a r e p o p p e d f r o m t h e s t a c k
b e f o r e t h e n e w o n e i s i n s e r te d .
T w o e s s e n t i a l p r o p e r t i e s o f t h e f o c u s i n g s t r u c t u r e a r e
n o w c l e a r . F i r s t, t h e f o c u s i n g s t r u c t u r e is p a r a s i t i c u p o n
t h e i n t e n t i o n a l s t r u c t u r e , i n t h e s e n s e t h a t t h e r e l a t i o n -
s h ip s a m o n g D S P s d e t e r m i n e p u s h e s a n d po p s . N o t e
h o w e v e r , t h a t t h e r e l e v a n t o p e r a t i o n m a y s o m e t i m e s b e
i n d i c a t e d i n t h e l a n g u a g e it s e lf . F o r e x a m p l e , t h e c u e
w o r d first o f t e n i n d i c a t e s t h e s t a r t o f a s e g m e n t w h o s e
D S P c o n t r i b u t e s t o t h e D S P o f t h e p r e c e d i n g s e g m e n t .
S e c o n d , t h e f o c u s i n g s t r u c t u r e , l i k e t h e i n t e n t i o n a l a n d
l i n g u is t i c s t r u c t u r e s , e v o l v e s a s t h e d i s c o u r s e p r o c e e d s
N o n e o f t h e m e x i s t s a pr i o ri . E v e n i n t h o s e r a r e c a s e s i n
w h i c h a n I C P h a s a c o m p l e t e p l a n f o r t h e d i s c o u r s e p r i o
t o u t t e r i n g a s i n g l e w o r d , t h e i n t e n t i o n a l s t r u c t u r e i
c o n s t r u c t e d b y th e C P s a s t h e d i s c o u r s e p r o g r e s s e s . T h i s
d i s c o u r s e - t i m e c o n s t r u c t i o n o f t h e i n t e n t i o n a l s t r u c t u r e
m a y b e m o r e o b v i o u s l y tr u e f o r s p e a k e r s a n d h e a r e r s o
s p o k e n d i s c o u r s e t h a n f o r r e a d e r s a n d w r i t e r s o f t e x ts
b u t , e v e n f o r t h e w r i t e r , t h e i n t e n t i o n a l s t r u c t u r e i s d e v e l
o p e d a s t h e t e x t i s b e i n g w r i t t e n .
F i g u r e 1 i l l us t r a te s s o m e f u n d a m e n t a l d i s t i nc t i o n s
b e t w e e n t h e i n t e n t i o n a l a n d a t t e n t i o n a l c o m p o n e n t s o
d i s c o u r s e s t r u c t u r e . F i r s t , t h e d o m i n a n c e h i e r a r c h y
p r o v i d e s , a m o n g o t h e r t h i n g s, a c o m p l e t e r e c o r d o f t h e
d i s c o u r s e - l e v e l i n t e n t i o n s a n d t h e i r d o m i n a n c e ( a s w e l
a s , w h e n r e l e v a n t , s a t i s f a c t i o n - p r e c e d e n c e ) r e l a t i o n s h i p s ,
w h e r e a s t h e f o c u s i n g s t r u c t u r e a t a n y o n e t i m e c a n e s s e n -
t i a l l y c o n t a i n o n l y i n f o r m a t i o n t h a t i s r e l e v a n t t o
p u r p o s e s i n a p o r t i o n o f t h e d o m i n a n c e h i e r a r c h y .
S e c o n d , a t t h e c o n c l u s i o n o f a d i s c o u r s e , i f i t c o m p l e t e s
n o r m a l l y , t h e f o c u s s t a c k w i l l b e e m p t y , w h i l e t h e i n t e n -
t i o n a l s t r u c t u r e w i l l h a v e b e e n f u l ly c o n s t r u c t e d . T h i r d
w h e n t h e d i s c o u r s e i s b e i n g p r o c e s s e d , o n l y t h e a t t e n -
t i o n a l s ta t e c a n c o n s t r a i n t h e i n t e r p r e t a t i o n o f r e f e r r i n g
e x p r e s s i o n s d i r e c t l y .
W e c a n n o w a l s o c l a r i f y s o m e m i s i n t e r p r e t a t i o n s o f
f o c u s - s p a c e d i a g r a m s a n d t a s k s t r u c t u r e i n o u r e a r l i e r
w o r k ( G r o s z 1 9 7 8 a , 1 9 8 1 , 1 9 7 4 ) . T h e f o c u s - s p a c e h i e r -
a r c h i e s in t h a t w o r k a r e b e s t s e e n a s r e p r e s e n t i n g a t t e n -
t i o n a l s t a t e . T h e t a s k s t r u c t u r e w a s u s e d i n t w o w a y s :
1. t o r e p r e s e n t c o m m o n k n o w l e d g e a b o u t t h e t a s k ;
2 . a s a s p e c i a l c a s e o f t h e i n t e n t io n a l s t r u c t u r e w e p o s i
i n t h i s p a p e r .
A l t h o u g h t h e s a m e r e p r e s e n t a t i o n a l s c h e m e w a s u s e d f o r
e n c o d i n g t h e f o c u s - s p a c e h i e r a r c h i e s a n d t h e t a s k s t r u c -
t u r e ( p a r t i t i o n e d n e t w o r k s : H e n d r i x 1 9 7 9 ) , t h e t w o
s t r u c t u r e s w e r e d i s ti n c t.
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F i g u re 1 . D i s c o u r s e S e g m e n t s , F o c u s S p a c e s a n d D o m i n a n c e H i e r a rc h y .
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B a r b a r a J. Grosz a n d C a n d a c e L . S i d n e r A t t e n t i o n , I n t e n t i o n s , a n d t h e S t r u c t u r e o f D i s c o u r s e
S e v e r a l r e s e a r c h e r s ( e .g . , L i n d e a n d G o g u e n 1 9 7 8 ,
R e i c h m a n - A d a r 1 9 8 4 ) m i s i n t e r p r e t e d t h e o r i g i n a l
r e s e a r c h i n a n u n f o r t u n a t e a n d u n i n t e n d e d w a y : t h e y
t o o k t h e f o c u s - s p a c e h i e r a r c h y t o i n c l u d e ( o r b e i d e n t i c a l
t o ) t h e t a s k st r u c tu r e . T h e c o n f l a t i o n o f th e s e t w o s t r u c -
t u r e s f o r c e s a s in g le s t r u c t u r e t o c o n t a i n i n f o r m a t i o n
a b o u t a t t e n t i o n a l s t a t e , i n t e n t i o n a l r e l a t io n s h i p s , a n d
g e n e r a l t a sk , k n o w l e d g e . I t p r e v e n t s a t h e o r y f r o m
a c c o u n t i n g a d e q u a t e l y f o r c e r t a i n a s p e c t s o f d i s c o u r s e ,
i n c l u d i n g i n t e r r u p t i o n s ( s e e S e c t i o n 5 ) .
A s e c o n d i n s t a n c e o f c o n f u s i o n w a s t o i n f e r ( i n c o r -
r e c t l y ) t h a t t h e t a s k s t r u c t u r e w a s n e c e s s a r i l y a p r e b u i l t
t r e e . I f t h e t a s k s t r u c t u r e i s t a k e n t o b e a s p e c i a l c a s e o f
i n t e n t i o n a l s t r u c t u re , i t b e c o m e s c l e a r t h a t t h e t r e e s t r u c -
t u r e i s s i m p l y a m o r e c o n s t r a i n e d s t r u c t u r e t h a n o n e
m i g h t r e q u i re f o r o t h e r d i s c o u r se s ; t h e n a t u r e o f t h e t a s k
r e l a t e d t o t h e t a s k - o r i e n t e d d i s c o u r s e i s s u c h t h a t t h e
d o m i n a n c e h ie r ~ ir c hy o f t h e i n t e n t i o n a l s t r u c t u r e o f t h e
d i a lo g u e h a s b o t h d o m i n a n c e a n d s a t i s f a c t i o n - p re c e d e n c e
r e l a t io n s h i p s , 5 w h i l e o t h e r d i s c o u r s e s m a y n o t e x h i b i t
s i g n i f i c a n t p r e c e d e n c e c o n s t r a i n t s a m o n g t h e D S P s .
F u r t h e r m o r e , t h e r e h a s n e v e r b e e n a n y r e a s o n t o a s s u m e
t h a t t h e t a s k s t r u c t u r e s i n t a s k - o r i e n t e d d i a l o g u e s a r e
p r e b u i lt , a n y m o r e t h a n t h e i n t e n t i o n a l s t r u c t u r e o f a n y
o t h e r k i n d o f d i s c o u r s e s. I t i s r a t h e r t h a t o n e o b j e c t i v e o f
d i s c o u r s e t h e o r y ( n o t a t o p i c c o n s i d e r e d h e r e , h o w e v e r )
i s t o e x p l a i n h o w t h e O C P b u i l d s u p a m o d e l o f t h e t a s k
s t r u c t u r e b y u s i n g i n f o r m a t i o n s u p p l i e d i n t h e d i s c o u r s e .
H o w e v e r , i t i s i m p o r t a n t t o n o t e t h a t c o n f l a t i n g t h e
a f o r e m e n t i o n e d t w o r o l e s o f i n f o r m a t i o n a b o u t t h e t a s k
i t s e l f ( a s a p o r t i o n o f g e n e r a l c o m m o n s e n s e k n o w l e d g e
a n d a s a s p e c i a l c a s e o f i n t e n t i o n a l s t r u c t u r e ) w a s r e g r e t -
t a b l e , a s i t f a i l s t o m a k e a n i m p o r t a n t d i s t i n c t i o n .
F u r t h e r m o r e , a s i s c l e a r w h e n i n t e n t i o n a l s t r u c t u r e s a r e
c o n s i d e r e d m o r e g e n e r a ll y , s u c h a c o n f l a t i o n o f r o l e s
d o e s n o t a l lo w f o r d if f e r e n ce s b e t w e e n w h a t o n e k n o w s
a b o u t a t a s k a n d o n e ' s i n t e n t i o n s f o r ( o r w h a t o n e m a k e s
e x p l ic i t in d i s c o u r s e a b o u t ) p e r f o r m i n g a t a s k .
I n s u m m a r y , t h e f o c u s i n g s t r u c t u r e i s t h e c e n t r a l
r e p o s i t o r y f o r t h e c o n t e x t u a l i n f o r m a t i o n n e e d e d t o p r o c -
e s s u t t e r a n c e s a t e a c h p o i n t i n t h e d i s c o u r s e . I t d i s t i n -
g u i s h e s t h o s e o b j e c t s , p r o p e r t i e s , a n d r e l a t i o n s t h a t a r e
m o s t s a l i e n t a t t h a t p o i n t a n d , m o r e o v e r , h a s l i n k s t o
r e l e v a n t p a r t s o f b o t h t h e l in g u is t ic a n d i n t e n t i o n a l s t r u c -
t u r e s. D u r i n g a d i s c ou r s e , a n in c r e a s i n g a m o u n t o f i n f o r -
m a t i o n , o n l y s o m e o f w h i c h c o n t i n u e s t o b e n e e d e d f o r
t h e i n t e r p r e t a t i o n o f s u b s e q u e n t u t t e r a n c e s , i s d i s c u s se d .
H e n c e , i t b e c o m e s m o r e a n d m o r e n e c e s s a r y t o b e a b l e
t o i d e n t i f y r e l e v a n t d i s c o u r s e s e g m e n t s , t h e e n t i t i e s t h e y
m a k e s a l i e nt , a n d th e i r D S P s. T h e r o l e o f a t t e n t i o n a l
s t a t e i n d e l i n e a t i n g t h e i n f o r m a t i o n n e c e s s a r y f o r u n d e r -
s t a n d i n g i s t h u s c e n t r a l t o d i s c o u r s e p r o c e s s i n g .
3 T w o E X A M PL E S
T o i l l u s t r a t e t h e b a s i c t h e o r y w e h a v e j u s t s k e t c h e d , w e
w i l l g i v e a b r i e f a n a l y s i s o f t w o k i n d s o f d i s c o u r s e : a n
a r g u m e n t f r o m a r h e t o r i c t e x t a n d ~i t a s k - o r i e n t e d
d i a l o g u e . F o r e a c h e x a m p l e w e d i s c u s s t h e s e g m e n t a t i o n
o f t h e d i s c o u r s e , t h e i n t e n t i o n s t h a t u n d e r l i e t h i s s e g m e n -
t a t i o n , a n d t h e r e l a t i o n s h i p s a m o n g t h e v a r i o u s D S P s . I n
e a c h c a s e , w e p o i n t o u t s o m e o f t h e l i n g u i s t i c d e v i c e s
u s e d t o i n d i c a t e s e g m e n t b o u n d a r i e s a s w e l l a s s o m e o f
t h e e x p r e s s i o n s w h o s e i n t e r p r e t a t i o n s d e p e n d o n t h o s e
b o u n d a r i e s . T h e a n a l y s i s is c o n c e r n e d w i t h s p e c i f y i n g
c e r t a i n a s p e c t s o f t h e b e h a v i o r t o b e e x p l i c a t e d b y a
t h e o r y o f d i sc o u r s e ; t h e r e m a i n d e r o f t h e p a p e r p r o v i d e s
a p a r t i a l a c c o u n t o f t h is b e h a v i o r .
3.1 AN ARGUME NT
O u r f i r s t e x a m p l e i s a n a r g u m e n t t a k e n f r o m a r h e t o r i c
t d x t ( H o l m e s a n d G a l l a g h e r 1 9 1 76 ) . I t i s a n e x a m p l e u s e d
b y C o h e n ( 1 9 8 3 ) i n h e r w o r k o n t h e s t r u c t u r e o f a r g u -
m e n t s . F i g u r e 2 s h o w s t h e d i a l o g u e a n d t h e e i g h t
d i s c o u r s e s e g m e n t s o f w h i c h i t i s c o m p o s e d . T h e d i v i s i o n
o f t h e a r g u m e n t i n to s e p a r a t e ( n u m b e r e d ) c l a u s e s i s
C o h e n ' s , b u t o u r a n a l y s i s o f t h e d i s c o u r s e s t r u c t u r e i s
d i f f e r e n t , s in c e i n C o h e n ' s a n a l y s i s , e v e r y u t t e r a n c e i s
d i r e c t l y s u b o r d i n a t e d t o a n o t h e r u t t e r a n c e , a n d t h e r e i s
o n l y o n e s t r u c t u r e t o e n c o d e l i n g u i s t i c s e g m e n t a t i o n a n d
t h e p u r p o s e s o f u t t e r a n c e s . A l t h o u g h b o t h a n a l y s e s
s e g m e n t u t t e r a n c e ( 4 ) s e p a r a t e l y f r o m u t t e r a n c e s ( 1 - 3 ) ,
s o m e r e a d e r s p l a c e t h i s u t t e r a n c e i n D S1 w i t h u t t e r a n c e s
( 1 ) t h r o u g h ( 3 ) ; t h i s is a n e x a m p l e o f t h e k i n d o f d i s a -
g r e e m e n t a b o u t b o u n d a r y u t t e r a n c e s f o u n d i n M a n n ' s
d a t a ( a s d i s c u s s e d i n S e c t i o n 2 . 1 ). T h e t w o p l a c e m e n t s
l e a d t o s l i g h t l y d i f f e r e n t D S P s , b u t n o t t o r a d i c a l l y d i f f e r -
e n t i n t e n ti o n a l s t r uc t u r e s . B e c a u s e t h e d i ff e r e n c e s d o n o t
a f f e c t t h e m a j o r t h r u s t o f t h e a r g u m e n t , w e w i l l d i s c u s s
o n l y o n e s e g m e n t a t i o n .
182
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Barbara J. Grosz and Candace L. S i d n e r A t t e n t i o n , I n t e n t i o n s , a n d t h e S t r u c t u r e o f D i s c o u r s e
DS0
DS2
3
5
D S 6
I
I . _ _ .
DS7
1. The mov ie s a re so a t t ra c t i ve t o t he g rea t Amer i ca n pub l i c ,
2. e spec i a l l y t o young peop le ,
3. t ha t i t i s t ime to t ake ca re f u l t hough t abou t t he i r e f fec t on mind
and mora l s .
4 . Ough t any pa re n t t o pe rmi t h i s ch i l d ren t o a t t end a mov ing p i c tu re
show o f t en o r w i thou t be ing qu i t e ce r t a in o f t he show he pe rmi t s
them to see?
5. No one can deny , o f cou r se , t ha t g rea t educa t iona l and e th i ca l
ga in s may be made t h rough the mov ies
6. becau se o f t he i r a s ton i s h ing v iv idness .
7. Bu t t he impor t an t fac t t o be de t e r mined i s t he t o t a l r e su l t o f
con t in uous and i nd i s c r im ina t e a t t en dance on shows o f t h i s k ind.
8. Can i t be o the r t han ha rm fu l?
9. In t he f i r s t p l ace t h e cha r ac t e r o f t he p l ays is se ldom o f t he
best .
10. One has on ly t o read t he eve r -p r esen t mov ie b i l l b oa rd t o see how
c h e a p , m e l o d r a m a t i c a n d v u l g a r m os t of t h e p h o t o p l a y s a r e .
11 . Even the bes t p l ays , moreove r , a re bound to be exc i t i ng and
o v e r - e m o t i o n a l .
12 . Wi thout spoke n words , fac i a l exp r ess io n and ges tu re mus t ca r r y t he
mean ing :
13. bu t on ly s t ro ng emot ion , o r bu f fo one ry can be rep r esen t ed t h rou gh
f a c i al e x p r e s s i o n a n d g e s t u r e .
14. The more reas onab l e and qu i e t a sp ec t s o f l ife a re ne cessa r i l y
n e g l e c t e d .
15. How can ou r y oung peop le d r ink i n t h rou gh the i r eyes a con t inu ous
s p e c t a c l e o f i n t e n s e a n d s t r a i n e d a c t i v i t y a n d f e el i n g w i t h o u t
h a r m f u l e f f e c t s ?
16. P a ren t s and t each e rs w il l do wel l t o gua rd t he you ng aga ins t
o v e r i n d u l g e n c e i n t h e t a s t e f o r t h e m o v i e .
Figure 2. The Movies Essay.
C o m p u t a t i o n a l
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B a r b a r a J. Grosz a n d C a n d a c e L . S i d n e r A t t e n t i o n , I n t e n t io n s , a n d t h e S t r u c t u r e o f D i s c o u r s e
F i g u r e 3 l is t s t h e p r i m a r y c o m p o n e n t o f t h e D S P f o r
e a c h o f t h e s e s e g m e n t s a n d F i g u r e 4 s h o w s t h e d o m i -
n a n c e r e l a t i o n s h ip s t h a t h ol d a m o n g t h e s e i nt e n t i o n s. I n
S e c t i o n 7 w e d i s c u s s a d d i t i o n a l c o m p o n e n t s o f t h e
d i s c o u r s e s e g m e n t p u r p o s e ; b e c a u s e t h e s e a d d i t i o n a l
c o m p o n e n t s a r e m o r e i m p o r t a n t f o r c o m p l e t e n e s s o f t he
t h e o r y t h a n f o r d e t e r m i n i n g t h e e s se n t i a l d o m i n a n c e a n d
s a t i s f a c t i o n - p r e c e d e n c e r e l a t i o n s h i p s b e t w e e n D S P s , w e
o m i t su c h d e ta i l s h e r e . R a t h e r t h a n c o m m i t o u r s e l v e s t o
a f o r m a l l a n g u a g e i n w h i c h t o e x p r e s s t h e i n t e n t i o n s o f
t h e d i s c o u r s e , w e w il l u s e a s h o r t h a n d n o t a t i o n a n d
E n g l i s h s e n t e n c e s t h a t a r e i n t e n d e d t o b e a g l o s s f o r a
f o r m a l s t a t e m e n t o f t h e a c t u a l i n t e n ti o n s .
I O : ( I n t e n d
I 1 : ( I n t e n d
I 2 : ( I n t e n d
1 3 : ( I n t e n d
1 4 : ( I n t e n d
1 5 : ( I n t e n d
I 6 : ( I n t e n d
1 7 : ( I n t e n d
I C P ( B el ie v e O C P P O ) )
w h e r e P O = t h e p r o p o s i t i o n t h a t p a r e n t s a n d t e a c h e r s s h o u l d g u a r d t h e y o u n g
f r o m o v e r i n d u l g e n c e i n th e m o v i e s .
I C P ( B e l i e ve O C P P 1 ) )
w h e r e P 1 = t h e p r o p o s i t i o n t h a t i t i s t i m e t o c o n s i d e r t h e e f f e c t o f m o v i e s o n
m i n d a n d m o r a l s .
I C P ( B e li e ve O C P P 2 ) )
w h e r e P 2 = t h e p r o p o s i t i o n t h a t y o u n g p e o p l e c a n n o t d r i n k i n t h r o u g h t h e i r e y e s
a c o n t i n u o u s s p e c t a c l e o f i n te n s e a n d s t r a i n e d a c t i v i t y w i t h o u t h a r m f u l e f f e c t s .
I C P ( B e li e ve O C P P 3 ) )
w h e r e P 3 - - t h e p r o p o s i t i o n t h a t i t i s u n d e n i a b l e t h a t g r e a t e d u c a t i o n a l a n d
e t h i c a l g a i n s m a y b e m a d e t h r o u g h t h e m o v i e s .
I C P ( B e l ie v e O C P P 4 ) )
w h e r e P 4 = t h e p r o p o s i t i o n t h a t a l t h o u g h t h e r e a r e g a i n s , t h e t o t a l r e s u l t o f
c o n t i n u o u s a n d i n d i s c r i m i n a t e a t t e n d a n c e a t m o v i e s is h a r m f u l .
