cosmides 1985 intro

7/29/2019 Cosmides 1985 Intro

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Deduction or Darwinian Algorithms?

An e x p l a n a t i o n of t h e " e l u s iv e " c o n t e n t e f f e c t on t h eWason se le ct io n ta sk

A t h e s i s p r es e nt ed

Leda Cosmides

The Department of Psychology and S oc ia l Re la ti on si n p a r t i a l f u l f i l l m e n t o f t h e r e qu ir em en ts

f o r t h e d e g r e e o fDoctor of Philo sophy

i n t h e s u b j e c t ofPsychology

Harvard Univers i tyCambridge, Massachusetts

Ju ly , 1985


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@ 1985 by Leda CosmidesAll r i g h t s r e se r ve d .


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A b s t r a c t

T h i s t h e s i s d e ve lo ps t h e i d e a t h a t n a t u r a l s e l e c t i o n h a s sh ap edhow humans reason about evolutionarily important domains of humana c t i v i t y . The human mind can be expect ed t o in cl ud e "Darwiniana l g o r i hmsN t h a t a r e s p e c i a l i z e d f o r p r oc e ss i ng i n ormation abouts uc h domains. Evo lut iona ry p r in c ip le s were he u r i s t i c a l l y a pp l i e dt o p inpoi n t so c i a l exchange a s an adap t ive l y impor tan t domain ofhuman activi ty ; t h e s e p r i n c i p l e s w ere a l s o a p p l i e d i n d ev el o pi n gcomp uta tio nal t h eo r i es of how humans pr oce ss inf orm ati on abouts o c i a l exchange. Evidence i s pre s e n te d s uppo r t ing the hypo the s i st h a t th e human mind inc l udes Darwinian a lgor i thms s pec ia l ize d f o rreason ing about so c i a l exchange. Th i s hypo thes is both p r ed ic tsa nd e xp la in s "c on ten t e f fe c t s n on the Wason s e le c t i on t a s k -- at e s t of l o g i c a l r e as on in g -- b e t t e r t ha n a l t e r n a t i v e t h e o ri e s .


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Table of Contents

Deduction or Darwinian Algorithms?An exp lan a t ion of t he " e lu s ive" con ten t e f f e c t

on t he Wason se le c t io n tas k

Chapter 1Log ic and t h e Stu dy of Human Reasonin g ..........hy were p sycho l og i s t s i n t e r e s t e d i n deduc t ive l og i c? . 6

What would a l o g i c module be like?..............................gDo humans hav e a l o g i c module?.................................l3

Chapter 2A r ev ie w of t h e l i t e r a t u r e on t h e " e l u s i v e " c o n t e n t e f f e c t

on t he Wason se le c t io n tas k

Introduction...................................................23The Transpor ta t ion Pr0blem.............................~.......24The Food Problem...............................................33The School Problem.............................................38S o c i a l C o n t r a c t Problems.......................................44

Chapter 3" D i f f e re n c e s i n E x pe r ie n ce " :

P ro po se d e x p l a n a t i o n s f o r t h e e l u s i v i t y of t h econ ten t e f f e c t on t h e Wason se l ec t i on t a s k

Fami l i e s o f e~planation............~...........................72Exp lanat ions p roposed i n t h e literature........................74


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D i f f e r e n t i a l A v a i l a b i l i t y.................................... 7...........................emory-cueing/Reasoning by Analogy 82Mental Models ................................................ 9Frames and Schemas........................................... 2Auxiliary Mechanisms ......................................... 5.......................................amily 2 Explanat ions 100.......................................ummary of Ex pl an at io ns 103

Chapter 4Darwinian Algorithms

Another view of human rationali ty ............................. 06A b r i e f p r im er o n n a t u r a l s e l e c t i o n ........................... 09Why should Darwinian al go ri th ms be sp ec i al iz ed and

d o m a in s p e c i f i c ?............................................ 16Chapter 5

Human S o c i a l Exchange

I n t r o d u c t i o n .................................................. 29N a tu r a l s e l e c t i o n an d s o c i a l e xc ha ng e......................... 30So c i a l exchange and th e P le i s toce ne env ironment ............... 46A computa t iona l theor y of so c i a l exchange..................... 49

Human so c i a l exchange r eq ui r es some fundame ntalc o g n i t i v e c a p a c i t i e s ...................................... 52

The grammar of s o c i a l co nt ra ct s ............................. 72Chapter 6

S o c i a l c o n t r a c t s a nd t h e Wason s e l e c t i o n t a s k : E xp er im en ts