I C P ( B e l ie v e O C P P 5 ) )
w h e r e P 5 = t h e p r o p o s i t i o n t h a t t h e c o n t e n t o f m o v i e s ( i. e ., t h e c h a r a c t e r o f t h e
p l a y s ) i s n o t t h e b e s t .
I C P ( B e l ie v e O C P P 6 ) )
w h e r e P 6 = t h e p r o p o s i t i o n t h a t t h e s t o ri e s ( i. e ., th e p l a y s ) i n m o v i e s a r e e x c i t -
i n g a n d o v e r - e m o t i o n a l .
I C P ( B e l ie v e O C P P 7 ) )
w h e r e P 7 = t h e p r o p o s it i o n th a t m o v i e s p o r t r a y s t r o n g e m o t i o n a n d b u f f o o n e r y
w h i l e n e g l e c t in g t h e q u i e t a n d r e a s o n a b l e a s p e c t s o f l i fe .
F i g u re 3. P r i m a r y i n te n t i o n s o f t h e D S P s f o r M o v i e s e s s a y .
I 0 D O M I 1
I 0 D O M 12
1 2 D O M 1 3
1 2 D O M 1 4
1 4 D O M 1 5
1 4 D O M 1 6
1 6 D O M 1 7
F i g u re 4 . D o m i n a n c e r e l a t i o n s h i p s f o r t h e D S P s o f t h e M o v i e s e s s a y .
184
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~ f
B a r b a r a
J. Grosz
a n d C a n d a e e L . S i d n e r A t t e n t i o n , I n t e n t i o n s , a n d t h e S t r u c t u r e o f D i s c o u r s e
All the primary intentions for this essay are intentions
that the reader (OCP) come to believe some proposition.
Some of these propositions, such as P5 and P6, can be
read off the surface utterances directly. Other prop-
ositions and the intemions of which they are part, such as
P2 and 12, are moCe indirect. Like the Gric ean utter -
ance'-level intentions (the analogy with these will be
explored in Section 7), DSPs may or may not be directly
expressed in the discourse. In particular, they may be
expressed in any of the following ways:
1 . e x p l i c i t l y
as in
I i n t e n d f o r y o u t o b e l ie v e t h a t i t 's t i m e
t o c o n s i d e r t h e e f f e c t s o f m o v i e s o n m i n d a n d m o r a l s .
[which would pr oduce I1 ]
2 . d i r e c t ly , i n o n e u t t e r a n c e ,
as in (3) [which does
prod uce I 1 ]
3 . d i r e c t l y , t h r o u g h m u l t i p l e u t t e r a n c e s ,
as in using (7)
and the utterance
I t c a n o n l y b e h a r m f u l
to produce
14,
4 . b y d e r i v a t i o n , i n o n e o r m o r e u t t e r a n c e s w i t h a n a s s o c i -
a t e d c o n t e x t ,
as in (15) to produce 12.
Not only may information about the DSP be conveyed
by a number of features of the utterances in a discourse,
but it also may come in any utterance in a segment. For
example, although I0 is the DP, it is stated directly only in
the last utterance of the essay. This leads to a number of
questions about the ways in which OCPs can recognize
discourse purposes, and about those junctures at which
they need to do so. We turn to these matters directly in
Subsection 4.1.
This discourse also provides several examples of the
different kinds of interactions that can hold between the
linguistic expressions in a discourse and the discourse
structure. It includes examples of the devices that may be
used to mark overtly the boundaries between discourse
segments - examples of the use of aspect, mood, and
particular cue phras es - as well as of the use of referrin g
expressions that are affected by discourse segment boun-
daries.
The use of cue phrases to indicate discourse bounda-
ries is illustrated in utterances (9) and (11); in (9) the
phrase
i n t h e f i r s t p l a c e
marks the beginning of DS5 while
in (11)
m o r e o v e r
ends DS5 and marks the start of DS6.
These phrases also carry information about the inten-
tional structure, namely, that DSP5 and DSP6 are domi-
nated b y DSP4. In some cases, cue phrases have multiple
functions; they convey propositional content as well as
marking discourse segment boundaries.. The
b u t
in utter-
ance (7) is an example of such a multiple function use.
The boundaries between DS1 and DS2, DS4 and DS5,
and DS4 and DS2 reflect changes of aspect and mood.
The switch from declarative, present tense to interroga-
tive modal aspect does not in itself seem to signal the
boundary (for recognition purposes) in this discourse
unambiguously, but it does indicate a possible line of
demarcation which, in fact, is valid.
The effect of segmentation on referring expressions is
shown by the use of the generic noun phrase
a m o v i n g
p i c t u r e s h o w
in (4). Althoug h a reference to the movies
was made with a pronoun
( t h e i r )
in (3), a full noun
phrase is used in (4). This use reflects, and perha ps in
part marks, the boundary between the segments DS1 and
DS2.
Finally, this discourse has an example of the trade-off
between explicitly marking a discourse boundary, as well
as the relationship between the associated DSPs, and
reasoning about the intentions themselves. There is no
overt linguistic marker of the beginning of DS7; its sepa-
ration must be inferred from DSP7 and its relationship to
DSP6.
3.2 A TASK-ORIENTED DIALOGUE
The second example is a fragment of a task-oriented
dialogue taken from Grosz (1981; it is from the same
corpus that was used by Grosz 1974). Figure 5 contains
the dialogue fragment and indicates the boundaries for its
main segments. 7 Figure 6 gives the prima ry co mpo nent of
the DSPs for this fragment and shows the dominance
relationships between them.
In contrast with the movies essay, the primary compo-
nents o f the DSPs in this dialogue are mo stly intentions of
the segment's ICP that the OCP intend to perform some
action. Also, unlike the essay, the dialogue has two
agents initiating the different discourse segments. In this
particular segment, the expert is the ICP of DS1 and DS5,
while the appren tice is the ICP of DS2-4. To furnish a
complete account of the intentional structure of this
discourse, one must be able to say how the satisfaction of
one agent's intentions can contribute to satisfying the
intentions of another agent. Such an account is beyo nd
the scope of this paper, but in Section 7 we discffss some
of the complexities involved in providing one (as well as
its role in discourse theory).
For the purposes of discussing this example, though,
we need to postulate two properties of the relationships
among the participants' intentions. These properties
seem to be rooted in features of cooperative behavior
and depend on the two participants' sharing some partic-
ular knowledge of the task. First, it is a share d belief
that, unless he states otherwise, the OCP will adopt the
intention to perform an action that the ICP intended him
to. Second, in adopting the intention to carry out that
action, the OCP also intends to perform whatever
subactions are necessary. Thus, once the apprentice,
intends to remove the flywheel, he also commits himself
to the collateral intentions of loosening the setscrews and
pulling the wheel off. Note, however, that not all the
subactions need to be introduced explicitly into the
discourse. The apprentice may do several actions that are
never mentioned, and the expert may assume that these
are being undertaken on the basis of other information
that the apprentice obtains. The partiality of the inten-
tional structure stems to some extent from these charac-
teristics of intentions and actions.
C o m p u t a t i o n a l L i n g u i s t i c s , V o l u m e
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Barbara J . Grosz and Candace L . S idner At tent ion , In tentions , and the S tructure
of Discourse
DS1 (1)
(2)
(3)
(4)
DS2 (5 )
( S )
(7)
( B )
( 9 )
1 0 )
(11)
DS3
(12)
( 1 3 )
( 1 4 )
15)
16)
(17)
DS4 (18)
(19)
(z0)
( z l )
(zz)
(z3)
(24)
(z5)
E: F i r s t you have t o remov e the f l ywhee l .
A: How do I rem ove the f lywhe el?
E: F i r s t , l oose n t he two a l l en head se t sc rews
hold ing i t to the shaft , then pul l i t o ff .
A: OK.
I can on ly f i nd one sc rew . Where ' s t he o the r one?
E: On the hub of the f lywheel .
A: Tha t ' s t he one I found . Where ' s t he o the r one?
E: Abou t n ine ty deg re es a roun d the hub f rom the f i r s t one .
A: I don ' t unde rs t and . I can only f ind one. Oh
wai t , yes I th i nk I was on the wron g wheel .
E: Show me what you are doing .
A: I was on th e wro ng wheel and l can f ind
them bo th now.
The t oo l I have i s awkward . I s t he re ano the r
too l t ha t I cou ld u se i n s t e ad?
E: Show me the tool you are using .
A: OK.
E: Are you su re you a re u s ing t he r i gh t s i ze
k e y ?
A: I ' l l t ry some oth ers .
I fou nd an angle I can get a t i t.
The two sc rews a re l oose , bu t I 'm hav ing t roub l e
ge t t i ng t he whee l o f f .
E: Use the whe elp ul l er Do you know how to use
i t?
A: No .
E: Do you know what i t looks l ike?
A: Yes.
E: Show it to me please.
A: OK.
E: Good , Loosen t he sc rew in t he cen t e r and
p lace t he j aws a round the hub o f t he
wheel , t hen t i gh t en t he sc rew on to t he
cen t e r o f t he sha f t . The whee l shou ld
slide off.
Figure 5. A segment of a task-oriented dialogue.
As in the movies essay, some of the DSPs for this
dialogue are expressed directly in utterances. Fo r
instance, utterances (1), (5), and (12) directly express
the primary components of DSP1, DSP2 and DSP3,
respectively. The primary compone nt of DSP4 is a
derived intention. The surface intention of
but I m
having trouble getting the wheel off
is tha t the apprentice
intends the expert to believe that the apprentice is having
trouble takin g off the flywheel. 14 is derived fr om the
utterance and its surface intention, as well as from
features of discourse, conventions about what intentions
are associated with the
1 am having trouble doing X
type
186
of utterance, and what the 1CP and OCP know about the
task they have undertaken.
The dominance relationship that holds between I1 and
12, as well as the one that holds between I1 and 13, may
seem problematic at first glance. It is not clear how
locating any single setscrew contributes to removing the
flywheel. It is even less clear how, in and of itself, identi-
fying ano the r tool does. Two facts provide the link: first,
that the apprentice (the OCP of DS1) has taken on the
task of removing the flywheel; second, that the appren-
tice and expert share certain knowledge about the task.
Some of this shared task knowledge comes from the
discourse per se [e.g., utterance (3)], but some of it
Computat ional
Linguistics, Volume
1 2 , N u m b e r 3 , J u l y - S e p te m b e r
1986
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B a r b a r a J . G r o s z a n d C a n d a c e L . S i d n e r A t t e n t i o n , I n t e n t i o n s , a n d t h e S t r u c t u r e o f D i s c o u r s e
c o m e s f r o m g e n e r a l k n o w l e d g e , p e r c e p t u a l i n f o r m a t i o n ,
a n d t h e li k e. T h u s , a c o m b i n a t i o n o f i n f o r m a t i o n i s r e l e -
v a n t t o d e t e r m i n i n g 1 2 a n d 1 3 a n d t h e i r r e l a t i o n s h i p s t o
I 1 , i n c l u d i n g a l l o f t h e f o l l o w i n g : t h e f a c t t h a t I 1 is p a r t
o f t h e i n t e n t i o n a l s t r u c t u r e , t h e f a c t t h a t t h e a p p r e n t i c e i s
c u r r e n t l y w o r k i n g o n s a t i s f y i n g I 1 , t h e u t t e r a n c e - l e v e l
i n t e n t io n s o f u t t e r a n c e s ( 5 ) a n d ( 1 2 ) , a n d g e n e r a l k n o w -
l e d g e a b o u t t h e t a s k .
T h e s a t i s f a c t i o n - p r e c e d e n c e r e l a t i o n s a m o n g 1 2 , 1 3 ,
a n d 1 4 a r e n o t c o m m u n i c a t e d d i r e c t l y i n t h e d i a l o g u e ,
b u t , l i k e d o m i n a n c e r e l a t i o n s , d e p e n d o n d o m a i n k n o w -
l e d ge . O n e p i e c e o f r e l e v a n t k n o w l e d g e i s t h a t a s a t is f a c -
t i o n p r e c e d e n c e r e l a t i o n e x i s t s b e t w e e n l o o s e n i n g t h e
s e t s c r e w s a n d pu l l i n g o f f t h e f l y w h e e l . T h a t r e l a t i o n is
s h a r e d k n o w l e d g e t h a t i s s t a t e d d i r e c t l y
(F ir s t loosen . . . .
t h n p u l l ) .
T h e r e l a t io n , a l o n g w i t h t h e f a c t t h a t b o t h 1 2
a n d 1 3 c o n t r i b u t e t o l o o s e n i n g t h e s e t s c r e w s , a n d t h a t 1 4
c o n t r i b u t e s t o p u l l i n g o f f t h e f l y w h e e l , m a k e s i t p o s s i b l e
t o c o n c l u d e 1 3 S P 1 4 a n d 1 2 S P 14 . T o c o n c l u d e t h a t 1 2
S P 13 , t h e a p p r e n t i c e m u s t e m p l o y k n o w l e d g e o f h o w t o
g o a b o u t l o o s e n i n g s c r e w - l i k e o b j e c t s .
T h e d o m i n a n c e a n d s a t i s f a c t i o n - p r e c e d e n c e r e l a t i o n s
f o r t h i s t a s k - o r i e n t e d f r a g m e n t f o r m a t r e e o f i n t e n t i o n s
r a t h e r t h a n j u s t a p a r t i a l o r d e r i n g . I n g e n e r a l , h o w e v e r ,
f o r a n y f r a g m e n t , t a s k - o r i e n t e d o r o t h e r w i s e , t h i s i s n o t
n e c e s s a r y .
I t i s e s s e n t i a l t o n o t i c e t h a t t h e i n t e n t i o n a l s t r u c t u r e i s
n e i t h e r i d e n t i c a l t o n o r i s o m o r p h i c t o a g e n e r a l p l a n f o r
r e m o v i n g th e f l y w h e e l . I t i s n o t i d e n t ic a l b e c a u s e a p l a n
e n c o m p a s s e s m o r e t h a n a c o l l e c t i o n o f i n t e n t i o n s a n d
r e l a t i o n s h i p s b e t w e e n t h e m ( c o m p a r e P o l l a c k ' s ( 1 9 8 6 )
c r i ti q u e o f A I p l a n n i n g f o r m a l i s m s a s t h e b a s i s f o r i n f e r -
r i n g i n t e n t io n s i n d i s c o u r se ) . I t is n o t i s o m o r p h i c b e c a u s e
t h e i n t e n t i o n a l s t r u c t u r e h a s a d i f f e r e n t s u b s t r u c t u r e f r o m
t h e g e n e r a l p l a n f o r r e m o v i n g t h e f l y w h e e l . I n a d d i t io n
t o t h e i n t e n t i o n s a r i s i n g f r o m s t e p s i n t h e p l a n , t h e i n t e n -
t i o n a l s t r u c t u r e t y p i c a l l y c o n t a i n s D S P s c o r r e s p o n d i n g t o
i n t e n t i o n s g e n e r a t e d b y t h e p a r t i c u l a r e x e c u t i o n o f t h e
t a s k a n d t h e d i a l o gu e . F o r e x a m p l e , th e g e n e r a l p l a n f o r
t h e d i s a s s e m b l y o f a f ly w h e e l i n c l u d e s s u b p l a n s f o r l o o s -
e n i n g t h e s e t s c r e w s a n d p u l l in g o f f t h e w h e e l ; i t m i g h t
a l s o in c l u d e s u b p l a n s ( o f t h e l o o s e n i n g s t e p ) f o r f i n di n g
t h e s e t s c r e w s , f i n d i n g a t o o l w i t h w h i c h t o l o o s e n t h e
s c r e w s , a n d l o o s e n i n g e a c h s c r e w i n d i v i d u a l l y . H o w e v e r ,
t h i s p l a n w o u l d n o t c o n t a i n c o n t i n g e n c y s u b p l a n s f o r
w h a t t o d o w h e n o n e c a n n o t f i n d t h e s c r e w s o r r e a l i z e s
t h a t t h e a v a i l a b l e t o o l i s u n s a t i s f a c t o r y . I n t e n t i o n s I 2 a n d
I 3 s t e m f r o m d i f f i c u l t i e s e n c o u n t e r e d i n l o c a t i n g a n d
l o o s e n i n g t h e s e t s c re w s . T h u s , t h e i n te n t i o n a l s t r u c t u r e
f o r t h is f r a g m e n t i s n o t i s o m o r p h i c t o t h e g e n e r a l p l a n f o r
r e m o v i n g t h e f l y w h e e l .
U t t e r a n c e ( 1 8 ) o f f e r s a n o t h e r e x a m p l e o f t h e d i ff e r -
e n c e b e t w e e n t h e i n t e n t i o n a l s t r u c t u r e a n d a g e n e r a l p l a n
f o r th e t a s k . T h i s u t t e r a n c e i s p a r t o f D S 4 - n o t j u s t p a r t
o f DS 1 - e v e n t h o u g h i t c o n t a i n s r e f e r e n c e s t o m o r e t h a n
o n e s i n g l e p a r t o f t h e o v e r a l l t a s k ( w h i c h i s w h a t I 1 i s
a b o u t ) . I t f u n c t i o n s t o e s t a b l i s h a n e w D S P , 1 4 , a s m o s t
s a l ie n t . R a t h e r t h a n b e i n g r e g a r d e d a s a r e p o r t o n t h e
o v e r a l l s t a t u s o f t h e t a s k , t h e f i r s t c l a u s e i s b e s t s e e n a s
m o d i f y i n g t h e D S P . 8 W i t h i t, t h e a p p r e n t i c e t e l ls t h e
e x p e r t t h a t t h e t r o u b l e i n r e m o v i n g t h e w h e e l i s n o t w i t h
t h e s c r e w s . T h u s , a l t h o u g h g e n e r a l t a s k k n o w l e d g e i s
u s e d i n d e t e r m i n i n g t h e i n t e n t i o n a l s t r u c t u r e , i t i s n o t
id en t i ca l t o i t .
I n t h is d i a l o g u e , t h e r e a r e f e w e r i n s t a n c e s i n w h i c h c u e
p h r a s e s a r e e m p l o y e d t o i n d i c a t e s e g m e n t b o u n d a r i e s
t h a n o c c u r i n t h e m o v i e s e s sa y . T h e p r i m a r y e x a m p l e i s
t h e u s e o f
f i r s t
i n ( 1 ) t o m a r k t h e s t a r t o f th e s e g m e n t
a n d t o i n d i c a t e t h a t i t s D S P i s t h e f i r s t o f s e v e r a l
i n t e n t i o n s w h o s e s a t i s f a c t i o n w i ll c o n t r i b u t e t o s a t i s fy i n g
t h e l a r g e r d i s c o u r se o f w h i c h t h e y a r e a p a r t .
P r i m a r y I n t e n t i o n s :
I I ( I n t e n d
Exper t
( I n t e n d
Appren t ic e
( R e m o v e A f l y w h e e l ) ))
I 2 : ( I n t e n d A ( I n t e n d E (T e l l E A ( L o c a t i o n o t h e r s e t s c r e w ) ) ) )
I 3 : ( I n t e n d A ( I n t e n d E ( I d e n t if y E A a n o t h e r t o o l ) ) )
I 4 : ( I n t e n d A ( I n t e n d E ( T e l l E A ( H o w ( G e t o f f A w h e e l ) ) ) ) )
I 5 : ( I n t e n d E ( K n o w - H o w - t o A (U s e A w h e e l p u l l e r) ) )
D o m i n a n c e R e l a t i o n s h i p s :
I 1 D O M I 2
I 1 D O M I 3
I 1 D O M I 4
I 4 D O M I 5
S a t i s f a c t i o n - P r e c e d e n c e R e l a t i o n s h i p s :
I 2 S P I 3
I 2 S P I 4
I 3 S P I 4
Figure 6 . I n t e n t i o n a l s t r u c t u r e f o r th e t a s k - o r i e n t e d d i a l o g u e s e g m e n t .
C o m p u t a t i o n a l L i n g u i s t i c s , V o l u m e 1 2 , N u m b e r 3 , J u l y - S e p t e m b e r
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B a r b a r a J . G r o s z a n d C a n d a c e L . S i d n e r A t t e n t i o n , I n t e n t i o n s , a n d t h e S t r u c t u r e o f D i s c o u r s e
The dialogue includes a clear example of the influence
of discourse structure on referring expressions. The
phrase the screw in the center is used in (25) to refer to
the center screw of the wheelpuller, not one of the two
setscrews mentioned in (18). This use of the phrase is
possible because of the attentional state of the discourse
structure at the time the phrase is uttered.
4 PROCESSING ISSUES
In previous sections of the paper, we abstracted from the
cognitive states of the discourse participants. The various
components of discourse structure discussed so far are
properties of the discourse itself, not of the discourse
participants. To use the theory in constructing computa-
tional models requires determining how each of the indi-
vidual components projects onto the model of an
individual discourse participant. In this regard, the prin-
cipal issues include specifying
1. how the ICP indicates and the OCP recognizes the
beginning and end of a discourse segment,
2. how the OCP recognizes the discourse segment
purposes, and
3. how the focus space stack operates.
In essence, the OCP must judge for each utterance
whether it starts a new segment, ends the current one
(and possibly some of its embedding segments), or
contributes to the current one. The informatio n available
to the OCP for recognizing that an utterance starts a new
segment includes any explicit linguistic cues contained in
the utter ance (see Section 6 9 as well as the relatio nship
between its utterance-level intentions and the active DSPs
(i.e., those in some focus space that is still on the stack).
Likewise, the fact that an utterance ends a segment may
be indicated explicitly by linguistic cues or implicitly from
its utterance-level intentions and their relationship to
elements of the intentional structure. If neither of these is
the case, the utterance is part of the current segment.
Thus, intention recognition and focus space management
play key roles in processing. Moreover, they are also
related: the intentional structure is a primary factor in
determining focus space changes, and the focus space
structure helps constrain the intention recognition proc-
ess.
4.1 INTENTION RECOGNITIO N
The recognition of DP/DSPs is the central issue in the
computation al modeling of intentional structure. If, as
we have claimed, for the discourse to be coherent and
comprehensible, the OCP must be able to recognize both
the DP/DSPs 10 and relationships (dominanc e and satis-
faction-precedence) between them, then the question of
how the OCP does so is a crucial issue.
For the discourse as a whole, as well as for each of its
segments, the OCP must identify both the intention that
serves as the discourse segment purpose and its relation-
ship to other discourse-level intentions. In particular, the
OCP must be able to recognize which other DSPs that
specific intention dominates and is dominated by, and,
where relevant, with which other DSPs it has satisfac-
tion-pr ecedence relationships. Two issues that are
central to the recognition problem are what information
the OCP can utilize in effecting the recognition and at
what point in the discourse that information becomes
available.
An adequate computational model of the recognition
process depends critically on an adequate theory of
intention and action; this, of course, is a large research
problem in itself and one not restricted to matters of
discourse. The need to use such a model for discourse,
however, adds certain constraints on the adequacy of any
theory or model. Pollack (1986) describes several prop-
erties such theories and models must possess if they are
to be adequate for supporting recognition of intention in
single-utterance queries; she shows how current AI plan-
ning models are inadequate and proposes an alternative
planning formalism. The need to enable recognition of
discourse-level intentions leads to yet another set of
requirements.
As will become clear in what follows, the information
available to the OCP comes from a variety of sources.
Each of these can typically provide partial information
about the DSPs and their relationships. These s ources are
each partially constraining, but only in their ensemble do
they constrain in full. To the extent that more informa-
tion is furnished by any one source, commensurately less
is needed from the others. The overall processing model
must be one of constraint satisfaction that can operate on
partial information. It must allow for incrementally
constraining the range of possibilities on the basis of new
information that becomes available as the segment
progresses.
4.1.1 INFORMATION CONSTRAINING THE DSP
At least three different kinds of information play a role in
the determination of the DSP: specific linguistic markers,
utterance-level intentions, and general knowledge about
actions and objects in the domain of discourse. Eac h
plays a part in the OCP's recognition of the DSP and can
be utilized by the ICP to facilitate this recognition.
Cue phrases are the most distinguished linguistic
means that speakers have for indicating discourse
segment boundaries and conveying information about the
DSP. Recen t evidence by Hirschb erg and Pierre humber t
(i~986) suggests that certain intonational properties of
utterances also provide partial information about the DSP
relationships. Because some cue phrases may be used as
clausal connectors, there is a need to distinguish their
discourse use from their use in conveying propositional
conte nt at the utterance level. For example, the word bu
functions as a boundary marker in utterance (7) of the
discourse in Section 3.1, but it can also be used solely (as
in the current utterance) to convey propositional content
(e.g., the conjunction of two propositions) and serve to
connect two clauses within a segment.
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B a r b a r a J . G r o s z a n d C a n d a c e L . S i d n e r A t t e n t i o n , I n t e n t i o n s , a n d t h e S t r u c t u r e o f D i s c o u r s e
As discussed in Section 6, cue phrases can provide
information about dominance and satisfaction-prece-
dence relationships between segments' DSPs. However,
they may not completely specify which DSP dominates or
satisfaction-precedes the DSP of the segment they start.
Furthermore, cue phrases that explicitly convey informa-
tion only about the attentional structure (see Section 6)
may be ambiguous about the state to which attention is
to shift. For example, if there have been several inter-
ruptions (see Section 5), the phrase but anyway indicates
a return to some previously interrupted discourse, but
does not specify which one. Although cue phrases do not
completely specify a DSP, the information they provide is
useful in limiting the options to be considered.
The second kind of information the OCP has available
is the utterance-level intention of each utterance in the
discourse. As the discussion of the movies example
(Section 3.1) pointed out, the DSP may be identical to
the utterance-level intention of some utterance in the
segment. Alternatively, the DSP may combine the
intentions of several utterances, as is illustrated in the
following discourse segment:
I want you to ar range a trip for me to Palo Alto.
It will be for two weeks.
I only fly on TWA.
The DSP for this segment is, roughly, that the ICP
intends for the OCP to make (complete) trip arrange-
ments for the ICP to go to Palo Alto for two weeks,
under the constraint that any flights be on TWA. The
Gricean intentions for these three utterances are as
follows:
U t t e r a n c e I :
ICP intends that OCP believe that ICP
intends that OCP intend to make trip plans
for ICP to go to
Palo Alto
U t t e r a n c e 2 : ICP intends that OCP believe that ICP
intends OCP to believe that the trip will last
two weeks
U t t e r a n c e 3 :
ICP intends that OCP believe that ICP
intends OCP to believe that ICP flies only on
TWA
These intentions must be combined in some way to
produ ce the DSP. The proc ess is quite complex, since the
OCP must recognize that the reason for utterances 2 and
3 is not simply to have some new beliefs about the ICP,
but to use those beliefs in arranging the trip. While this
example fits the schema of a request followed by two
informings, schemata will not suffice to represent the
behavior as a general rule. A different sequence of utter-
ances with different utterance-level intentions can have
the same DSP; this is the case in the following segment:
S 1: Have I told you yet to arrange my trip to Palo Alto?
Remember that I will fly only on TWA. OK?
$2: OK.
$3: I'm planning on staying for two weeks.
It is possible for a sequence that consists of a request
followed by two informings not to result in a modifica-
tion of the trip plans. For example, in the following
sequence the third utterance results in changing the way
the arrangements are made, rather than constraining the
nature of the arrangements themselves.
I want you to arrange a two-week trip for me to Palo
Alto. I fly only on TWA. The rates go up tomorrow,
so you'll want to call today.
Not only is the contribution of utterance-level
intentions to DSPs complicated, but in some instances the
DSP for a segment may both constrain and be partially
determined by the Gricean intention for some utterance
in the segment. For example, the Gricean-intention for
utterance (15) in the movies example (Section 3.1) is
derived from a combination of facts about the utterance
itself, and from its place in the discourse. On the surfac e,
(15) appears to be a question addressed to the OCP; its
intention would be roughly that the ICP intends the OCP
to believe that the ICP wants to know how young people,
etc. But (15) is actually a rhetor ical questio n and has a
very different intention associated with it - namely, that
the ICP intends the OCP to believe proposition P2
(namely, that young people cannot drink in through their
eyes a continuous spectacle of intense and strained activ-
ity without harniful effects). In this example, this partic-
ular intention is also the primar y com pone nt of the DSP.
The third kind of information that plays a role in
determining the DP/DSPs is shared knowledge about
actions and objects in the domain of discourse. This
shared knowledge is especially important when the
linguistic markers and utterance-level intentions are
insufficient for determining the DSP precisely.
In Section 7 we introduce two relations, a s u p p o r t s
relation between propositions and a generates relation
between actions, and present two rules stating equiv-
alences; one links a dominance relation between two
DSPs with a supports relation between propositions and
the other links a dominance relation between DSPs to a
generates relation between actions. Use of these rules in
one direction allows for (partially) determining what
supports or generates relationship holds from the domi-
nance relationship. But the rules can be used in the oppo-
site direction also: if, from the content of utterances and
reasoning about the domain of discourse, a supports or
generates relationship can be determined, then the domi-
nates relationship between DSPs can be determined. In
such cases it is important to derive the dominance
relationship so that the appropriate intentional and atten-
tional structures are available for processing or determin-
ing the interpretation of the subsequent discourse.
From the perspective of recognition, a trade-off
implicit in the two equivalences is impor tant. If the ICP
makes the dominance relationship between two DSPs
explicit (e.g., with cue phrases), then the OCP can use
this information to help recognize the (ICP's beliefs
about the) supports relationship. Conversely, if the ICP's
utterances make clear the (ICP's beliefs about the)
supports or generates relationship, then the OCP can use
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B a r b a r a J . G r o s z a n d C a n d a e e L . S i t h a e r
A t t e n t i o n , I n t e n t i o n s , a n d t h e S t r u c t u r e o f D i s c o u r s e
t h i s i n f o r m a t i o n t o h e l p r e c o g n i z e t h e d o m i n a n c e
r e l a ti o n s h ip . A l t h o u g h i t i s m o s t h e l p fu l t o u s e th e d o m i -
n a n c e r e l a t i o n s h i p s t o c o n s t r a i n t h e s e a r c h f o r a p p r o p r i -
a t e s u p p o r t s a n d g e n e r a t e s r e l a t i o n s h i p s, s o m e t i m e s t h e s e
l a t t e r r e l a t i o n s h i p s c a n b e i n f e r r e d r e a s o n a b l y d i r e c t l y
f r o m t h e u t t e r a n c e s i n a. s e g m e n t u s i n g g e n e r a l k n o w -
l e d g e a b o u t t h e o b j e c t s a n d a c t i o n s i n t h e d o m a i n o f
d i s c o u r se . I t r e m a i n s a n o p e n q u e s t io n w h a t i n f e r e n c e s
a r e n e e d e d a n d h o w c o m p l e x i t w i l l b e t o c o m p u t e
s u p p o r t s a n d g e n e r a t e s r e l a t i o n s h i p s if t h e d o m i n a n c e
r e l a t i o n s h i p i s n o t d i r e c t l y i n d i c a t e d i n a d i s c o u r s e .
U t t e r a n c e s f r o m t h e m o v i e s e s s a y i l l u s t r a t e t h i s t r a d e -
o f f . I n u t t e r a n c e ( 9 ) , t h e p h r a s e in the f irs t p lace
e x p r e s s e s t h e d o m i n a n c e r e l a t i o n s h i p b e t w e e n D S P s o f
t h e n e w s e g m e n t D S 5 a n d t h e p a r e n t s e g m e n t D S 4 d i r e c t -
l y. B e c a u s e o f t he d o m i n a n c e r e l a t i o n s h ip ( a s w e l l as t h e
i n t e n t i o n s e x p r e s s e d i n t h e u t t e r a n c e s ) , t h e O C P c a n
d e t e r m i n e t h a t t h e I C P b e l i e v e s t h a t t h e p r o p o s i t i o n t h a t
t h e c o n t e n t o f t h e p l a y s i s n o t t h e b e s t p r o v i d e s s u p p o r t
f o r t h e p r o p o s i t i o n t h a t t h e r e s u l t o f i n d i s c r i m i n a t e m o v i e
g o i n g i s h a r m f u l . H e n c e d e t e r m i n i n g d o m i n a n c e y i e l ds
t h e s u p p o r t r e l a t io n . T h e s u p p o r t r e l a t i o n c a n a ls o y i e l d
d o m i n a n c e . U t t e r a n c e s ( 1 2 ) - ( 1 4 ) , w h i c h c o m p r i s e D S 7,
a r e n o t e x p li c i tl y m a r k e d f o r a d o m i n a n c e r e l a t i on . I t c a n
b e i n f e r r e d f r o m t h e f a c t t h a t t h e p r o p o s i t i o n s i n
( 1 2 ) - ( 1 4 ) p r o v i de s u p p o r t f o r th e p r o p o s i t io n e m b e d d e d
i n D S P 6 ( t h a t i s , t h a t t h e s t o r i e s i n m o v i e s a r e e x c i t i n g
a n d o v e r - e m o t i o n a l ) t h a t D S P 6 d o m i n a t e s D S P 7 .
F i n a ll y , t h e m o r e i n f o r m a t i o n a n I C P s u p p l i e s e x p l ic i t -
l y i n t h e a c t u a l u t t e r a n c e s o f a d i s c o u r s e , t h e l e s s r e a s o n -
i n g a b o u t d o m a i n i n f o r m a t i o n a n O C P h a s t o d o t o
a c h i e v e r e c o g n i ti o n . C o h e n ( 1 9 8 3 ) h a s m a d e a si m i l a r
c l a i m r e g a r d i n g t h e p r o b l e m o f r e c o g n i z i n g t h e r e l a t i o n -
s h i p b e t w e e n o n e p r o p o s i t i o n a n d a n o t h e r .
4 . 1 .2 W H E N I S T H E I N T E N T I O N R E C O G N I Z E D ?
A s d i s c u s s e d i n S e c t i o n 2 . 2 , t h e i n t e n t i o n a l s t r u c t u r e
e v o l v e s a s th e d i s c o u r s e d o e s . B y t h e s a m e t o k e n , t h e
d i s c o u r s e p a r t i c i p a n t s ' m e n t a l - s t a t e c o r r e l a t e s o f th e
i n t e n t i o n a l s t ru c t u r e a r e n o t p r e b u i l t; n e i t h e r p a r t i c i p a n t
m a y h a v e a c o m p l e t e m o d e l o f t h e i n t e n t i o n a l s t r u c t u re
i n m i n d u n t il t h e d i s c o u r s e i s c o m p l e t e d . T h e d o m i -
n a n c e r e l a t i o n s h i p s t h a t a c t u a l l y s h a p e t h e i n t e n t i o n a l
s t r u c t u r e c a n n o t b e k n o w n a p r i o r i , b e c a u s e t h e s p e c i f i c
i n t e n t i o n s t h a t w i ll c o m e i n t o p l a y a r e n o t k n o w n ( n e v e r
b y t h e O C P , h a r d l y e v e r b y t h e I C P ) u n t i l t h e u t t e r a n c e s
i n t h e d i s c o u rs e h a v e b e e n m a d e . A l t h o u g h i t i s a s s u m e d
t h a t t h e p a r t i c i p a n t s ' c o m m o n k n o w l e d g e i n c l ud e s 11
e n o u g h i n f o r m a t i o n a b o u t t h e d o m a i n t o d e t e r m i n e v a r i -
o u s r e l a t i o n s h ip s s u c h a s s u p p o r t s a n d g e n e r a t e s , i t is n o t
a s s u m e d t h a t , p r i o r t o a d i s c o u r s e , t h e y a c t u a l l y h a d
i n f e r r e d a n d a r e a w a r e o f a l l t h e r e l a t i o n s h i p s t h e y w i l l
n e e d f o r t h a t d i s c o u r s e .
B e c a u s e a n y o f t h e u t t e r a n c e s i n a s e g m e n t m a y
c o n t r i b u t e i n f o r m a t i o n r e l e v a n t t o a c o m p l e t e d e t e r m i -
n a t i o n o f t h e D S P , t h e r e c o g n i t i o n p r o c e s s i s n o t
c o m p l e t e u n ti l t h e e n d o f t h e s e g m e n t . H o w e v e r , t h e O C P
m u s t b e a b l e t o r e c o g n i z e a t l e a s t a g e n e r a l i z a t i o n o f t h e
D S P so t h a t h e c a n m a k e t h e p r o p e r m o v e s w i t h r e s p e c t
t o t h e a t t e n t i o n a l s t r u c t u r e . T h a t i s , s o m e c o m b i n a t i o n o f
e x p l ic i t i n d i c a t o r s a n d i n t e n t i o n a l a n d p r o p o s i t i o n a l
c o n t e n t m u s t a l l o w t h e O C P t o a s c e r t a i n w h e r e t h e D S P
w i l l f i t i n t h e i n t e n t i o n a l s t r u c t u r e a t t h e b e g i n n i n g o f a
s e g m e n t , e v e n i f t h e s p e c i f i c i n t e n t i o n t h a t i s t h e D S P
c a n n o t b e d e t e r m i n e d u n t i l t h e e n d o f t h e s e g m e n t .
U t t e r a n c e ( 1 5 ) i n t h e m o v i e s e x a m p l e i l l u s t ra t e s t h is
p o in t . T h e a u t h o r w r i te s , H o w c a n o u r y o u n g p e o p l e
d r i n k i n t h r o u g h t h e i r e y e s a c o n t i n u o u s s p e c t a c l e o f
i n t e n s e a n d s t r a i n e d a c t i v i t y a n d f e e l i n g w i t h o u t h a r m f u l
e f f e c t s ? T h e p r i m a r y i n t e n t i o n 1 2 i s d e r i v e d f r o m t h i s
u t t e r a n c e , b u t t h i s c a n n o t b e d o n e u n t i l v e r y l a t e in t h e
d i s c o u r s e s e g m e n t [ s i n c e ( 1 5 ) o c c u r s a t t h e e n d o f D S 2] .
F u r t h e r m o r e , t h e s e g m e n t f o r w h i c h 1 2 i s p r i m a r y h a s
c o m p l e x e m b e d d i n g o f o t h e r s eg m e n t s . U t t e r a n c e ( 1 6 ) ,
i n t e n t i o n I 0 , a n d D S 0 c o n s t i t u t e a n o t h e r e x a m p l e o f t h e
e x p r e s s i o n o f a p r i m a r y i n t e n t i o n l a t e i n a d i s c o u r s e
s e g m e n t . I n t h a t c a se , I 0 c a n n o t b e c o m p u t e d u n t i l ( 1 6 )
h a s b e e n r e a d , a n d ( 1 6 ) i s n o t o n l y t h e l a s t u t t e r a n c e i n
D S 0, b u t is o n e t h a t c o v e r s t h e e n t i r e e s s a y . I f a n O C P
m u s t r e c o g n i z e a D S P t o u n d e r s t a n d a s e g m e n t , t h e n w e
a s k : h o w d o e s t h e O C P r e c o g n i z e a D SP w h e n t h e u t t e r -
a n c e f r o m w h i c h i t s p r i m a r y i n t e n t i o n i s d e r i v e d c o m e s s o
l a t e in t h e s e g m e n t ?
W e c o n j e c t u r e w i t h r e g a r d t o s u c h s e g m e n t s a s D 2 o f
t h e m o v i e s e s s a y t h a t t h e p r i m a r y i n t e n t i o n ( e .g . , 1 2) m a y
b e d e t e r m i n e d p a r t i a l ly ( a n d h e n c e a g e n e r a l i z e d v e r s i o n
b e c o m e r e c o g n i z a b l e ) b e f o r e t h e p o i n t a t w h i c h i t i s
a c t u a l l y e x p r e s s e d i n t h e d i s c o u r s e . W h i l e t h e D P / D S P
m a y n o t b e e x p r e s s e d e a r l y , t h e r e i s s t i l l part ia l in forma-
tion a b o u t it . T h i s p a r t i a l i n f o r m a t i o n o f t e n s u f f i c e s t o
e s t a bl i sh d o m i n a n c e ( o r s a t i s f a c t io n - p r e c e d e n c e )
r e l a t i o ns h i p s f o r a d d i t i o n a l s e g m e n t s . A s t h e s e l a t t e r a r e
p l a c e d i n t h e h i e r a r c h y , t h e i r D S P s c a n p r o v i d e f u r t h e r
p a r t i a l i n f o r m a t i o n f o r t h e u n d e r s p e c i f i e d D S P . F o r
e x a m p l e , e v e n t h o u g h t h e i n t e n t i o n I 0 i s e x p r e s s e d
d i r e c t l y o n l y in t h e l a s t u t t e r a n c e o f t h e m o v i e s e s s a y ,
u t t e r a n c e ( 4 ) e x p r e s s e s a n i n t e n t i o n t o k n o w w h e t h e r p
o r ~ p i s t r u e ( i . e . , w h e t h e r o r n o t p a r e n t s s h o u l d l e t c h i l -
d r e n s e e m o v i e s o f t e n a n d w i t h o u t c lo s e m o n i t o r i n g ) . I 0
i s a n i n t e n t i o n t o b e l i e v e , w h o s e p r o p o s i t i o n i s a g e n e r -
a l i z a t i o n o f t h e ~ p e x p r e s s e d i n (4 ) . C o n s i d e r a l s o t h e
p r i m a r y i n t e n t i o n 14 . I t o c c u r s in a s e g m e n t e m b e d d e d
w i t h i n D S 2 , i s m o r e g e n e r a l t h a n 1 2, b u t i s a n a p p r o x i -
m a t i o n t o it . I t w o u l d n o t b e s u r p r i s i n g t o d i s c o v e r t h a t
O C P s c a n i n f a c t p r e d i c t s o m e t h i n g c l o s e t o 1 2 o n t h e
b a s i s o f 14 , u t t e r a n c e s ( 9 ) - ( 1 4 ) , a n d t h e p a r t i a l d o m i -
n a n c e h i e r a r c h y a v a i l a b l e a t e a c h p o i n t i n t h e d i s c o u r s e .
4 . 2 U S E O F T H E A T Y E N T IO N A L S T A T E M O D E L
T h e f o c u s s p a c e s t r u c t u r e e n a b l e s c e r t a i n p r o c e s s i n g
d e c i s i o n s t o b e m a d e l o c a l l y . I n p a r t i c u l a r , i t l i m i t s t h e
i n f o r m a t i o n t h a t m u s t b e c o n s i d e r e d i n r e c o g n i z i n g t h e
D S P a s w e ll a s t h a t c o n s i d e r e d i n id e n t i f y i n g t h e r e f e r e n t s
o f c e r t a i n c l a s s e s o f d e f i n i te n o u n p h r a s e s .
1 9 0
C o m p u t a t i o n a l L i n g u i s ti c s , V o l u m e 1 2 , N u m b e r 3 , J u l y - S e p t e m b e r
1 9 8 6
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B a r b a r a J . G r o s z a n d C a n d a c e L . S i d n e r A t t e n t i o n , I n t e n t i o n s , a n d t h e S t r u c t u r e o f D i s c o u r s e
A primary role of the focus space stack is to constrain
the range of DSPs considered as candidates for domi-
nation or satisfaction-precedence of the DSP of the
curre nt segment. Only those DSPs in some space on the
focusi ng stack are viable prospects. As a result of this
use of the focusing structure, the theory predicts that this
decision will be a local one with respect to attentional
state. Because two focus spaces may be close to each
other in the attentional structure without the discourse
segments they arise from necessarily being close to one
another and vice versa, this prediction corresponds to a
claim that locality in the focusing structure is what
matters to determination of the intentional structure.