I n t r o d u c t i o n ................................................. 196


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Experiment 1: Unfami l ia r S t anda rd Soc i a l Con t r ac t s ( L aw ) ..... 2 0 5Experiment 2 : Unfami l ia r Swi tched So c i a l Con t rac t s (Law)..... 211Experiment 3 : Unfami l ia r S tandard So c i a l Cont rac ts (Exchange). 2 1Experiment 4 : Unfami l ia r Swi tched So c i a l Con t rac ts (Exchange). 26Experiment 5: A b s t r a c t S t a nd a r d S o c i a l C o n t r a ct............... 37Experiment 6 : Fami l i a r S t anda rd So c ia l Con t r ac t s .............. 4 4

Chapter 7Discussion and Conclusions

The so c i a l con t r a c t hypo thes i s uniquely accoun t s fo r emp i r i ca lr e s u l t s on t h e Wason s e l e c t i o n t a s k ......................... 56

Are s o c i a l c o n t r a c t a l g o r i t h m s i n n a t e ? ........................259.................he r o l e of evo lu t iona ry theo ry i n p sychology 266Appendix A .................................................... 6 9Appendix B .................................................... 2 7 2Appendix C .................................................... 73Bibl iography .................................................. 7 4


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I n t r o d u c t i o n

The e qu ipo te n t i a l i t y a ss umpt ion ha s c re p t , inc ogn i to , f romth e meta-theory of behaviorism* i n t o th e meta-theory of c og ni t i vepsychology. Be ha v io r i s t s do no t e xpe ct th e l a ws of l e a r n ing t od i f f e r f rom domain t o domain1 cogn i t iv e psycholog i s ts do no texpec t the p rocess es th a t govern a t te n t io n , memory, o r reason ingt o d i f f e r from domain t o domain.

To the be ha v io r i s t , s t i m u l i a r e s t i mu l i a nd re s pons e s,re spons e s: th e i r c on te n t i s not supposed t o a f f ec t how they a r epa i red . When con ten t e f f e c t s a r e d iscovered , the beha v ior is ts pe a ks of a d ju s t i ng "parameter va lue s n , o r of d i f fe r e nc e s i n th eorgani sm's "experience" with variou s content domains . To th ec ogn i t i ve p s yc ho log i s t , i n o rma t ion i s i n ormat ion: th e con ten tof t he in format ion i s not supposed t o a f f e c t how it i s processed.When c on te n t e f f e c t s a r e d i sc ove red , the c ogn i t i ve p s yc ho log i s ta l s o s pe aks of d i f fe r e nc e s i n the o rga ni s m' s "e xper ie nc en w i t hvarious content domains .

Though unspoken, t h e message i s c lea r : Conten t i s noise .Cogni t i ve p rocesses a r e con ten t - independent , domain gene ra l ,eq ui po t en t i a l . The human mind i s a genera l purpose in format ionproc ess i ng sys tem, des igned t o process any kind of inormationwith equa l e f f i c i enc y . The fo rmat of th e in format ion -- f o rexample, whether i t i s i m a g i s t i c or p r o p o s i t i o n a l -- might make ad i f fe r e nc e i n how i t i s processed, but i t s conten t w i l l not. Theamount of exp er ie nce t h e organism ha s had wi th a domain maya f f e c t p er fo rm an ce, b ut c o r r e c t f o r t h i s and t h e e f f e c t w i l l

* f o r review, s ee Herrns te in , 1977.1


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d i s a pp e a r. T he se c l a i m s a r e r a r e l y t e s t e d ; t h e y a r e me re lyassumed.

The a l t e r n a t i v e view -- that the human mind includes anumber of domain s p ec i f i c , content-dependent , in ormat i onprocess ing sys t em s -- i s seldom e n t e r t a i n e d (Cf. Chomsky, 1975;Marr & Nis hi har a, 1978; Fodor, 1983) . Although behavior ism cameunder b r i s k a t t a c k from e vo l u t i o n a r y and e t h o l o g i c a l q u a r t e r s f o ra ss um in g t h a t l e a r n i n g was e q u i p o t e n t i a l ( H e r r n s t e i n, 1 9 7 7 ) ,co gn i t iv e psychology seems untouched by t h i s f ra y and th e s er io usproblems i t r a i s ed . Y e t t h e evo lu t ion a ry argument s aga i ns t t h eequ ipo ten t a l i t y a s sumption i n behav ior i sm apply equa l ly t ocog n i t ive psychology.