A second role of the focusing structure is to constrain
the OCP's search for possible referents of definite noun
phrases and pronouns . To illustrate this role, we will
consider the phrase
the screw in the center
in utterance
(25) of the task-oriented dialogue of Section 3. The
focus stack configuration when utterance (25) is spoken
is shown in Figure 7. The stack contains (in bott om- to-
top order) focus spaces FSI, FS4, and FS5 for segments
DS1, DS4, and DS5, respective ly. Fo r DS5 the wheel pul-
ler is a focused entity, while for DS4 the two setscrews
are (because they are explicitly mentioned). The entities
in FS5 are considered before those in FS4 as potential
referents. The wheelpuller has three screws: two small
screws fasten the side arms, and a large screw in the
center is the main functioning part. As a result, this large
screw is implicitly in focus in FS5 (Grosz 1977) and thus
identified as the referent without the two setscrews ever
being considered.
Attentional state also constrains the search for refer-
ents of pronouns. Because pronouns contain less explicit
information about their referents than definite
descriptions, additional mechanisms are needed to
account for what may a nd may not be pronominalized in
the discourse. One such mechanis m is centering (which
we previously called immediate focusing; Grosz, Joshi,
and Weinstein 1983; Sidner 1979).
Centering, like focusing, is a dynamic behavior, but is
a more local phenom enon. In brief, a backwar d-looki ng
center is associated with each utterance in a discourse
segment; of all the focused elements the backward-look-
ing center is the one that is central in that utterance (i.e.,
the uttering of the particular sequence of words at that
point in the discourse). A combination of syntactic,
semantic, and discourse information is used to identify
the backward-looking center. The fact that some entity is
the backward-looking center is used to constrain the
search for the referent of a pronoun in a subsequent
uttera nce. Note that unlike the DSP, which is con sta nt
for a segment, the backward-looking center may shift:
different entities may become more salient at different
points in the segment.
The presence of both centers and DSPs in this theory
leads us to an intriguing conjecture: that topi c is a
concept that is used ambiguously for both the DSP of a
segment and the center. In the literature the concept of
topi c has appeare d in many guises. In syntactic form it
is used to describe the preposing of syntactic constituents
in English and the wa marking in Japanese. Resear ch-
ers have used it to describe the sentence topic (i.e., what
the sentence is about; Firbas 1971, Sgall, Haji~ov~, and
SETSCREWS 3
FLYWHEELIo
DSP 1
FS1
SCREW 1
SCREW 2
DSP 2
FS2
SETSCREWS 3
FLYWHEELIo
DSP 1
FS1
ALLEN WRENCH 9
KEYS14
DSP 3
FS3
SETSCREWS 3
FLYWHEELlo
DSP 1
FS1
WHEEL PULLER 8
DSP 5
FS5
SETSCREWS 3
FLYWHEELIo
DSP 4
FS4
SETSCREWS 3
FLYWHEELlo
DSP 1
FS1
t i m e
Figure 7. Focus Stack Transitions Leading up to Utteranc e (25).
C o m p u t a t i o n a l L i n g u i st i cs , V o l u m e 1 2 , N u m b e r 3 , J u l y - S e p t e m b e r 1 9 8 6 1 9 1
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Barbara J . Grosz and Candace L . S idner At tent ion , In tent ions , and the S tructure of Discourse
B e n e s o v a 1 9 7 3 ) , a n d a s a p r a g m a t i c n o t i o n ( R e i n h a r t
1 9 8 1 ) ; o t h e r s w a n t t o u s e t h e t e r m f o r d i s c o u r s e t o p i c ,
e i t h e r t o m e a n w h a t t h e d i s c o u r s e i s a b o u t , o r t o b e
d e f i n e d a s t h o s e p r o p o s i t i o n ( s ) t h e I C P p r o v i d e s o r
r e q u e s t s n e w i n f o r m a t i o n a b o u t ( s e e R e i n h a r t ( 1 9 8 1 ) f o r
a r e v i e w o f m a n y o f t h e n o t i o n s o f a b o u t n e s s a n d t o p i c ) .
I t a p p e a r s t h a t m a n y o f t h e d e s c r i p t i o n s o f s e n t e n c e t o p i c
c o r r e s p o n d ( t h o u g h n o t a l w a y s ) t o c e n t e r s , w h i l e
d i s c o u r s e t o p i c c o r r e s p o n d s t o t h e D S P o f a s e g m e n t o r o f
t h e d i s c o u r s e .
5 APPLICATI ON OF THE THEORY: INTERRUPTIONS
I n t e r r u p t i o n s i n d i s c o u r s e s p o s e a n i m p o r t a n t t e s t o f a n y
t h e o r y o f d i s c o u r s e s t r u c tu r e . B e c a u s e p r o c e s s i n g a n
u t t e r a n c e r e q u i r e s a s c e r t a i n i n g h o w i t f i ts w i t h p r e v i o u s
d i s c o u r s e , i t i s c r u c i a l t o d e c i d e w h i c h p a r t s o f t h e p r e v i -
o u s d i s c o u r s e a r e r e l e v a n t t o i t , a n d w h i c h c a n n o t b e .
I n t e r r u p t i o n s , b y d e f i n it i o n , d o n o t f i t; c o n s e q u e n t l y t h e i r
t r e a t m e n t h a s i m p l i c a t i o n s f o r t h e t r e a t m e n t o f t h e
n o r m a l f l o w o f d i s c o u r se . I n t e r r u p t i o n s m a y t a k e m a n y
f o r m s - s o m e a r e n o t a t a ll r e l e v a n t t o t h e c o n t e n t a n d
f l o w o f t h e i n t e r r u p t e d d i s c o u r s e , o t h e r s a r e q u i t e r e l e -
v a n t , a n d m a n y f a l l s o m e w h e r e i n b e t w e e n t h e s e
e x t r e m e s . A t h e o r y m u s t d i f f e r e n ti a t e t h e se c a s e s a n d
e x p l a i n ( a m o n g o t h e r t hi n g s ) w h a t c o n n e c t i o n s e x i s t
b e t w e e n t h e m a i n d is c o u r s e a n d t h e in t e r r u p t i o n , a n d
h o w t h e r e l a t i o n s h i p b e t w e e n t h e m a f f e c t s t h e p r o c e s s i n g
o f t h e u t t e r a n c e s i n b o t h .
T h e i m p o r t a n c e o f d i s t i n g u i s h i n g b e t w e e n i n t e n t i o n a l
s t r u c t u r e a n d a t t e n t i o n a l s t a t e i s e v i d e n t in t h e t h r e e
e x a m p l e s c o n s i d e r e d i n S u b s e c t i o n s 5 . 2 , 5 .3 , a n d 5 . 4.
T h e d i s t i n c t i o n a l s o p e r m i t s u s t o e x p l a i n a t y p e o f
b e h a v i o r d e e m e d b y o t h e r s t o b e s i m i la r - s o - c a l l e d
s e m a n t i c r e t u r n s - a n i s s u e w e e x a m i n e i n S u b s e c t i o n
5 .5 .
T h e s e e x a m p l e s d o n o t e x h a u s t t h e t y p e s o f i n t e r -
r u p t i o n s t h a t c a n o c c u r i n d i s c o u r s e . T h e r e a r e o t h e r
w a y s t o v a r y t h e e x p l i c i t l i n g u i s t i c ( a n d n o n l i n g u i s t i c )
i n d i c a t o r s u s e d t o i n d i c a t e b o u n d a r i e s , t h e r e l a t i o n s h i p s
b e t w e e n D S P s , a n d t h e c o m b i n a t i o n s o f f o c u s s p a c e
r e l a t i o n s h i p s p r e s e n t . H o w e v e r , t h e e x a m p l e s p r o v i d e
i l l u s t r a t i o n s o f i n t e r r u p t i o n s a t d i f f e r e n t p o i n t s a l o n g t h e
s p e c t r u m o f r e l e v a n c y t o t h e m a i n d i s c o ur s e . B e c a u s e
t h e y c a n b e e x p l a i n e d m o r e a d e q u a t e l y b y t h e t h e o r y o f
d i s c o u r s e s t r u c t u re p r e s e n t e d h e r e t h a n b y p r e v i o u s t h e o -
r i es , t h e y s u p p o r t t h e i m p o r t a n c e o f t h e d i s t i n c ti o n s w e
h a v e d r a w n .
5.1 PRELIMINARY DEFINI TIONS
F r o m a n i n t u i t i v e v i e w , w e o b s e r v e t h a t i n t e r r u p t i o n s a r e
p i e c e s o f d i s c o u r s e t h a t b r e a k t h e f l o w o f th e p r e c e d i n g
d i s c o u r se . A n i n t e r r u p t i o n i s i n s o m e w a y d is t i n ct f r o m
t h e r e s t o f t h e p r e c e d i n g d i s c o u r s e ; a f t e r t h e b r e a k f o r
t h e i n t e r r u p t i o n , t h e d i s c o u r s e r e t u r n s t o t h e i n t e r r u p t e d
p i e c e o f d i s c o u r se . I n th e e x a m p l e b e l o w , f r o m P o l a n y i
a n d S c h a ( f o r t h c o m i n g ) , t h e r e a r e t w o ( s e p a r a t e )
d i s c o u r s e s , D 1 i n d i c a t e d i n n o r m a l t y p e , a n d D 2 i n i t a l i c s .
D 2 i s a n i n t e r r u p t i o n t h a t b r e a k s t h e f l o w o f D 1 a n d i s
d i s t i n c t f r o m D 1.
D I : J o h n c a m e b y
a n d l e f t t h e g r o c e r i e s
D 2 : Stop that
you kids
D I : a n d I p u t t h e m a w a y
a f t e r h e l e f t
U s i n g t h e t h e o r y d e s c r i b e d i n p r e v i o u s s e c t i o n s , w e
c a n c a p t u r e t h e a b o v e i n tu i t i on s a b o u t t h e n a t u r e o f
i n t e r r u p t i o n s w i t h t w o s l ig h t l y d i f f e r e n t d e f i n i t i o n s . T h e
s t r o n g d e f i n i t io n h o l d s f o r t h o s e i n t e r r u p t i o n s w e c l a s s i f y
a s t r u e in t e r r u p t i o n s a n d d i g r e s s io n s , w h i l e t h e w e a k e r
f o r m h o l d s f o r t h o s e t h a t a r e f l a s h b a c k s . T h e t w o d e f i -
n i t i o n s a r e a s f o l l o w s :
Strong def ini t ion: A n i n t e r r u p t i o n i s a d i s c o u r s e
s e g m e n t w h o s e D S P is n o t d o m i n a t e d n o r s a t i s f a c -
t i o n - p r e c e d e d b y t h e D S P o f a n y p r e c e d i n g s e g m e n t .
W e a k d e f i n i t i o n : A n i n t e r r u p t i o n i s a d i s c o u r s e
s e g m e n t w h o s e D S P is n o t d o m i n a t e d n o r s a t i s f a c -
t i o n - p r e c e d e d b y t h e D S P o f th e i m m e d i a t e l y p r e c e d -
i n g s e g m e n t .
N e i t h e r o f t h e a b o v e d e f i n i t i o n s i n c l u d e s a n e x p l i c i t
m e n t i o n o f o u r in t u i ti o n th a t t h e r e i s a r e t u r n t o t h e
i n t e r r u p t e d d i s c o u r s e a f t e r a n in t e r r u p t i o n . T h e r e t u r n i s
a n e f f e c t o f t h e n o r m a l p r o g r e s s o f a c o n v e r s a t i o n . I f w e
a s s u m e a f o c u s s p a c e i s n o r m a l l y p o p p e d f r o m t h e f o c u s
s t a c k i f a n d o n l y i f a s p e a k e r h a s s a t i s f i e d t h e D S P o f i t s
c o r r e s p o n d i n g s e g m e n t , t h e n i t n a t u r a l l y f o l l o w s b o t h
t h a t t h e f o c u s s p a c e f o r t h e i n t e r r u p t i o n w i l l b e p o p p e d
a f t e r t h e i n t e r ru p t i o n , a n d t h a t t h e f o c u s s p a c e f o r t h e
i n t e r r u p t e d s e g m e n t w i l l b e a t t h e t o p o f t h e s t a c k
b e c a u s e i t s D S P i s y e t t o b e s a t i s f i e d .
T h e r e a r e o t h e r k i n d s o f d i s c o u r s e s e g m e n t s t h a t o n e
m a y w a n t t o c o n s i d e r i n li g h t o f t h e i n t e r r u p t i o n c o n t i n -
u u m a n d t h e s e d e f in i t io n s . C l a r i f i c a t i o n d i a l o g u e s ( A l l e n
1 9 7 9 ) a n d d e b u g g i n g e x p l a n a t i o n s ( S i d n e r 1 9 8 3 ) a r e t w o
s u c h p o s si b i l it i e s . B o t h o f t h e m , u n l i k e th e i n t e r r u p t i o n s
d i s c u s s e d h e r e , s h a r e a D S P w i t h t h e i r p r e c e d i n g s e g m e n t
a n d t h u s d o n o t c o n f o r m t o o u r d e f i n i t i o n o f i n t e r r u p t i o n .
T h e s e k i n d s o f d is c o u r s e s m a y c o n s t i t u t e a n o t h e r g e n e r a l
c l a s s o f d i s c o u r s e s e g m e n t s t h a t , l i k e i n t e r ru p t i o n s , c a n
b e a b s t r a c t l y d e f i n e d .
5.2 TYPE 1: TRUE INTERRUPTIONS
T h e f i rs t k i n d o f i n t e r r u p t i o n i s t h e t r u e i n t e r r u p t i o n ,
w h i c h f o l l o w s t h e s t r o n g d e f i n i t i o n o f i n t e r r u p t i o n s . I t i s
e x e m p l i f i e d b y t h e i n t e r r u p t i o n g i v e n in t h e p r e v i o u s
s u b s e c t i o n . D i s c o u r s e s D 1 a n d D 2 h a v e d is t i nc t , u n r e -
l a te d p u r p o s e s a n d c o n v e y d i f f e r e n t i n f o r m a t i o n a b o u t
p r o p e r t i e s , o b j e c t s , a n d r e l a t io n s . S i n c e D 2 o c c u r s w i t h i n
D 1 , o n e e x p e c t s t h e d i s c o u rs e s t r u c t u r e s f o r t h e t w o
s e g m e n t s to b e s o m e h o w e m b e d d e d a s we ll . T h e t h e o r y
d e s c r i b e d i n t h i s p a p e r d i f f e r s f r o m P o l a n y i a n d S c h a ' s
( 1 9 8 4 ; a n d o t h e r m o r e r a d i c a l l y d i f f e r e n t p r o p o s a l s a s
w e l l; e. g ., L i n d e a n d G o g u e n 1 9 7 8 , C o h e n 1 9 8 3 , R e i c h -
192
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B a r b a r a J . G r o s z a n d C a n d a c e L . S i d n e r A t t e n t i o n , I n t e n t i o n s , a n d t h e S t r u c t u r e o f D i s c o u r s e
man-Adar 1984) because the embedding occurs only in
the attentional structure. As shown in Figure 8, the
focus space for D2 is pushed onto the stack above the
focus space for D1, so that the focus space for D2 is
more salient than the one for D 1, until D2 is comple ted.
The intentional structures for the two segments are
distinct. There are two DP/DSP structures for the utter-
ances in this sequence - one for those in D1 an d the
other for those in D2. It is not necessary to relate these
two; indeed, from an intuitive point of view, they are not
related.
The focusing structure for true interruptions is differ-
ent from that for the normal embedding of segments,
because the focusing boundary between the interrupted
discourse and the in terru ption is impene trable . 12 (This is
depicted in the figure by a line with intersecting hash
marks betwee n focus spaces). The impenetrable bound a-
ry between the focus spaces prevents entities in the spac-
es below the boundary from being available to the spaces
above it. Because the second discourse shifts attention
totally to a new purpose (and may also shift the identity
of the intended hearers), the speaker cannot use any
DISCOURCESEGMENTS
FOCUSSPACESTACK
DOMINANCE HIERARCHY
DI : JOHNCAME BYAND
LEFT THE GROCERIES \
D2: STOP THA T YOU KIDS
D1 cont: AND I PUT THEM
AWAY AFTER HE LEFT
\
A
/
\
\
KIDS 1
KIDS 1 STOP ...
DSP 2
FS5
; - , - , ; - , - , , - . - - . ; - r. t
JOHN 10
GROCERIES14
JOHN'S COMING 15
DSP 1
FS4
(EMPTY)
a )
DISCOURSE SEGMENTS
FOCUS SPACE STACK
DOMINANCE HIERARCHY
f~
DI : JOHN CAME BY AND
LEFT THE GROCERIES
D2: STOP THA T YOU KIDS
D1 cont: AND I PUT THEM
AWAY AFTER HE LEFT
/
/
JOHNlo
GROCERIES14
JOHN'SCOMING15
DSP 1
FS4
(EMPTY)
b )
F i g u r e
8. The structures of a true interruption.
C o m p u t a t i o n a l L i n g u i s t ic s , V o l u m e 1 2 , N u m b e r 3 , J u l y - S e p t e m b e r 1 9 8 6 1 9 3
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B a r b a r a J . G r o s z a n d C a n d a c e L . S i d n e r A t t e n t i o n , I n t e n t i o n s , a n d t h e S t r u c t u r e o f D i s c o u r s e
referential expressions during it that depend on the
accessibility of entities fro m the first discourse. Since the
boundary between the focus space for D1 and the one
for D2 is impenetrable, if D2 were to include an utter-
ance such as
p u t t h e m a w a y ,
the pronoun would have to
refer deictically, and not anaphorically, to the groceries.
In this sample discourse, however, D1 is resumed
almost immediately. The pronoun
t h e m
in
a n d I p u t t h e m
a w a y
cannot refer to the children (the focus space for D2
has been popped from the stack), but only to the
groceries. For this to be clear to the OCP, the ICP must
indicate a retur n to D 1 explicitly. One linguistic indicator
in this example is the change of mood from imperative.
Indicators that the
s to p t h a t
utterance is an interruption
include the change to imperative mood and the use of the
vocative (Polanyi and Scha 1983). Two other indicators
may be assumed to have been present at the time of the
discourse - a chang e of into natio n (imagine a slightly
shrill tone of command with an undercurrent of annoy-
ance) and a shift of gaze (toward and then away from
the kids). It is also possible that the type of pause pres-
ent in such cases is evidence of the interruption, but
further research is needed to establish whether this is
indeed the case.
In contrast to previous accounts, we are not forced to
integrate these two discourses into a single grammatical
structure, or to answer questions about the specific
relationship between segments D2 and D1, as in
Reichman's model (Reichman-Adar 1984). Instead, the
intuition that readers have of an embedding in the
discourse structure is captured in the attentional state by
the stacking of focus spaces. In addition, a read er's intui-
tive impression of the distinctness of the two segments is
captured in their different intentional (DP/DSP) struc-
tures.
5 .3 T Y P E 2 : F L A S H B A C K S A N D F I L L IN G IN M I S S I N G P L A C E S
Sometimes an ICP interrupts the flow of discussion
because some purposes, propositions, or objects need to
be brought into the discourse but have not been: the ICP
forgot to include those entities first, and so must now go
back and fill in the missing inform ation. A flashback
segment occurs at that point in the discourse. The flash-
back is defined as a segment whose DSP satisfaction-pre-
cedes the interrupted segment and is dominated by some
othe r segme nt's DSP. Henc e, it is a specialization of the
weak definition of interruptions. This type of inter-
ruptio n differs fro m true interruptions both intentionally
and linguistically: the DSP for the flashback bears some
relationship to the DP for the whole discourse. The
linguistic indicator of the flashback typically includes a
comm ent about something going wrong. In addition the
audience always remains the same, whereas it may
change for a true interruption (as in the example of the'
previous section).
In the example below, taken from Sidner (1982), the
ICP is instructing a mock-up system (mimicked by a
person) about how to define and display certain informa-
tion in a particular knowledge-representation language.
Again the interruption is indicated by italics.
OK. Now how do I say that Bill is
W h o o p s I f o r g o t a b o u t A B C .
I n e e d a n i n d i v id u a l c o n c e p t f o r t h e c o m p a n y A B C
. . .[ r e m a i n d e r o f d i s c o u r se s e g m e n t o n A B C ] . . .
Now back to Bill. How do I say that Bill is an employee
of ABC?
The DP for the larger discourse from which this
sequence was taken is to provide information about vari-
ous companies (including ABC) and their employees.
The oute r segm ent in this example - DBill - has a DSP -
D S P B i l l - to tell about Bill, while the inner segment -
D A B C - - has a D S P - D S P A B C -- t o convey certain infor-
mation about ABC. Because of the nature of the infor-
mation being told, there is order in the final structure of
the DP/DSPs: information about ABC must be conveyed
before all of the information abou t Bill can be. The ICP
in this instance does not realize this constraint until after
he begins. The flas hbac k interruption allows him to
s a t i s f y D S P A B C while suspending satisfaction of D S P B i l l
(which he then resumes). Hence, there is an intentional
structure rooted at DP and with
D S P A B C
and
D S P B i u a s
o rd ered
sister nodes. The following three relationships
hold betwee n the differ ent DSPs:14
DP DOM DSPABC
DP DOM DSPBill
DSPABC SP DSPBill
This kind of interruption is distinct from a true inter-
ruption because there is a connection, although indirect,
between the DSPs for the two segments. Furthermore,
the linguistic features of the start of the interruption
signify that there is a precedence relation between these
DSPs (and hence that the correc tion is necessary). Flash-
backs are also distinct from normally embedded
discourses because of the precedence relationship
between the DSPs for the two segments and the order in
which the segments occur.
The available linguistic data permit three possible
attentional states as appropriate models for flashback-
type interruptions: one is identical to the state that would
ensue if the flashback segment were a normally embed-
ded segment, the second resembles the model of a true
interruption, and the third differs from the others by
requiring an auxiliary stack. An example of the stack for
a normally embedded sequence is given in Section 4.2
Figure 9 illustrates the last possibility. The focus space
for the flashbac k - FSABC -- is pushed onto the stack
after an appropriate number of spaces, including the
focus space for the outer segment - F S B i l l , have been
popped from the main stack and pushed onto an auxiliary
stack. All of the entities in the focus spaces remaining on
the main stack are normally accessible for reference, but
none of those on the auxiliary stack are. In the example
in the figure, entities in the spaces fro m FS A to FS B are
accessible as well (though less salient than) those ir/
1 9 4
C o m p u t a t i o n a l L i n g u i s t i c s , V o l u m e 1 2 , N u m b e r 3 , J u l y - S e p t e m b e r
1 9 8 6
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B a r b a r a J . G r o s z a n d C a n d a c e L . S i d n e r A t t e n t i o n , I n t e n t i o n s , a n d t h e S t r u c t u r e o f D i s c o u r s e
s p a c e F S A B C . E v i d e n c e f o r t h is k i n d o f s t a c k b e h a v i o r
c o u l d c o m e f r o m d i s c o u r s e s i n w h i c h p h r a s e s i n t h e
s e g m e n t a b o u t A B C c o u l d r e f e r t o e n t i t i e s r e p r e s e n t e d i n
F S B , b u t n o t t o t h o s e i n F S B i u o r F S C . A f t e r a n e x p l i c i t
i n d i ca t i o n t h a t t h e re i s a r e tu rn t o D S P B i l l ( e . g . , t h e Now
back to Bill u s e d i n t h i s e x a m p l e ) , a n y f o c u s s p a c e s l e f t
o n t h e s t a c k f r o m t h e f l a s h b a c k a r e p o p p e d o f f , a n d a l l
s p a c e s o n t h e a u x i l i a r y s t a c k ( i n c l u d i n g F SB il l ) a r e
r e t u r n e d t o t h e m a i n s t a c k . N o t e , h o w e v e r , t h a t t h i s
m o d e l d o e s n o t p r e c l u d e t h e p o s s i b i l i t y o f a r e t u r n t o
s o m e s p a c e b e t w e e n F S A a n d F S B b e f o r e p o p p i n g t h e
a u x i li a r y s t a c k . W h e t h e r t h e r e a r e d i s c o u r s e s t h a t i nc l u d e
s u c h a r e t u r n a n d a r e d e e m e d c o h e r e n t i s a n o p e n q u e s -
t i o n .
T h e a u x i l i a r y s t a c k m o d e l d i f f e r s f r o m t h e o t h e r t w o
m o d e l s b y t h e r e f e r e n c e s p e r m i t t e d a n d b y t h e s p a c e s
t h a t c a n b e p o p p e d t o . G i v e n t h e i n i t i a l c o n f i g u r a t i o n i n
F i g u r e 9 , i f t h e s e g m e n t w i t h D SP A B C w e r e n o r m a l l y
e m b e d d e d , F S AB C w o u l d j u s t b e a d d e d t o t h e t o p o f t h e
s t a c k . I f i t w e r e a t r u e i n t e r r u p t i o n , t h e s p a c e w o u l d a l s o
' b e a d d e d t o t h e s t a c k , b u t w i t h a n i m p e n e t r a b l e b o u n d a -
r y b e t w e e n i t a n d F S B il l. I n t h e n o r m a l s t a c k m o d e l , e n t i -
t i e s i n t h e s p a c e s l o w e r i n t h e s t a c k w o u l d b e a c c e s s i b l e ;
i n t h e t r u e i n t e r r u p t i o n t h e y w o u l d n o t . I n e i t h e r o f t h e s e
t w o m o d e l s , h o w e v e r , F SB ill w o u ld b e t h e s p a c e r e t u r n e d
t o f i r s t . T h e a u x i l i a r y s t a c k m o d e l i s o b v i o u s l y m o r e
c o m p l i c a t e d t h a n t h e o t h e r t w o a l te r n a t i v e s . W h e t h e r it
( o r s o m e e q u i v a l e n t a l t e r n a t i v e ) i s n e c e s s a r y d e p e n d s o n
f a c t s o f d i s c o u r s e b e h a v i o r t h a t h a v e n o t y e t b e e n d e t e r -
m i n e d .
5 .4 TYPE3: DIGRESSIONS
T h e t h i r d t y p e o f i n t e r r u p t i o n , w h i c h w e c a l l a d i g r e s s i o n ,
i s d e f i n e d a s a s t r o n g i n t e r r u p t i o n t h a t c o n t a i n s a r e f e r -
e n c e t o s o m e e n t i t y t h a t i s s a l i e n t i n b o t h t h e i n t e r r u p t i o n
a n d th e in t e r r u p t e d s e g m e n t . F o r e x a m p l e , i f w h i l e
d i s c u ss i n g B i ll 's r o le i n c o m p a n y A B C , o n e c o n v e r s a t i o n a l
p a r t i c i p a n t i n t e r r u p t s w i t h , Speaking of Bill, that reminds
me, he came to dinner last week, B i l l r e m a i n s s a l i e n t , b u t
t h e D P c h a n g e s . D i g r e s s i o n s c o m m o n l y b e g i n w i t h
p h r a s e s s u c h a s speaking of John o r that reminds me,
a l t h o u g h n o c u e p h r a s e n e e d b e p r e s e n t , a n d that reminds
me m a y a l s o s ig n a l o t h e r s t a c k a n d i n t e n t i o n s h i ft s .
I n t h e p r o c e s s i n g o f d i g r e s s i o n s , t h e d i s c o u r s e - l e v e l
i n t e n t i o n o f t h e d i g r e s s io n f o r m s t h e b a s e o f a s e p a r a t e
i n t e n t i o n a l s t r u c t u r e , j u s t a s i n t h e c a s e o f t r u e i n t e r -
r u p t i o n s . A n e w f o c u s s p a c e i s f o r m e d a n d p u s h e d o n t o
t h e s t a c k , b u t i t c o n t a i n s a t l e a s t o n e - a n d p o s s i b l y o t h e r
- e n t i ti e s f r o m t h e i n t e r r u p t e d s e g m e n t ' s f o c u s s p a ce .
L i k e t h e f l a s h b a c k - t y p e i n t e r r u p t i o n , t h e d i g r e s s i o n m u s t
u s u a l l y b e c l o s e d w i t h a n e x p l i c i t u t t e r a n c e s u c h a s
getting back to ABC... o r anyway.
M A I N
S T A C K
F S B I L L
FS C
F S B
FS A
M A I N A U X I L I A R Y
S T A C K S T A C K
F SAB c
FS B
FS A
F SBI LL
FS c
t i m e
S T A C K A T t I S T A C K S A T t 2
F i g u r e
9 . T h e a u x i l ia r y s t a c k m o d e l f o r f l a s h b a c k s .
C o m p u t a t i o n a l
L i n g ui s ti c s, V o lu m e 1 2 , N u m b e r 3 , J u l y - S e p t e m b e r 1 9 8 6
1 9 5
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B a r b a r a J . G r o s z a n d C a n d a c e L . S i d n e r A t t e n t i o n , I n t e n t i o n s , a n d t h e S t r u c t u r e o f D i s c o u r s e
5.5 NONINTERRUPTIONS - SEMANTIC RETURNS
One case of discourse behavior that we must distinguish
comprises the so-called semantic returns observed by
Reichman (1981) and discussed by Polanyi and Scha
(1983). In all the interruptions we have considered so
far, the stack must be popped when the interruption is
over and the interrupted discourse is resumed. The focus
space for the interrupted segment is return ed to. In the
case of semantic returns, entities and DSPs that were sali-
ent during a discourse in the past are taken up once
again, but are explicitly reintroduced. For example,
suppose that yesterday two people discussed how badly
Jack was behaving at the party; then today one of them
says
R e m e m b e r o u r d i sc u s s io n a b o u t J a c k a t t h e p a r t y ?
W e l l , a l o t o f o t h e r p e o p l e t h o u g h t h e a c t e d j u s t a s b a d l y a s
w e th o u g h t h e d id . The utterances today recall, or return
to, yesterday's conversation to help satisfy the intention
that more be said about Jack's poor behavior.
Anything that can be talked about once can be talked
about again. However, if there is no focus space on the
stack corresponding to the segment and DSP being
discussed further, then, as Polanyi and Scha (1983) point
out, there is no popping of the stack. There need not be
any discourse underway when a semantic return occurs;
in such cases, the focus stack will be empty. Thus, unlike
the returns that follow normal
returns involve a push onto the
containing, among other things,
reintroduced entities.
interruptions, semantic
stack of a new space
representations of the
The separation of attentional state from intentional
structure makes clear not only what is occurring in such
cases, but also the intuitions underlying the term seman-
tic return. In reintroducing some entities fr om a previous
discourse, conversational participants are establishing
some connection between the DSP of the new segment
and the intentional structure of the original discourse. It
is not a return to a previous focus space because the
focus space for the original discourse is gone from the
stack, and the items to be referred to must be re-establ-
ished explicitly. For example, the initial refe rence to
Jack in the preceding example cannot be accomplished
with a pronoun; with no prior mention of Jack in the
current discussion, one cannot say,
R e m e m b e r o u r
d i sc u ss io n a b o u t h im a t t h e p a r t y .
The intuitive
impression of a return in the strict sense is only a return
to a previous intentional structure.
6 APPLICATION OF THE THEORY: CUE WORD S
Both attentional state and intentional structure change
during a discourse. ICPs rarely change attention by
directly and explicitly referring to attentional state (e.g.,
using the phrase
N o w l e t ' s t u r n o u r a t t e n t i o n t o . . . ) .
Like-
wise, discourses only occasionally include an explicit
reference to a change in purpose (e.g., with an utterance
such as
N o w I w a n t to e x p la i n t h e t h e o r y o f d y n a m i c
p r o g r a m m i n g ) .
More typically, ICPs employ indirect
means of indicating that a change is coming and what
kind of change it is. Cue phrases provide abbreviated,
indirect means of indicating these changes.
In all discourse changes, the ICP must provide infor-
mation that allows the OCP to determine all of the
following:
1. that a change of attention is imminent;
2. whether the change returns to a previous focus space
or creates a new one;
3. how the intention is related to other intentions;
4. what preceden ce relationships, if any, are relevant;
5. what intention is entering into focus.
Cue phrases can pack in all of this information, except
for (5). In this section, we explore the predictions of our
discourse structure theory about different uses of these
phrases and the explanations the theory offers for their
various roles.
We use the configuration of attentional state and
intentional structure illustrated in Figure 10 as the start-
ing point of our analysis. In the initial configuration, the
focus space stack has a space with DSP X at the bottom
and another space with DSP A at the top. The intentional
structure includes the information that X dominates A.
From this initial configuration, a wide variety of moves
may be made. We examine several changes and the cue
phrases that can indicate each of them. Because these
phrases and words in isolation may ambiguously play
either discourse or other functional roles, we also discuss
the other uses whenever appropriate. Furthe rmor e, cue
phrases do not function unambiguously with respect to a
particular discourse role. Thus for example,
f i r s t
can be
used for two different moves that we discuss below.
First, consider what happens when the ICP shifts to a
new DSP, B, that is dominated by A (and corresponding-
ly by X). The dominanc e relationship between A and B
becom es part of the intentional structure. In addition,
the change in DSP results in a change in the focus stack.
The focus stack models this change, which we call n e w
d o m i n a n c e , by a having new space pushed onto the stack
with B as the DSP of that space (as illustrated in Figure
11). The space cont ainin g A is salient, but less so than
the space with B. Cue phrase(s) to signal this case, and
only this one, must communicate two pieces of informa-
tion: that there is a change to som e new purpo se (result-
ing in a new focus space being created in the attentional
state model rather than a return to one on the stack) and
that the new purpose (DSP B) is dominated by DSP A.
Typical cue phrases for this kind of change are
f o r e x a m -
p l e
and
to wi t ,
and sometimes
f i r s t
and
sec o n d .
Cue phrases can also exhibit the existence of a satis-
faction- precede nce relationship. If B is to be the first in
a list of DSPs dominated by A, then words such as
f i r s t
and
i n t h e f i r s t p l a c e
can be used to communicate this
fact. Later in the discourse, cue phrases such as
sec o n d ,
th ird ,
and
f i n a l l y
can be used to indicate DSPs that are
dominat ed by A and satisfaction-prece ded by B. In these
cases, the focus space containing B would be popped
196
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B a r b a r a J. Grosz a n d C a n d a c e L. Sidner Attention, Intentions, and the Struct ure of Discourse
f r o m t h e s t a c k a n d t h e n e w f o c u s s p a c e i n s e r t e d a b o v e
t h e o n e c o n t a i n i n g A .
T h e r e a r e t h r e e o t h e r k i n d s o f d i s c o u r s e s e g m e n t s t h a t
c h a n g e t h e i n t e n t i o n a l s t r u c t u r e w i t h a r e s u l t i n g p u s h o f
n e w f o c u s s p a c e s o n t o t h e s t a c k : t h e t r u e - i n t e r r u p t i o n ,
w h e r e B i s n o t d o m i n a t e d b y A ; t h e f l a s h b a c k , w h e r e B
s a t i s f a c t i o n - p r e c e d e s A ; a n d t h e d i g r e s s i o n , w h e r e B i s
n o t d o m i n a t e d b y A , b u t s o m e e n t i t y f r o m t h e f o c u s
s p a c e c o n t a i n i n g A i s c a r r ie d o v e r t o t h e n e w f o c u s
s p a c e .
O n e w o u l d e x p e c t t h a t t h e r e m i g h t b e c u e p h r a s e s t h a t
w o u l d d i s t in g u i sh a m o n g a l l f o u r o f t h e s e k i n d s o f c h a n g -
e s . J u s t t h a t i s s o . T h e r e a r e c u e p h r a s e s t h a t a n n o u n c e
o n e a n d o n l y o n e k i n d o f c h a n g e . T h e c u e p h r a s e s
m e n t i o n e d a b o v e f o r ne w d o m i n a n c e a r e n e v e r u s e d fo r
t h e t h r e e ki n d s o f d is c o u r s e i n t e r r u p t i o n p u s h e s . T h e c u e
p h r a s e s f o r t r u e - i n t e r r u p t i o n s e x p r e s s t h e i n t e n t i o n t o
i n t e r r u p t ( e . g . E x c u s e m e a m i n u t e , o r m u s t i n t e r r u p t )
w h i l e t h e d i s t i n c t c u e p h r a s e f o r f l a s h b a c k s ( e . g . Oops,
f o r g o t a b o u t . . . ) i n d i c a t e s t h a t s o m e t h i n g i s o u t o f o r d e r .
T h e t y p i c a l o p e n i n g c u e p h r a s e s o f t h e d i g r e s s i o n
m e n t i o n t h e e n t i t y t h a t is b e i n g c a r d e d f o r w a r d ( e .g .
S p e a k i n g o f J o h n . .. o r D i d y o u h e a r a b o u t J o h n ? ).
DISCOURSE SE GMENTS
FOCUS SPACE STACK DOMINANC E HIER ARCH Y
teN,..~ 4,Uhu
dU,QI,p~iL~.
; t
/
/
\
x l
DSP = A
DSP = X
X DOMINATES A
F i g u r e 1 0. A n i n i t ia l d i s c o u r s e s t r u c t u r e c o n f i g u r a t i o n .
ATTENTIONAL~TATE CHANGE
DOMINANCE HIERARCHY
DSP = A
DSP = X
DSP = B
DSP = A
DSP = X
X DOMINATES A
A DOMINATES B
t I
t 2
F i g u re 1 1 . A t t e n t i o n a l a n d i n t e n t i o n a l s t r u c t u r e s f o r a n e w s u b s e g m e n t .
C o m p u t a t i o n a l L i n g u i st i c s , V o l u m e
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B a r b a r a J . G r o s z a n d C a n d a c e L . S i d n e r A t t e n t i o n , I n t e n t i o n s , a n d t h e S t r u c t u r e o f D i s c o u r s e
Cue phrases can also exhibit the satisfaction of a DSP,
and hence the completion of a discourse segment. The
completion of a segment causes the current space to be
popped from the stack. There are many means of
linguistically marking completions. In texts, paragraph
and chapter boundaries and explicit comments (e.g.
T h e
E n d ) are common. In conversations, completion can be
indicated either with cue phrases such as
f i n e
or
O K 1 5
or
with more explicit references to the satisfaction of the
intention (e.g.,
T h a t ' s a l l f o r p o i n t 2 ,
or
T h e a y e s h a v e i t . ) .
Most cue phrases that communicate changes to atten-
tional state announce pops of the focus stack. However ,
at least one cue phrase can be construed to indicate a
push, namely, T h a t r e m i n d s m e . By itself, this phrase does
not specify any particular change in intentional structure,
but merel y shows that ther e will be a new DSP. Since
this is equivalent to indicating that a new focus space is
to be pushed onto the stack, this cue phrase is best seen
as conveying attentional information.
Cue phrases that indicate pops to some other space
back in the stack include
b u t a n y w a y , a n y w a y , i n a n y c a s e ,
and
n o w b a c k t o . . .
When the current focus space is
popped from the stack, a space already on the stack
becomes most salient. Fro m the configuration in Figure
10, the space with A is popped from the stack, perhaps
with others, and another space on the stack becomes the
top of the stack. Popping back changes the stack without
creating a new DSP, or a dominance or satisfaction-
precedence relationship. The pop entails a return to an
old DSP; no change is effected in the intentional struc-
ture.
There are cue phrases, such as
n o w
and
n e x t ,
that
signal a change of attentional state, but do not distinguish
between the creation of a new focus space and the return
to an old one. These words can be used for either move.
For example, in a task-oriented discourse during which
some task has been mentioned but put aside to ask a
question, the use of
n o w
indicates a change of focus. The
utterance following n o w , however, will either return the
discussion to the deferred task or will introduce some
new task for consideration.
Note, finally, that a pop of the focus stack may be
achieved without the use of cue phrases as in the follow-
ing fragment of a task-oriented dialogue (Grosz 1974):
A: One bolt is stuck, i'm trying to use both the pliers and
the wrench to get it unstuck, but I haven't had much
luck.
E: Don 't use pliers. Show me what you are doing.
A: I'm pointing at the bolts.
E: Show me the 1/2 combina tion wrench, please.
A: OK.
E: Good, now show me the 1/2 box wrench.
A: I already got it loosened.
The last utterance in this fragment returns the
discourse to the discussion of the unstuck bolt. The pop
can be inferred only from the content of the main portion
of the utterance. The pronou n (or, more accurately, the
fact that it cannot be referring to the wrench) is a cue
that a pop is needed, but only the reference to the loos-
ening action allows the OCP to recognize to which
discourse segment this utterance belongs, as discussed by
Sidner (1979) and Robinson (1981). A summary of the
uses of cue phrases is given in Figure 12.
Attentional Change
(push) now, next, that reminds me, and, but
(pop to) anyway, but anyway, in any case, now back to
(complete) the end, ok, fine, (paragrap h break)
True interruption
I must interrupt, excuse me
Flashbacks
Oops, I forgot.
Digressions
By the way, incidentally, speaking of,
Did you hear about .... That r eminds me
Satisfaction-precedes
in the first place, first, second, finally, moreover,
furthermore
New dominance
for example, to wit, first, second, and, moreover,
furthermore, therefore, finally
Figure 12. The uses of cue phrases.
1 9 8 C o mp u ta t io n a l L ing u is ti c s, V o lu me 1 2 , N u m b er 3 , J u ly - S ep temb er 1 98 6
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Barbara J . Grosz and Candace L . S idner At tent ion , In tentions , and the S tructure of Discourse
T h e c a s e s l i s t e d h e r e d o n o t e x h a u s t t h e c h a n g e s i n
f o c u s s p a c e s a n d i n t h e d o m i n a n c e h i e r a r c h y t h a t c a n b e
r e p r e s e n t e d - n o r h a v e w e f u r n i s h e d a s e t o f r u l e s t h a t
s p e c i f y w h e n c u e p h r a s e s a r e n e c e s s a r y . A d d i t i o n a l
c a s e s , e s p e c i a l l y s p e c i a l s u b c a s e s o f t h e s e , m a y b e p o s s i -
b l e . W h e n d i s c o u r s e i s v i e w e d i n t e r m s o f i n t e n ti o n a l
s t r u c t u r e a n d a t t e n t i o n a l s t a t e , i t i s c l e a r e r j u s t w h a t
k i n d s o f i n f o r m a t i o n l i n g ui s ti c e x p r e s s i o n s a n d i n t o n a t i o n
c o n v e y t o th e h e a r e r a b o u t t h e d i s c o u r s e s t r uc t u r e .
F u r t h e r m o r e , i t i s c l e a r t h a t l i n g u i s t i c e x p r e s s i o n s c a n
f u n c t i o n a s c u e p h r a s e s , a s w e l l a s s e n t e n t ia l c o n n e c t i o n s ;
t h e y c a n t e l l t h e h e a r e r a b o u t c h a n g e s i n t h e d i s c o u r s e
s t r u c t u r e a n d b e c a r r i e r s o f d i s c o u r s e , r a t h e r t h a n
s e n t e n c e - l e v e l s e m a n t i c , m e a n i n g .
7 SOME PROPERTIES A N D P R O B L E M S O F
DISCOURSE-LEVEL INTENTIONS
T h e i n t e n t i o n s t h a t s e r v e a s D P / D S P s a r e n a t u r a l e x t e n -
s i o ns o f th e i n t e n t i o n s G r i c e ( 1 9 6 9 ) c o n s i d e r s e s s e n t i a l
t o d e v e l o p i n g a t h e o r y o f u t t e r e r ' s m e a n i n g . T h e r e i s a
c r u c i a l d i f f e r e n c e , h o w e v e r , b e t w e e n o u r u s e o f d i s c -
o u r s e - l e v e l i n t e n t i o n s i n th i s p a p e r ( a n d t h e t h e o r y , a s
d e v e l o p e d s o f a r ) a n d G r i c e ' s u s e o f u t t e r a n c e - l e v e l
i n t e n t i o n s . W e a r e n o t y e t a d d r e s s i n g t h e i s s u e o f
d i s c o u r s e
m e a n i n g ,
b u t a r e c o n c e r n e d w i t h t h e r o l e o f
D p / D S P s i n d e t e r m i n i n g d i s c o u r s e s t ruc ture a n d i n s p e c i -
f y i n g h o w t h e s e i n t e n t i o n s c a n b e r e c o g n i z e d b y a n O C P .
A l t h o u g h t h e i n t e n t i o n a l s t r u c t u r e o f a d i s c o u r s e p l a y s a
r o l e i n d e t e r m i n i n g d i s c o u r s e m e a n i n g , t h e D P / D S P s d o
n o t i n a n d o f t h e m s e l v e s c o n s t i t u t e d i s c o u rs e s e g m e n t
m e a n i n g . T h e c o n n e c t i o n b e t w e e n i n t e n t i o n a l s t r u c t u r e
a n d d i s c o u r s e m e a n i n g i s s i m i la r t o t h a t b e t w e e n a t t e n -
t i o n a l a n d c o g n i t i v e s t a t e s ; t h e a t t e n t i o n a l s t a t e p l a y s a
r o l e i n a h e a r e r ' s u n d e r s t a n d i n g o f w h a t t h e s p e a k e r
m e a n s b y a g i v e n s e q u e n c e o f u t t e r a n c e s i n a d i s c o u r s e
s e g m e n t , b u t i t i s n o t t h e o n l y a s p e c t o f c o g n i t i v e s t a t e
t h a t c o n t r i b u t e s t o t h i s u n d e r s t a n d i n g .
W e w i l l d r a w u p o n s o m e p a r t i c u l a r s o f G r i c e ' s d e f i -
n i t i o n o f u t t e r e r ' s m e a n i n g t o e x p l a i n D S P s m o r e f u l l y .
H i s i n i ti a l d e f i n i t i o n i s a s f o l l o w s :
U m e a n t s o m e t h i n g b y u t t e r i n g x i s t r u e i f f [ fo r
s o m e a u d i e n c e A ] :
1 . U i n t e n d e d , b y u t t e r i n g x , t o i n d u c e a c e r t a i n
r e s p o n s e i n A
2 . U i n t e n d e d A to r e c o g n i z e ,
a t l e as t i n p a r t f r o m
t he u t t e ranc e o f x , t h a t U in t e n d e d t o p r o d u c e
t h a t r e s p o n s e
3 . U i n t e n d e d t h e f u l f i l l m e n t o f t h e i n t e n t i o n
m e n t i o n e d i n ( 2 ) t o b e a t l e a s t in p a r t A ' s
r e a s o n f o r f u l f i l l i n g t h e i n t e n t i o n m e n t i o n e d i n
( 1 ) .
G r i c e r e f i n e s t h i s d e f i n i t i o n t o a d d r e s s a n u m b e r o f
c o u n t e r e x a m p l e s . T h e f o l lo w i n g p o r t i o n o f h i s f i n a l
d e f i n i t i o n 16 i s r e l e v a n t t o t h i s p a p e r :
B y u t t e r i n g x U m e a n t t h a t * 6 p is tr u e i f f
( ~ tA ) (3 f [ f e a t u r e s o f t h e u t t e r a n c e ] ) ( 3c [ w a y s o f
c o r r e l a t i n g f w i t h u t t e r a n c e s 1 7 ] ) :
( a ) U u t t e r e d x i n t e n d i n g
1 . A t o t h i n k x p o s s e s s e s f
2 . A t o t h i n k f c o r r e l a t e d i n w a y c w i t h ~ - i n g t h a t p
3 . A t o t h i n k , o n t h e b a s i s o f f u l f i ll m e n t o f ( 1 ) a n d
( 2 ) t h a t U i n t e n d s A t o t h i n k t h a t U ff s t h a t p
4 . A o n t h e b a s i s o f f u l f i l l m e n t o f ( 3 ) t o t h i n k t h a t
U ~ks th at p
5 . a n d ( i n s o m e c a s e s ) , A o n t h e b a s i s o f f u l fi l l-
m e n t o f ( 4 ) h i m s e l f t o ~ k t h a t p
G r i c e t a k e s * ~ p to b e t h e m e a n i n g o f t h e u t t e r a n c e ,
w h e r e * ff i s a m o o d i n d i c a t o r a s s o c i a t e d w i t h t h e p r o p o s i -
t i o n a l a t t i t u d e q~ ( e . g ., * q ~ = a s s e r t a n d ~ k = b e l i e v e ) . H e
c o n s i d e r s a t t i t u d e s l i k e b e l ie v i n g t h a t I C P i s a G e r m a n
s o l d ie r a n d i n t e n d i n g t o g i v e t h e I C P a b e e r a s e x a m p l e s
o f t h e k i n d s o f ~b-ing t h a t p t h a t u t t e r a n c e i n t e n t i o n s c a n
e m b e d . F o r e x p o s i t o r y p u r p o s e s , w e u s e t h e fo l l o w i n g
n o t a t i o n t o r e p r e s e n t t h e s e u t t e r a n c e - l e v e l i n t e n t i o n s :
I n t e n d ( I C P , B e l i e v e ( O C P , I C P is a G e r m a n s o l d i e r ) )
I n t e n d ( I C P , I n t e n d ( O C P , O C P g i v e I C P a b e e r ) )
T o e x t e n d G r i c e ' s d e f i n i t io n t o d i s c o u r s e s , w e r e p l a c e
t h e u t t e r a n c e x w i t h a d i s c o u r s e s e g m e n t D S , t h e u t t e r e r
U w i t h t h e i n i t i a t o r o f a d i s c o u r s e s e g m e n t I C P , a n d t h e
a u d i e n c e A w i t h t h e O C P . T o c o m p l e t e t hi s e x t e n s i o n ,
t h e f o l l o w i n g p r o b l e m s m u s t b e r e s o l v e d :
1 . s p e c i f y i n g t h e d i s c o u r s e - l e v e l in t e n t i o n s a n d a t t i t u d e s
t h a t c o r r e s p o n d t o t h e u t t e r a n c e - l e v e l i n t e n t i o n s a n d
~ ' s t ha t p ;
2 . i d e n t i f y in g t h e k i n d s o f f s t h a t c o n t r i b u t e t o d e t e r -
m i n i n g d i s c o u r s e - l e v e l i n t e n t io n s ;
3 . i d e n t i fy i n g t h e m o d e s o f c o r r e l a t i o n ( t h e c ' s ) b e t w e e n
f e a t u r e s o f t h e d i s c o u r s e s e g m e n t s a n d t y p e s o f d i s c -
o u r s e - l e v e l i n t e n t io n s ;
4 . s p e c i f y i n g h o w t h e d i s c o u r s e - l e v e l i n t e n t io n s c a n b e
r e c o g n i z e d b y a n O C P .
A l t h o u g h e a c h o f t h e s e i s s u e s i s a n u n r e s o l v e d p r o b -
l e m i n d i s c o u r s e t h e o r y , t h i s p a p e r h a s p r o v i d e d p a r t i a l
a n s w e r s . T h e e x a m p l e s p r e s e n t e d i ll u s tr a t e t h e r a n g e o f
d i s c o u r s e - l e v e l i n t e n t io n s ; t h e s e i n t e n t i o n s a p p e a r t o b e
s i m i l a r t o u t t e r a n c e - l e v e l i n t e n t i o n s i n k i n d , b u t d i f f e r i n
t h a t t h e y o c c u r i n a c o n t e x t i n w h i c h s e v e r a l u t t e r a n c e s
m a y b e re q u i r e d t o e n s u r e t h e i r c o m p r e h e n s i o n a n d s a t i s -
f a c t i o n . T h e f e a t u r e s s o f a r i d e n t i fi e d as c o n v e y i n g
i n f o r m a t i o n a b o u t D S P s a r e : s p e c i f i c li n g ui s ti c m a r k e r s
( e .g . , c u e p h r a s e s , i n t o n a t i o n ) , u t t e r a n c e - l e v e l i n t e n t i o n s ,
a n d p r o p o s i t i o n a l c o n t e n t o f t h e u t t e r a n c e s . W e h a v e n o t
e x p l o r e d t h e p r o b l e m o f i d e n t i f y i n g m o d e s o f c o r r e l a t i o n
i n a n y d e t ai l , b u t i t i s c l e a r t h a t t h o s e m o d e s t h a t o p e r a t e
a t t h e u t t e r a n c e l e v e l a l s o f u n c t i o n a t t h e d i s c o u r s e l e v e l.
A s d i s c u s s e d p r e v i o u s l y , t h e p r o p e r t r e a t m e n t o f t h e
r e c o g n i t i o n o f d i s c o u r s e - l e v e l i n t e n t i o n s i s e s p e c i a l l y
n e c e s s a r y f o r a c o m p u t a t i o n a l l y u s e f u l a c c o u n t o f
d i s c o u r se . A t t h e d i s c o u r s e l e v e l , j u s t a s a t t h e u t t e r a n c e
l e v e l , t h e i n t e n d e d r e c o g n i t i o n o f i n t e n t i o n s p l a y s a
C o m p u t a ti o n a l L i n g u is t ic s , V o l u m e 12 , N u m b e r 3 , J u l y - S e p t e m b e r 19 8 6 19 9
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B a r b a r a J . G r o s z a n d C a n d a c e L . S i d n e r A t t e n t i o n , I n t e n t i o n s , a n d t h e S t r u c t u r e o f D i s c o u r s e
c e n t r a l ro l e . T h e D S P s a r e i n t e n d e d t o b e r e c o g n i z e d :
t h e y a c h i e v e t h e i r e f f e c t s , i n p a r t , b e c a u s e t h e O C P
r e c o g n i z e s t h e I C P ' s i n t e n t i o n f o r t h e O C P t o ~ t h a t p .
T h e O C P ' s r e c o g n i t i o n o f t h i s i n t e n t i o n i s c r u c i a l t o i t s
a c h i e v i n g t h e d e s i r e d e f f e c t . I n S e c t i o n 4 w e d e s c r i b e d
c e r t a i n c o n s t r a i n t s o n t h e r e c o g n i t i o n p r o c e s s .
7.1 THE BASIC GENERALIZATION
I n e x t e n d i n g G r i c e ' s a n a l y s is t o t h e d i s c o u r s e l e v e l , w e
h a v e t o c o n s i d e r n o t o n l y i n d i v i d u a l b e l i e f s a n d
i n t e n t io n s , b u t a l s o t he r e l a t i o n s h ip s a m o n g t h e m t h a t
a r i se b e c a u s e o f th e r e l a t i o n s h i p s a m o n g v a r i o u s
d i s c o u r s e s e g m e n t s ( a n d u t t e r a n c e s w i t h i n a s e g m e n t )
a n d t h e p u r p o s e s t h e s e g m e n t s s e r v e w i t h r e s p e c t t o t h e
e n t i r e d i s c o u r s e . T o c l a r i f y t h e s e r e l a t i o n s h i p s , c o n s i d e r
a n a n a l o g o u s s i t u a t i o n w i t h n o n l i n g u i s t i c a c t i o n s . 18 A n
a c t i o n m a y d i v id e i n t o s e v e r a l s u b a c t io n s ; f o r e x a m p l e ,
t h e p l a n t i n g o f a r o s e b u s h d i v i d e s i n t o p r e p a r i n g t h e s o i l ,
d i g g i n g a h o l e , p l a c i n g t h e r o s e b u s h i n t h e h o l e , f i l l i n g
t h e r e s t o f t h e h o l e w i t h s o i l , a n d w a t e r i n g t h e g r o u n d
a r o u n d t h e b u s h . T h e i n t e n t i o n t o p e r f o r m t h e p l a n t i n g
a c t i o n i n c l ud e s s e v e r a l s u b s i d i a r y in t e n t i o n s ( o n e f o r
e a c h o f t h e s u b a c t i o n s - n a m e l y , t o d o i t) .
I n d i s c o u r s e , i n a m a n n e r t h a t i s a n a l o g o u s t o n o n l i n -
g u i s t i c a c t i o n s , t h e D P ( a n d s o m e D S P s ) i n c l u d e s s e v e r a l
s u b s i d i a r y i n t e n t i o n s r e l a t e d t o t h e D S P s i t d o m i n a t e s .
F o r p u r p o s e s o f e x p o s i t i o n , w e w i l l u s e t h e t e r m p r i m a r y
i n t en t i on
t o d i s t in g u i s h t h e o v e r a l l i n t e n t i o n o f t h e D P
f r o m t h e s u b s i d i a r y i n t e n t i o n s o f t h e D P . F o r e x a m p l e i n
t h e m o v i e s a r g u m e n t o f S e c t i o n 3 .1 , t h e p r i m a r y i n t e n -
t i o n i s f o r t h e r e a d e r t o c o m e t o b e l i e v e th a t p a r e n t s a n d
t e a c h e r s s h o u l d k e e p c h i l d r e n f r o m s e e i n g t o o m a n y
m o v i e s ; i n t h e t a s k d i a l o g u e o f S e c t i o n 3 . 2 , t h e i n t e n t i o n
i s t h a t th e a p p r e n t i c e r e m o v e t h e f l y w h e e l . S u b s i d i a r y
i n t e n t i o n s i n c l u d e , r e s p e c t i v e l y , t h e i n t e n t i o n t h a t t h e
r e a d e r b e l i e v e t h a t i t i s i m p o r t a n t t o e v a l u a t e m o v i e s a n d
t h e i n t e n t i o n t h a t t h e e x p e r t h e l p t h e a p p r e n t i c e l o c a t e
t h e s e c o n d s e t s c r e w .
B e c a u s e t h e b e l i e f s a n d i n t e n t i o n s o f a t l e a s t t w o
d i f f e r e n t p a r t i c i p a n t s a r e i n v o l v e d i n d i s c ou r s e , t w o p r o p -
e r t i e s o f t h e g e n e r a l - a c t i o n s i t u a t i o n ( a s s u m i n g a s i n g l e
a g e n t p e r f o r m s a ll a c t i o n s ) d o n o t c a r r y o v e r . F i r s t, i n a
d i s c o u r se , t h e I C P i n t e n d s t h e O C P t o r e c o g n i z e t h e I C P ' s
b e l i e f s a b o u t t h e c o n n e c t i o n s a m o n g v a r i o u s p r o p o s i t i o n s
a n d a c t i o n s . F o r e x a m p l e , i n t h e m o v i e s a r g u m e n t , t h e
r e a d e r ( O C P ) i s i n t e n d e d t o r e c o g n i z e t h a t t h e a u t h o r
( I C P ) b e l i e v e s s o m e p r o p o s i t i o n s p r o v i d e s u p p o r t f o r
o t h e r s ; i n t h e t a s k d i a l o g u e t h e e x p e r t ( I C P ) i n t e n d s t h e
a p p r e n t i c e ( O C P ) t o r e c o g n i z e t h a t t h e e x p e r t b e l i e v e s
t h e p e r f o r m a n c e o f c e r t a i n a c t i o n s c o n t r i b u t e s t o t h e
p e r f o r m a n c e o f o t h e r a c t i o n s . I n c o n t r a s t , i n t h e g e n e r -
a l - a c t i o n s i t u a t i o n i n w h i c h t h e r e i s n o c o m m u n i c a t i o n ,
t h e r e i s n o n e e d f o r r e c o g n i t i o n o f a n o t h e r a g e n t ' s b e l i e f s
a b o u t t h e i n t e r r e l a t i o n s h ip o f v a r i o u s a c t i o n s a n d
i n t e n t i o n s .
T h e s e c o n d d i f f e r e n c e c o n c e r n s t h e e x t e n t t o w h i c h
t h e s u b s i d i a r y a c t i o n s o r i n t e n t i o n s s p e c i f y th e o v e r a l l
a c t i o n o r i n t e n t io n . T o p e r f o r m s o m e a c t i o n , t h e a g e n t
m u s t p e r f o r m e a c h o f t h e s u b a c t i o n s i n v o lv e d ; b y
p e r f o r m i n g a ll o f t h e s e s u b a c t i o n s t h e a g e n t p e r f o r m s t h e
a c t i o n . I n c o n t r a s t i n a d i s c o u r s e , t h e p a r t i c i p a n t s s h a r e
t h e a s s u m p t i o n o f d i s c o u r s e s u f f i c i e n c y : i t i s a c o n v e n t i o n
o f t h e c o m m u n i c a t i v e s i t u a t i o n t h a t t h e I C P b e l i e v e s t h e
d i s c o u r s e i s s u f f i c ie n t t o a c h i e v e t h e p r i m a r y i n t e n t i o n o f
t h e D P . D i s c o u r s e s u f f i c i e n c y d o e s n o t e n t a i l l o g ic a l
s u f f i c i e n c y o r a c t i o n c o m p l e t e n e s s . I t i s n o t n e c e s s a r i l y
t h e c a s e t h a t s a t i s f a c t i o n o f a l l o f t h e D S P s i s s u f f i c i e n t i n
a n d o f i ts e l f f o r s a t i s f a c t i o n o f t h e D P . R a t h e r , t h e r e i s a n
a s s u m p t i o n t h a t t h e i n f o r m a t i o n c o n v e y e d i n t h e
d i s c o u r s e w i l l s u f f i c e i n c o n ju n c t i o n w i t h o t h e r i n f o r m a t i o n
t h e I C P b e l i e v es t h e O C P h a s ( o r c a n o b t a i n ) t o a l l o w f o r
s a t i s f a c t i o n o f t h e p r i m a r y i n t e n t i o n o f t h e D P . S a t i s f a c -
t i o n o f a l l o f t h e D S P s , i n c o n j u n c t i o n w i t h t h i s a d d i t i o n a l
i n f o r m a t i o n , is e n o u g h f o r s a t i s fa c t i o n o f t h e D P . H e n c e ,
i n d is c o u r s e t h e i n t e n t i o n a l s t r u c t u r e ( t h e a n a l o g u e o f t h e
a c t i o n h i e r a r c h y ) n e e d n o t b e c o m p l e t e .
F o r e x a m p l e , t h e p r o p o s i t i o n s e x p r e s s e d i n t h e m o v i e s
e s s a y d o n o t p r o v i d e a l o g i c a ll y s u f f i c i e n t p r o o f o f t h e
c l a i m . T h e a u t h o r f u r n i s h e s i n f o r m a t i o n h e b e l i e v e s t o b e
a d e q u a t e f o r t h e r e a d e r t o r e a c h t h e d e s i r e d c o n c l u s i o n
a n d a s s u m e s t h e r e a d e r w i l l s u p p l e m e n t w h a t i s a c t u a l l y
s a i d w i t h a p p r o p r i a t e a d d i t i o n a l i n f o r m a t i o n a n d r e a s o n -
i n g. L i k e w i s e , t h e t a s k d i a lo g u e d o e s n o t m e n t i o n a l l t h e
s u b t a s k s e x pl i ci t ly . I n s t e a d , t h e e x p e r t a n d a p p r e n t i c e
d i s c us s e x p l i c it l y o n l y t h o s e s u b t a s k s f o r w h i c h s o m e
i n s t r u c t i o n i s n e e d e d o r i n c o n n e c t i o n w i t h w h i c h s o m e
p r o b l e m a r i se s .
T o b e m o r e c o n c r e t e , w e s h a l l l o o k a t t h e e x t e n s i o n o f
t h e G r i c e a n a n a l y s i s f o r t w o p a r t i c u l a r c a s e s , o n e i n v o l v -
i n g a b e l i e f , t h e o t h e r a n i n t e n t i o n t o p e r f o r m s o m e
a c t i o n . W e s h a ll c o n s i d e r o n l y t h e s i m p l e s t s i t u a t io n s , i n
w h i c h t h e p r i m a r y in t e n ti o n s o f t h e D P / D S P s a r e a b o u t
e i t h e r b e l ie f s o r a c t i o n s , b u t n o t a m i x t u r e . A l t h o u g h t h e
t a s k d i a l o g u e o b v i o u s l y i n v o l v e s a m i x t u r e , t h i s i s a n
e x t r e m e l y c o m p l i c a t e d i s s ue t h a t d e m a n d s a d d i ti o n a l
r e s e a r c h .
7.2 THE BELIEF CASE
I n t h e b e l i e f c a s e , th e p r i m a r y i n t e n t i o n o f t h e D P i s t o
g e t t h e O C P t o b e l i e v e s o m e p r o p o s i t i o n , s a y p . E a c h o f
t h e d i s c o u r s e s e g m e n t s i s a l s o i n t e n d e d t o g e t t h e O C P t o
b e l i e v e a p r o p o s i t i o n , s a y q i f o r s o m e i = 1 . . . . n ( w h e r e
t h e r e a r e n d i sc o u r s e s e g m e n t s ) . I n a d d i t io n t o t h e p r i m a -
r y i n t e n t i o n - i . e ., t h a t t he O C P s h o u l d c o m e t o b e l i e v e p
t h e D P in c l u d e s a n i n t e n t i o n t h a t t h e O C P c o m e t o
b e l i e v e e a c h o f t h e q i a n d , i n a d d i t i o n , a n i n t e n t i o n t h a t
t h e O C P c o m e t o b e l i e v e t h e q i p r o v i d e s u p p o r t f o r p . W e
c a n r e p r e s e n t t h i s s c h e m a t i c a l l y a s : 19
Y i = 1 . . .. n I n t e n d ( I C P , B e l i e v e ( O C P , p ) A
B e l i e v e ( O C P , q i ) A
B e l i e ve ( O C P , S u p p o r t s ( p , q l A . . . A q n ) ) )
T h e r e a r e s e v e r a l t hi n g s to n o t e h e r e . T o b e g i n w i t h,
t h e f i r s t i n t e n t io n , ( I n t e n d I C P ( B e l i e v e ( O C P p ) ) , i s th e
p r i m a r y c o m p o n e n t o f t h e DS P . S e c o n d , e a c h o f t h e
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B a r b a r a J . G r o s z a n d C a n d a c e L . S i d n e r A t t e n t i o n , I n t e n t i o n s , a n d t h e S t r u c t u r e o f D i s c o u r s e
i n t e n d e d b e l i e fs in th e s e c o n d c o n j u n c t c o r r e s p o n d s t o
t h e p r i m a r y c o m p o n e n t o f t h e D S P o f s o m e e m b e d d e d
d i s c o u r se s e g m e n t . T h i r d , t h e
supports
r e l a t i o n i s n o t
i m p l i ca t i o n. T h e O C P i s n o t i n t e n d e d t o b e l i e v e t h a t t h e
q i i m p l y p , b u t r a t h e r t o b e l i e v e t h a t t h e q i i n c o n j u n c t i o n
w i t h o t h e r f a c t s a n d r u l e s t h a t t h e I C P a s s u m e s t h e O C P
h a s a v a i l a b l e o r c a n o b t a i n a n d t h u s c o m e t o b e l i e v e a r e
s u f f i c i e n t f o r t h e O C P t o c o n c l u d e p . F o u r t h , t h e
D P / D S P m a y o n l y b e c o m p l e t e l y d e t e r m i n e d a t t h e e n d
o f t h e d i s c o u r s e ( s e g m e n t ) , a s w e d i s c u s s e d i n S e c t i o n 4 .
F i n a l l y , t o d e t e r m i n e h o w t h e d i s c o u r s e s e g m e n t s
c o r r e s p o n d i n g t o t h e q i a r e r e l a t e d t o t h e o n e c o r r e -
s p o n d i n g t o p , t h e O C P o n l y h a s t o b e l i e v e t h a t t h e I C P
b e l i e v e s a s u p p o r t s r e l a t i o n s h ip h o ld s . H e n c e , f o r t h e
p u r p o s e o f r e c o g n i z i n g t h e d i s c o u r s e s t r u c t u r e , i t w o u l d
b e s u f f i c i e n t f o r t h e t h i r d c l a u s e t o b e
. . . B e l i e v e ( O C P , B e l i e v e ( I C P ,
S u p p o r ts ( p , q l A . . .A q n ) ) )
H o w e v e r , t h e D P o f a b e l i e f - c a s e d i s c o u r s e i s n o t m e r e l y
t o g e t t h e O C P t o b e l i e v e p , b u t t o g e t t h e O C P t o b e l i e v e
p b y v i r t u e o f b e l i e v i n g t h e q i . T h a t t h i s i s s o c a n b e s e e n
c l e a r l y b y c o n s i d e r i n g s i t u a t i o n s i n w h i c h t h e O C P
a l r e a d y b e l i e v e s p a n d i s k n o w n b y t h e I C P t o d o s o , b u t
d o e s n o t h a v e a g o o d r e a s o n f o r b e l i e v i n g p . T h i s l a s t
p r o p e r t y o f t h e b e l i e f c a s e i s n o t s h a r e d b y t h e a c t i o n
c a s e .
T h e r e i s a n i m p o r t a n t r e l a t i o n s h i p b e t w e e n t h e
s u p p o r t s r e l a t i o n a n d t h e d o m i n a n c e r e l a t i o n t h a t c a n
h o l d b e t w e e n D P / D S P s ; i t i s c a p t u r e d i n t h e f o l lo w i n g
r u le ( u s i n g th e s a m e n o t a t i o n a s a b o v e ) :
¥ i = 1 . . .. n I n t e n d ( C P 1, B e l i e v e ( C P 2 , p ) ) A
I n t e n d ( C P p B e l i e v e ( C P 2 , q i ) ) A
B e l i e v e ( C P p S up p o r t s( p , q l A . . . A q n ) ) ~
D O M ( I n t e n d ( C P p B e l ie v e (C P 2 ,p ) )
I n t e n d ( C P 1 , B e l i e v e ( C P 2 , q i ) ) )
T h e i m p l i c a t io n i n t he f o r w a r d d i r e c t i o n s t a t e s t h a t i f a
c o n v e r s a t i o n a l p a r t i c i p a n t ( C P I ) b e l i e v e s t h a t t h e p r o p o -
s i t i o n p i s s u p p o r t e d b y t h e p r o p o s i t i o n q i , a n d h e i n t e n d s
a n o t h e r p a r t i c i p a n t ( C P 2 ) t o a d o p t t h e s e b e l i e f s , t h e n h i s
i n t e n t i o n t h a t CP 2 b e l i e v e p d o m i n a t e s h i s i n t e n t io n t h a t
C P 2 b e l i e v e q i- V i e w e d i n t u i t iv e l y , C P l ' s b e l i e f t h a t q i
p r o v i d e s s u p p o r t f o r p , u n d e r l i e s h i s i n t e n t i o n t o g e t CP 2
t o b e l i e v e p b y g e t t i n g h i m t o b e l i e v e q i . T h e s a t i s f a c t i o n
o f C P ~ ' s i n t e n t i o n t h a t C P 2 s h o u l d b e l i e v e q i w il l h e l p
s a t i s f y C P ~ ' s i n t e n t i o n t h a t
CP 2
b e l i e v e p . T h i s r e l a t i o n -
s h i p p l a y s a r o l e i n t h e r e c o g n i t i o n o f D S P s.
7.3 THE ACTION CASE
A n a n a l o g o u s s i t u a t i o n h o l d s f o r a d i s c o u r s e s e g m e n t
c o m p r i s i n g u t t e r a n c e s i n t e n d e d t o g e t t h e O C P t o
p e r f o r m s o m e s e t o f a c t i o n s d i r e c t e d a t a c h i e v i n g s o m e
o v e r a l l t a s k ( e . g ., s o m e s e g m e n t s i n th e t a s k - o r i e n t e d
d i a l o g u e o f S e c t i o n 3 . 2 ) . T h e f u l l s p e c i f i c a t i o n o f t h e
D P / D S P c o n t a i n s a
generates
r e l a t i o n t h a t i s d e r i v e d f r o m
a r e l a t i o n d e f i n e d b y G o l d m a n ( 1 9 7 0 ) . F o r t h i s c a s e , t h e
D P / D S P s a r e o f t h e f o l l o w i n g f o r m :
¥ i = 1 . . .. n I n t e n d ( IC P , I n t e n d ( O C P , D o ( A ) ) A
I n t e n d ( O C P , D o ( a i ) ) A
B e l i e v e ( O C P , B e l i e v e ( I C P ,
G e n e r a t e s ( A , a l A . . . A a n ) ) ) )
E a c h i n t e n t i o n t o a c t r e p r e s e n t e d i n t h e s e c o n d c o n j u n c t
c o r r e s p o n d s t o t h e p r i m a r y i n t e n t i o n o f s o m e d i s c o u r s e
s e g m e n t .
L i k e s u p p o r t s , t h e g e n e r a t e s r e l a t i o n i s p a r t i a l ( i t s
p a r t i a l i t y d i s t i n g u i s h e s i t i n p a r t f r o m G o l d m a n ' s
r e l a t i o n ) . T h u s , t h e O C P i s n o t i n t e n d e d t o b e l i e v e t h a t
t h e I C P b e l i e v e s t h a t p e r f o r m a n c e o f a i a l o n e i s s u ff i c i e n t
f o r p e r f o r m a n c e o f A , b u t r a t h e r t h a t d o i n g a ll o f t h e a i
a n d o t h e r a c t i o n s t h a t t h e O C P c a n b e e x p e c t e d t o k n o w
o r fi g u r e o u t c o n s t i t u t e s a p e r f o r m a n c e o f A . I n th e t a s k
d i a l o g u e o f S e c t i o n 3 .2 , m a n y a c t i o n s t h a t a r e e s s e n t i a l t o
t h e t a s k ( e . g . , t h e a p p r e n t i c e p i c k i n g u p t h e A l l e n w r e n c h
a n d a p p l y i n g i t c o r r e c t l y t o t h e s e t s c r e w s ) a r e n e v e r e v e n
m e n t i o n e d i n t he d i a l o g u e .
N o t e t h a t i t i s u n n e c e s s a r y f o r t h e I C P o r O C P t o h a v e
a c o m p l e t e p l a n r ~ l a t i n g a l l o f t h e a i t o A a t t h e s t a r t o f
t h e d i s c o u r s e ( o r d i s c o u r s e s e g m e n t ) . A l l th a t i s r e q u i r e d
i s t h a t , f o r a n y g i v e n s e g m e n t , t h e O C P b e a b l e t o d e t e r -
m i n e w h a t i n t e n t io n t o a c t t h e s e g m e n t c o r r e s p o n d s t o
a n d w h i c h o t h e r i n t e n t i o n s d o m i n a t e t h a t i n t e n t i o n .
F i n a l ly , u n l ik e t h e b e l i e f c a s e , th e t h i r d c o n j u n c t h e r e
r e q u i r e s o n l y t h a t t h e O C P r e c o g n i z e t h a t t h e I C P
b e l i e v e s a g e n e r a t e s r e l a t i o n s h i p h o l d s . T h e O C P c a n d o
A b y v i r t u e o f d o i n g t h e a i w i t h o u t c o m i n g h i m s e l f t o
b e l i e v e a n y t h i n g a b o u t t h e r e l a ti o n s h i p s b e t w e e n A a n d
the a i .
A s i n t h e b e l i e f c a s e , t h e r e i s a n e q u i v a l e n c e t h a t l i n k s
t h e g e n e r a t e s r e l a t i o n a m o n g a c t i o n s t o t h e d o m i n a n c e
r e l a t i o n b e t w e e n i n t e n t i o n s . S c h e m a t i c a l l y , i t i s a s
f o l l o w s :
¥ i = 1 . . . . n I n t e n d ( C P 1, I n t e n d ( C P 2, D o ( A ) ) ) A
I n t e n d ( C P 1 , I n t e n d ( C P 2 , D o ( a i ) ) ) A
B e l i e v e ( C P t , G e n e r a t e s ( A , a l A . . . A a n ) ) < >
D O M ( I n t e n d (C P 1 , I n te n d (C P 2 , D o ( A ) ) )
I n t e n d ( C P t, I n t e n d ( C P 2, D o ( a i ) ) ) )
T h i s e q u i v a l e n c e s t a t e s t h a t , i f a n a g e n t ( C P 1) b e l i e v e s
t h a t t h e p e r f o r m a n c e o f s o m e a c t i o n ( a i ) c o n t r i b u t e s i n
p a r t t o t h e p e r f o r m a n c e o f a n o t h e r a c t i o n ( A ) , a n d i f C P 1
i n t e n d s f o r
CP 2 to
( i n t e n d t o ) d o b o t h o f t h e s e a c t i o n s ,
t h e n h i s i n t e n t i o n t h a t C P 2 ( i n t e n d t o ) p e r f o r m a i is
d o m i n a t e d b y h is i n te n t i o n t h a t CP 2 ( i n t e n d t o ) p e r f o r m
A . V i e w e d i n t u i t i v e l y , C P 1 ' s b e l i e f t h a t d o i n g a i w i l l
c o n t r i b u t e t o d o i n g A u n d e r l i e s h i s i n t e n t i o n t o g e t
CP 2
t o d o A b y g e t t i n g CP 2 to d o a i. T h e s a t i s f a c t i o n o f C P t ' s
i n t e n t i o n f o r C P 2 t o d o a i w i l l h e l p s a t i s f y C P ~ ' s i n t e n t i o n
f o r
CP 2 to
d o A .
S o , f o r e x a m p l e , i n t h e t a s k - o r i e n t e d d i a l o g u e o f
S e c t i o n 3 . 2 , t h e e x p e r t k n o w s t h a t u s i n g t h e w h e e l p u l l e r
i s a n e c e s s a r y p a r t o f r e m o v i n g t h e f l y w h e e l . H i s i n t e n -
t i o n t h a t t h e a p p r e n t i c e i n t e n d t o u s e t h e w h e e l p u U e r i s
t h u s d o m i n a t e d b y h i s i n t e n t i o n t h a t t h e a p p r e n t i c e
i n t e n d t o t a k e o f f t h e f l y w h e e l . S a t i s f a c t i o n o f t h e i n t e n -
t i o n t o u s e t h e w h e e l p u l l e r w i l l c o n t r i b u t e t o s a t i s f y i n g
C o m p u t a t i o n a l L i n g u i s t i c s , V o l u m e 1 2 , N u m b e r 3 , J u l y - S e p t e m b e r 1986 201
7/17/2019 Grosz & Sidner (1986)
http://slidepdf.com/reader/full/grosz-sidner-1986 28/30
Barbara J . Grusz and Candace L . S idner At tent ion , In tent ions , and the S tructure of Discourse
t h e i n t e n t i o n t o r e m o v e t h e f l y w h e e l . I n g e n e r a l , t h e
a c t i o n a i d o e s n o t h a v e t o b e a n e c e s s a r y a c t i o n t h o u g h i t
i s i n th i s e x a m p l e ( a t l e a s t i f t h e t a s k i s d o n e c o r r e c t l y ) .
A d e f i n i t i v e s t a t e m e n t c h a r a c t e r i z i n g p r i m a r y a n d
s u b s i d ia r y i n t e n t i o n s f o r t a s k - o r i e n t e d d i a l o gu e s a w a i t s
f u r t h e r r e s e a r c h n o t o n l y i n d i s c o u r s e t h e o r y , b u t a l s o i n
t h e t h e o r y o f i n t e n t i o n s a n d a c t i o n s . I n p a r t i c u l a r , a
c l e a r e r s t a t e m e n t o f th e i n t e r a c t i o n s a m o n g t h e
i n t e n t i o n s o f t h e v a r i o u s d i s c o u r s e p a r t i c i p a n t s ( w i t h
r e s p e c t t o b o t h l i n g u i s t i c a n d n o n l i n g u i s t i c a c t i o n s )
a w a i t s t h e f o r m u l a t i o n o f a b e t t e r t h e o r y o f c o o p e r a t i o n
a n d m u l t i a g e n t a c t i v i t y .
7.4 RHETORICALRELATIONS
W e a r e n o w i n a p o s i t i o n t o c o n t r a s t t h e r o l e o f
D P / D S P s , s u p p o r t s , g e n e r a t e s , D O M , a n d S P in o u r t h e o -
r y w i t h t h e r h e t o r i c a l r e l a t i o n s t h a t , a c c o r d i n g t o a
n u m b e r o f a l te r n a t i v e t h e o r ie s ( e . g. , G r i m e s 1 9 7 5 , H o b b s
1 9 79 , M a n n a n d T h o m p s o n 1 9 8 3 , R e i c h m a n - A d a r 1 9 8 4 ,
M c K e o w n 1 9 8 5 ) , a r e c la i m e d t o u n d e r l ie d i s c o u r s e s t r u c -
t u r e. A m o n g t h e v a r i ou s rh e t o r i c a l r e l a t i o n s t h a t h a v e
b e e n i n v e s t i g a t e d a r e e l a b o r a t i o n , s u m m a r i z a t i o n ,
e n a b l e m e n t , ju s t if i c a t io n , a n d c ha l l e n ge . A l t h o u g h t h e
t h e o r i e s e a c h i d e n t i f y d i f f e r e n t s p e c i f i c r e l a t i o n s , t h e y a l l
u s e s u c h r e l a t i o n s a s t h e b a s i s f o r d e t e r m i n i n g d i s c o u r s e
s t r u c t u r e .
T h e s e r h e t o r i c a l r e l a t i o n s a p p l y s p e c i f i c a l l y t o l i n g u i s -
t i c b e h a v i o r a n d m o s t o f t h e m i m p l i c i t l y i n c o r p o r a t e
i n t e n t i o ns ( e .g . , th e i n t e n t i o n t o s u m m a r i z e , t h e i n t e n t i o n
t o j u s ti f y ) . T h e i n t e n t i o n s t h a t t y p i c a ll y s e r v e a s D P / D S P s
i n o u r t h e o r y a r e m o r e b a s i c t h a n t h o s e t h a t u n d e r l i e
s u c h r h e t o r i c a l r e l a t i o n s i n t h a t t h e y a r e n o t s p e c i a l i z e d
f o r l i n g u i s t i c b e h a v i o r ; i n m a n y c a s e s , t h e i r s a t i s f a c t i o n
c a n b e r e a l i z e d b y n o n l i n g u i s t i c a c t i o n s a s w e l l a s l i n g u i s -
t i c o n es .
T h e s u p p o r t s a n d g e n e r a t e s r e l a t i o n s t h a t m u s t s o m e -
t i m e s b e i n f e r r e d t o d e t e r m i n e d o m i n a t i o n a r e a l s o m o r e
b a s i c t h a n r h e t o r i c a l r e l a t i o n s ; t h e y a r e g e n e r a l r e l a t i o n s
t h a t ho l d b e t w e e n p r o p o s i t i o n s a n d a c t io n s . H e n c e , t h e
i n f e r r i n g o f r e l a t i o n s h i p s s u c h a s s u p p o r t s a n d g e n e r a t e s
i s s i m p l e r t h a n t h a t o f r h e t o r i c a l r e l a t i o n s h i p s . T h e
d e t e r m i n a t i o n o f w h e t h e r a s u p p o r t s o r g e n e r a t e s
r e l a t i o n s h i p e x i s t s d e p e n d s o n l y o n f a c t s o f h o w t h e
w o r l d i s , n o t o n f a c t s o f t h e d i s c o u r s e . I n c o n t r a s t , t h e
r e c o g n i t i o n o f r h e t o r i c a l r e l a t i o n s r e q u i r e s t h e c o m b i n e d
u s e o f di s c o u r s e a n d d o m a i n i n f o r m a t i o n .
F o r s e v e r a l r e a s o n s , r h e t o r i c a l r e la t i o n s h i p s d o n o t
h a v e a p r i v i l e g e d s t a t u s i n t h e a c c o u n t g i v e n h e r e .
A l t h o u g h t h e y a p p e a r t o p r o v i d e a m e t a l e v e l d e s c r i p t i o n
o f t h e d i s c o u r s e , t h e i r r o l e i n d i s c o u r s e i n t e r p r e t a t i o n
r e m a i n s u n c l ea r . A s r e g a r d s d i s c o u r s e p r o c e s s i n g , i t
s e e m s o b v i o u s t h a t t h e I C P a n d O C P h a v e e s s e n t i a l l y
d i f f e r e n t a c c e s s to t h e m . I n p a r ti c u l a r , th e I C P m a y w e l l
h a v e s u c h r h e t o r ic a l r e l a t i o ns h i p s i n m i n d a s h e
p r o d u c e s u tt e r a n c e s ( a s i n M c K e o w n ' s ( 1 9 8 5 ) s y s t e m ) ,
w h e r e a s i t i s m u c h l e ss c l e a r w h e n ( i f a t a l l) t h e O C P
i n f e r s th e m . A c l a i m o f t h e t h e o r y b e i n g d e v e l o p e d i n th i s
p a p e r is t h a t a d i s c o u r s e c a n b e u n d e r s t o o d a t a b a s i c
l e v e l e v e n i f t h e O C P n e v e r d o e s o r c a n c o n s t r u c t , l e t
a l o n e n a m e , s u c h r h e t o r i c a l r e l a t io n s h i p s . F u r t h e r m o r e ,
i t a p p e a r s t h a t t h e s e r e l a t i o n s h i p s c o u l d b e r e c a s t a s a
c o m b i n a t i o n o f d o m a i n - s p e c i f i c i n f o r m a t i o n , g e n e r a l
r e l a t i o n s b e t w e e n p r o p o s i t i o n s a n d a c t i o n s ( e . g . , s u p p o r t s
a n d g e n e r a t e s ) , a n d g e n e r a l r e l a t i o n s b e t w e e n i n t e n t i o n s
( e .g . , d o m i n a t i o n a n d s a t i s f a c t i o n - p r e c e d e n c e ) . 2 0 E v e n
s o , r h e t o r i c a l r e l a t i o n s h i p s a r e , i n a ll l i k e l i h o o d , u s e f u l t o
t h e t h e o r e t i c i a n a s a n a n a l y t i c a l t o o l f o r c e r t a i n a s p e c t s
o f d i s c o u r s e a n a l y s i s .
8 CONCLUSIONS AND FUTU RE RESEARCH
T h e t h e o r y o f d i s c o u r s e s t r u c t u r e p r e s e n t e d i n t h i s p a p e r
i s a g e n e r a l i z a t i o n o f t h e o r i e s o f t a s k - o r i e n t e d d i a l o g u e s .
I t d i ff e r s f r o m p r e v i o u s g e n e r a l i z a t i o n s i n t h a t i t c a r e f u l ly
d i s t in g u i s h e s t h r e e c o m p o n e n t s o f d i s c o u r s e s t r u c t u re :
o n e l i n g u i s t i c , o n e i n t e n t i o n a l , a n d o n e a t t e n t i o n a l . T h i s
d i s t i n c t i o n p r o v i d e s a n e s s e n t i a l b a s i s f o r e x p l a i n i n g
i n t e r r u p t io n s , c u e p h r a s e s , a n d r e f e r r i n g e x p r e s s i o n s .
T h e p a r t i c u l a r i n t e n t i o n a l s t r u c t u r e u s e d a l s o d i f f e r s
f r o m t h e a n a l o g o u s a s p e c t o f p r e v i o u s g e n e r a l i z a t io n s .
A l t h o u g h , l i k e t h o s e g e n e r a l i z a t i o n s , i t s u p p l i e s t h e p r i n -
c i pa l f r a m e w o r k f o r d is c o u rs e s e g m e n t a t i o n a n d d e t e r -
m i n e s s t r u c t u r a l r e l a t i o n s h i p s f o r t h e f o c u s i n g s t r u c t u r e
( p a r t o f t h e a t t e n t i o n a l s t a t e ) , u n l i ke i t s p r e d e c e s s o r s i t
d o e s n o t d e p e n d o n t h e s p e c i a l d e t a i l s o f a n y s i n g l e
d o m a i n o r t y p e o f d i s c o u rs e .
A l t h o u g h a d m i t t e d l y s t il l i n c o m p l e t e , t h e t h e o r y d o e s
p r o v i d e a s o l i d b a s i s f o r i n v e s t i g a t i n g b o t h t h e s t r u c t u r e
a n d m e a n i n g o f d i s c o u r s e , a s w e l l a s f o r c o n s t r u c t i n g
d i s c o u r s e - p r o c e s s i n g s y s t e m s . S e v e r a l d i f f ic u l t r e s e a r c h
p r o b l e m s r e m a i n t o b e e x p l o r e d . O f t h e s e , w e t a k e t h e
f o l l o w i n g t o b e o f p r i m a r y i m p o r t a n c e :
1 . S p e c i f i c a t i o n o f t h e r e l a t i o n s h i p b e t w e e n d i s c o u r s e -
l e v e l ( D P / D S P ) a n d u t t e r a n c e - l e v e l i n t e n t i o n s ;
2 . I d e n t i f i c a t i o n o f th e i n f o r m a t i o n t h a t d i s c o u r s e p a r t i c -
i p a n t s u s e t o r e c o g n i z e t h e s e i n t e n t i o n s , a n d t h e w a y s
i n w h i c h t h e y u t i l iz e i t ;
3 D e v e l o p m e n t o f a n a d e q u a t e t r e a t m e n t o f t h e i n te r -
a c t i o n a m o n g i n t e n t i o n s o f m u l t i p l e p a r t i c ip a n t s ;
4 . I n v e s t i g a t i o n o f t h e e f f e c t o f m u l t i p le D S P s o n t h e
t h e o r y ;
5 . I n v e s t i g a t i o n o f a l t e r n a t i v e m o d e l s o f a t t e n t i o n a l
s t a t e .
F i n a l l y , t h e t h e o r y s u g g e s t s s e v e r a l i m p o r t a n t c o n j e c -
t u r e s . F i r st , t h a t a d i s c o u r s e i s c o h e r e n t o n l y w h e n i t s
d i s c o u r s e p u r p o s e i s s h a r e d b y a l l t h e p a r t i c i p a n t s a n d
w h e n e a c h u t t e r a n c e o f th e d i s c o u r se c o n t r i b u t e s t o
a c h i e v i n g t h i s p u r p o s e , e i t h e r d i r e c t l y o r i n d i r e c t l y , b y
c o n t r i b u t i n g t o t h e s a t i s f a c t i o n o f a d i s c o u r s e s e g m e n t
p u r p o s e . S e c o n d , g e n e r a l i n t u it i o n s a b o u t t o p i c c o r r e -
s p o n d m o s t c l o s e ly t o D P / D S P s , r a t h e r t h a n t o s y n t a c t i c
o r a t te n t i o n a l c o n c e p t s . F i n a l ly , t h e t h e o r y s u g g e s t s th a t
t h e s a m e i n t e n t i o n a l s t r u c t u r e c a n g i v e r i s e t o d i f f e r e n t
a t t e n t i o n a l s t ru c t u r e s t h r o u g h d i f f e r e n t d i s c o u r s e s . T h e
d i f f e r e n t a t t e n t i o n a l s t r u c t u r e s w i l l b e m a n i f e s t i n p a r t
2 0 2 C o m p u t a ti o n a l L i n g u is t ic s , V o l u m e 12 , N u m b e r 3 , J u l y - S e p t e m b e r 19 8 6
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Barbara J . Grosz and Candace L . S idner At tent ion , In tentions , and the S tructure of Discourse
b e c a u s e d i f f e r e n t r e f e r r i n g e x p r e s s i o n s w i l l b e v a l i d , a n d
i n p a r t b e c a u s e d i f f e r e n t c u e p h r a s e s a n d o t h e r i n d i c a t o r s
w i l l b e n e c e s s a r y , o p t i o n a l , o r r e d u n d a n t .
AKNOWLEDGMENTS
W e h a v e b e n e f i t e d g r e a t l y f r o m d i s c u s s i o n s w i t h M a r t h a
P o l l a c k , R a y P e r r a u l t , a n d S c o t t W e i n s t e i n . T h e p a p e r
h a s b e n e f i t e d f r o m t h e c o m m e n t s o f J o n B a r w i s e , M a r c i a
D e r r , B r a d G o o d m a n , D a v i d I s r a e l , A m i c h a i K r o n f e l d ,
M i t c h M a r c u s , M a r t h a P o l l a c k , R a y P e r r a u lt , J o h n P e r r y ,
J a n e R o b i n s o n , S t u a r t S h i e b e r , R a l p h W e i s c h e d e l , S c o t t
W e i n s t e i n , a n d t h e a n o n y m o u s r e v i e w e r s f o r
Computational L inguistics.
W h a t e v e r e r r o r s r e m a i n a r e ,
o f c o u r s e , a l l o u r s .
T h i s p a p e r w a s m a d e p o s s i b l e b y a g i f t f r o m t h e
S y s t e m D e v e l o p m e n t F o u n d a t i o n . S u p p o rt w a s a l s o
p r o v id e d f o r t h e s e c o n d a u t h o r b y t h e A d v a n c e d
R e s e a rc h P r o j e ct s A g e n c y o f t h e D e p a r tm e n t o f D e f e n s e
a n d w a s m o n i t o r e d b y O N R u n d e r C o n t r a c t N o .
N 0 0 0 1 4 - 8 5 - C - 0 0 7 9 . T h e v i e w s a n d c o n c l u s i o n s c o n t a i n e d
i n t h i s d o c u m e n t a r e t h o s e o f t h e a u t h o r s a n d s h o u l d n o t
b e i n t e r p r e t e d a s n e c e s s a r i l y r e p r e s e n t i n g t h e o f f i c i a l
p o l i c i e s , e i t h e r e x p r e s s e d o r im p l i e d , o f t h e D e f e n s e
A d v a n c e d R e s e a r c h P r o j e c t s A g e n c y o r th e U . S . G o v e r n -
m e n t .
R E F E R E N C E S
Allen, J.F. 1979 A Plan-based Approach to Speech Act Recognition.
Technical Report 131, Depart ment of Comput er Science, University
of Toronto, Toronto, Canada.
Allen, J.F. 1983 Recognizing Intentions from Natural Language Utter-
ances. In Brady, M. and Berwick, R.C., Eds., Computat ional Models
of Discourse. MIT Press: 107-166.
Allen, J.F. and Perrault, C.R. 1980 Analyzing intention in dialogues.
Arti f ic ia l In tel l igence 15(3): 143-178.
Appelt, D. 198 5 Planning English Referring Expressions. Ar t i f i c ia l
Intelligence
26: 1-33.
Butterworth, B. 1975 Hesitation and semantic planning in speech.
Journal of Psycholinguistic Research (4): 75-87.
Chafe, Wallace L. 1979 The Flow of Thought and the Flow of
Language. In Givon. T., Ed., Synt ax and Semantics , Vo l . 12 ,
Discourse and Syntax. Academic Press, New York, New York: 159-
182.
Chafe, W.L. 1980 The Deployment of Consciousness in the Production
of a Narrative. In Chafe, W.L., Ed., The Pear Stories: Cognitive,
Cultural and Ling uis t ic Aspec ts o f Narrat ive Produc t ion . Vol . 3 .
Advances in Discourse Processes.
Ablex Publishing Corp, Norwood,
New Jersey: 9-50.
Cohen, P.R. and Levesque, H.L. 1980 Speech Acts and the Recogni-
tion of Shared Plans.
Proceedings o f the Th ird Biennia l Conference o f
the Canadian Socie ty fo r Computa t iona l S tudies o f In te l l igence. Victo-
ria, British Columbia: 263-271.
Cohen, R. 1983 A Computational Model for the Analysis of Argu-
ments..Technical Report CSRG-151, Computer Systems Research
Group, University of Toronto, Toront o, Canada.
Cohen, P.R. and Levesque, H.J. 1985 Speech Acts and Rationality.
Proceedings o f 2 3rd Annua l Meeting o f the Assoc ia t ion for Computa-
tiona l Linguistics.
Chicago, Illinois: 49-60.
Firbas, J. 1971 On the Concept o f Communicat ive Dynam ism in the
Theory o f F unc t ional Sentence Perspec t ive . Brno S tudies in English,
Vol. 7.
Brno University, Brno, Czechloslovakia: 12-47.
Goldman, A.I. 1970
A Theory o f Hum an Act ion.
Princeton University
Press, Princeton, New Jersey.
Grice, H.P. 1969 Utterer 's Meaning and Intentions. Philosophical
Rev iew 68(2): 147-177.
Grimes, J.E. 1975 The
Thread of Discourse.
Mouton Press, The Hague,
Netherlands.
Grosz, Barbara [Deutsch] 1974 The Structure of Task Oriented
Dialogs. In IEEE Sym pos ium on Speech Recognit ion: Contr ibuted
Papers. Carnegie Mellon University Computer Science Dept., Pitts-
burgh, Pennsylvania: 250-253.
Grosz, B.J. 1977 The represent ation and use of focus in dialogue
understanding. Technical Report 151, Artificial Intelligence Center,
sri International, Menlo Park, California.
Grosz, B.J. 1978a Discourse Analysis. In .,Walker, D., Ed.: 235-268.
Grosz, B.J. 1978b Focus ing in Dialog. Theoret ica l Is sues in Natural
Language Processing-2. University of Illinois at Urbana-Champaign,
Champaign, Illinois: 96-103.
Grosz, B.J. 1 98 1 Focusing and Description in Natural Language
Dialogues. In Joshi, A.; Webb er, B.; and Sag, I., Eds., Elem en t s o f
Discourse Understanding. Cambridge University Press, New York,
New York: 84-105.
Grosz, B.J.; Joshi, A.K.; and Weinstein, S. 1983 Providing a Unified
Account of Definite Noun Phrases in Discourse. Proceedings o f the
21s t Annual Meeting o f the Assoc ia) ion for Computa t ional Linguis t ics .
Cambridge, Massachusetts: 44-50.
Haji~ov~i, E. 1983 Topic and Focus . Theoretical Linguistics 10(2/3):
268-276.
Hendrix, G.G. 1979 Encoding Knowledge in Partitioned Networks. In
Findler, N. V., Ed., The
Representa t ion and Use o f Knowledge in
Computers. Academic Press, New York, New York: 51-92.
Hirschberg, J. and Pierrehumbert, J. 1986 The Intonational Structuring
of Discourse.
Proceedings o f the 24 th Annual Meeting o f the Assoc i-
ation fo r Computational Linguistics. New York, New York: 136-144.
Hobbs, J. 1979 Coherenc e and Co-reference. Cognit ive Sc ience 3(1):
67-82.
Holmes, H.W. and Gallagher, O. 1917
Composition an d Rhetoric. D.
Appleto n and Co., New York, New York.
Linde, C. and Goguen, J. 1978 Structure of Planning Discourse. J.
Social BioL Struct. 1: 219-251.
Linde, C. 1979 Focus of Attent ion and the Choice of Pronouns in
Discourse. In Givon, T., Ed., Synt ax and Semantics , Vo l . 12 ,
Discourse and Syntax. Academic Press, New York, New York: 337-
354.
Litman, Diane. 1985 Plan Recognition and Discourse Analysis: An
Integrated Approach for Understan ding Dialogues. PhD disserta-
tion, University of Roche ster, Rocheste r, New York.
Mann, W.C.; Moore, M.A.; Levin, J.A.; and Carlisle, J.H. 1975
Observation Metho ds for Human Dialogue. Technical Report
RR/ 75/ 33, Information Sciences Institute, Marina del Rey, CA.
Mann, W.C. and Thompson, S.A. 1983 Relational Propositions in
Discourse. Technical Report RR-83-115, Information Sciences
Institute, Marina del Rey, CA.
Marcus, M.P.; Hindel, D.; and Fleck, M.M. 1983 D-Theory: Talking
about Talking about Trees.
Pr oc eedin gs o f t h e 2 1 s t An n u a l M ee t in g o f
the Assoc ia t ion fo r Compu ta t ional Linguist ics.
Cambridge, MA: 129-
136.
McKeown, Kathleen R. 1985 Text Generation. Cambridge University
Press, New York, New York.
Polanyi, L. and Scha, R. 1983 On the Recursive Structure of
Discourse. In Ehlich, K. and van Riemsdijk, H., Eds.,
Connectedness
in Sentence, Discourse and Text. Tilburg University, Tilburg:
141-178.
Polanyi, L. and Scha, R. 1984 A Syntactic Approach to Discourse
Semantics.
Proceedings o f In ternational Conference on C omputa t ional
Linguistics.
Stanford University, Stanford, CA: 413-419.
Polanyi, L. and Scha, R.J.H. forthcoming Discourse Syntax and
Semantics. In Polanyi, L., Ed., The S truc ture o f Discourse. Ablex
Publishing Co., Norwood, New Jersey.
Pollack, Martha E. 1986 Inferring Domain Plans in Question-An swer-
ing. PhD dissertation, University of Pennsylvania.
Reichman, R. 1981 Plain-speaking: A theory and grammar of sponta-
neous discourse. PhD dissertation, Department of Computer
Science, Harvard University. Also, BBN Report No. 4681, Bolt
Beranek and Newman Inc., Cambridge, Massachusetts.
C o m p u t a ti o n al L i n g u is t ic s , V o l u m e 12 , N u m b e r 3 , J u l y - S e p t e m b e r 19 8 6 2 0 3
7/17/2019 Grosz & Sidner (1986)
http://slidepdf.com/reader/full/grosz-sidner-1986 30/30
B a r b a r a J . G r o s z a n d C a n d a c e L . S i d n e r A t t e n t i o n , I n t e n t io n s , a n d t h e S t r u c t u r e o f D i s c o u r s e
Reichm an-Adar, R. 1984 Extende d Person-Ma chine Interface.
Ar t i f i -
c ia l In t e l l i gence 22(2): 157-218.
Reinhart, T. 1981 Pragmatics and Linguistics: An Analysis of Sentence
Topics. Phi losoph i ca 27( 1 :53-94.
Robins on, A. 1981 Determi ning Verb Phrase Referents in Dialogs.
A m e r i c a n J o u r n a l o f C o m p u t a t i o na l L i n g u is t i c s 7 ( 1 ) : 1 - 1 6 .
Schank, R.C.; Collins, G.C.; Davis, E.; Johnson, P.N.; Lytinen, S.; and
Reiser, B.J. 1982 What 's the Point? Cogn i t i ve Sc i ence 6(3):
255-275.
Sgall, P.; Haji~ov~i, E.; and Benesova, E. 1973 Top ic , F ocus and Gener -
a t i ve Seman t i c s .
Scripter Verlag, GMbH, and Co, Kronberg, Taunus,
East Germany.
Sidner, C.L. 1979 Towards a Computational Theory of Definite
Anaphora Compre hension in English Discourse. Technical Report
537, Artificial Intelligence Laboratory, Massachusetts Institute of
Technology, Cambridge, Massachusetts.
Sidner, C.L. 1982 Protocols of Users Manipulat ing Visually Present ed
Information with Natural Language. Technical Report 5128, Bolt
Beranek and Newm an Inc., Cambridge, Massachusetts.
Sidner, C.L. 1983 What the Speaker Means: The Recognition of
Speakers' Plans in Discourse. I n t e r n a t i o n a l J o u r n a l o f C o m p u t e r s a n d
M a t h e m a t i c s , Special Issue in Computational Linguistics 9(1):
71-82.
Sidner, C.L. 1985 Plan Parsing for Inten ded Respons e Recognit ion in
Discourse.
Compu ta t iona l In t e l l i gence
1(1): 1-10.
Sidner, C.L. and Israel, D.J. 1981 Recognizing Intende d Meaning and
Speaker's Plans. Proceedings of the Seventh International Joint
Conference in Artificial Intelligence. University of British Colum-
bia, British Columbia, Canada: 203-208.
Walker, D. 1978
U n d e r s ta n d i ng S p o k e n L a n g u a g e .
Elsevier North-Hol-
land, New York, New York.
Wittgenstein,L. 1953 Phi losoph i ca l Inves t iga t ions . Oxford University
Press, London, England.
NOT E S
1. The use of the phrase linguistic structure to refer to the struc-
ture of sequences of utterances is a natural extension of its use in
traditional linguistic theories to refer to the syntactic structure of
individual sentences. To avoid confusi on the phrase linguistic
structure will be used in this paper only to refer to the structure
of a sequence of utterances composing a discourse or discourse
segment.
2. Mann has also reported that the subjects did not label segments
nearly so consistently. We believe this fact is related to the kinds
of relations the labels were depen dent upon. As discussed in
Section 7.4, there is a difference between the intentional structure
we describe and the relations that others use.
3. Referring expression s can also be used to mark a discourse bound-
ary. For example, novelists sometimes use pronouns to indicate a
new scene in a story.
4. These two relations are similar to ones that play a role in parsing
at the sentence level: immedia te dominan ce and linear precedence.
However, the dominance relation, like the one in Marcus and
Hindle 's D-theor y (Marcus et al. 1983), is partial (i.e., nonimm e-
diate).
5. Even in the task case the orderings may be partial. In fact, the
systems built for task-oriented dialogues (Robinson 1981, Walker
1978) did not use a prebuilt tree, but constructe d the tree - based
on a partially-ord ered model - only as a given discourse evolved.
6. The observant reader will note that this was written in the early
days of the cinema, before the advent of sound; hence the quota-
tion marks around movies. Note also that utterance (7) contains
a somewhat odd preposition, and utterance (16) somewhat odd
definite noun phrases. We have quoted the text exactly as it was
printed.
7. The segmentation omits some levels of detail. For example, utter-
ances 19-24 are a segment within DSS. Rather than present this
detail, we concentrate on the larger segments here so as to focus
on the major issues with which this paper is concerned.
8. This modification folds in an informing action with the request.
Such combining of two t ypes of speech acts is similar to the action
subsumption that Appelt (1985) discusses in regard to referring
expressions.
9. Hirschberg and Pierrehumbert (1986) have shown recently that
intonational features, most notably pitch range, can also be used
to indicate discourse segment boundaries.
10. We assume here that the OCP must recognize intentions rather
than actions. The argument that such is the case is beyond the
scope of this paper. At a very general level, it centers on the
possibility that the very same sequence of utterance actions will
correspond to two different discourse structures with the differ-
ence statable only in terms of the ICP's intentions. The possibility
of such sequences was suggested to us by Michael Bratman
[personal communication]. The irony contained in such a clause as
you ' re a re a l swee thear t illustrates the need t o consider intentions.
11. This knowledge may be available prior to the discourse or from
information supplied by previous utterances in the discourse.
12. This bounda ry is clearly atypical of stacks. It suggests that ulti-
mately the stack model is not quite what is needed. What struc-
ture should replace the stack remains unclear to us.
13. Because this is so clearly the case on other grounds, the segment
boundary is obvious even to a reader aft er the fact.
14. From just the fragment presented, all that can be determined is
that the two dominates relationships are domination but not direct
domination.
15. O K is many ways ambiguous. It may also mean (at least) I heard
w h a t y o u s a i d , h e a r d a n d i n t e n d t o d o w h a t y o u i n t e n d m e t o in t e n d,
1 a m d o n e w h a t I u n d e r t o o k t o d o , or I a p p r o v e w h a t y o u a r e a b o u t t o
do.
16. This portion is taken from Redefinition IVB: a further redefinition
deals with abstracting about audience and would unnecessarily
complicate ou r initial view of inten tion s and discourse.
17. Grice (1969) mentions iconic, conventional, and associative
modes, giving examples of each.
18. This analogy is meant to help clarify and motivat e the discussion.
Although it also suggests some important problems in common
between research on discourse and research on theories of action
and intention, those issues are the subject of an other paper.
19. Here again we use a notational shorthand rather than a formal
language to make some of the relationships clearer.
20. This claim reflects a move analogous to the one made by Cohen
and Levesque (1985) in showing that the definitions of various
speech acts can be derived as lemmas within a general theory of
rational behavior.