An unspoken ass ump tio n i s an unexamined assumption.C ogn i t ive p rocesses may, i n f a c t , be con ten t - independen t; i f so ,the n t h i s sho uld be proved, no t presumed. Indeed, when co nt en te f fe c t s a r e found , the con ten t -independence of c ogn i t i vep r o c e s s e s s ho u ld be a h y p o t h e s i s of l a s t r e s o r t .

C og ni ti ve pr o ce s se s , l i k e e l e c t r o n s , a r e e n t i t i e s d e fi n edso le ly by input -output r e l a t io ns . An e l ec t r on gun i s f i r e d a t ad i f f r a c t i o n s l i t , and th en i n t o a cloud chamber: even though th edata f rom t h e f i r s t f i r i n g i n d i c a t e s a wave and t h e d a t a f rom t h es ec on d i n d i c a t e s a p a r t i c l e , t h e r e a r e c om pe ll in g re a so n s f o rbe l i ev in g the se d ive rgen t p a t t e rn s were c re a te d by one and thesame ent i ty . I t would gr oss ly v io la te our most b as ic not io ns ofs i m i l a r i t y and c a u sa t i on t o c a t e g o r iz e two f i r i n g s of a n e l e c t r o ngun a s two d i f f e r en t " s t i m u l i " , j u s t because they were f i r e d a td i f f e r e n t t a r g e t s . The same i n p u t -- which was, i n t h i s case ,t h e v e ry e n t i t y p h y s i c i s t s were t r y i n g t o c h a r a c t e r i z e -- y i e l d e d

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d i f f e r e n t o u t p u ts . The o nl y r e a so n a bl e t h e o r e t i c a l a 1 e r n a t i v ewas t o complexif y t he equa t ions def in i ng th e e l ec t r on , and assumet h a t i t di d no t cor respond t o any ord inary human concept l i k e"p ar t i c l e" or "wave" (Heisenberg, 1971).

B u t t h e r e a r e no compe l li ng r ea sons -- o the r t han amisguided se ns e of parsimony -- f o r b e l i e v i n g t h a t t h e samec o g n i t i v e p r o c e s s i s i nvo lved when man i f e s t l y d i f f e r en t i np u t sy i e l d u nm is ta ka bl y d i f f e r e n t o u t pu t s . I n f a c t , b ec au se c o g n i t i v ep r o c e s s e s a r e e n t i t i e s d e f i n e d by t h e s e v e r y i n pu t -o u tp u tr e l a t i o n s , t h e d i sc o v er y of c o n te n t e f f e c t s sh ou ld be t ak e n a sprima f a c i e ev id en ce t h a t t h e d i f f e r e n t s t i m u l i t e s t e d a r ea c c e s s i n g d i f f e r e n t c o g n i t i v e p r o ce s s es . I f r e sp on se p a t t e r n sv a r y wi th s t i m u l u s co n t e n t , b u t t h e i r v a r i a t i o n d o e s n o t a pp e art o be sys tema t ic , then one should re th i nk one t s th eo ry of how t opa rs e th e world i n t o cont ent domains. Hand-waving ap pe al s t o" d i f f e r e n c e s i n ex p e ri e n ce " -- which a r e v i r t u a l l y i m p os s i bl e t of a l s i f y -- s h ou l d be e x p l an a t i o n s of l a s t r e s o r t .

When con ten t e f f e c t s a r e found, cog n i t i ve p sycho log i s t ss h ou l d e n t e r t a i n t h e h y p o t h es i s t h a t domain s p e c i f i c , c o n te n t -d ep en de nt , c o g n i t i v e p r o c e s s e s a r e r e s po n s ib l e . C on te nt e f f e c t shave been found on t h e Wason s el ec t i on t as k, a famousexper imenta l parad igm th a t t e s t s whether people reason accord ingt o th e content- independent canons of formal lo gi c . Most a t t emp tsa t e x p l a i n i n g t h e s e c o n te n t e f f e c t s h av e ap pe al ed t o " d i f f e re n c e si n su b j ec t s exper i ence" w i th va r ious con ten t doma ins. Acont rover sy has grown up a round thes e conten t e f fe c t s , because ,t o da t e , t hey have eluded p red i c t i on .

T h i s t h e s i s u se s c o n t e n t e f f e c t s on t h e Wason s e l e c t i o n t a s k3


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to t e s t th e hypothe sis th at humans have domain spe ci fi c , inna temental a lgor i thms spec ia l iz ed for reasoning about soc ia lexchange. A computat ional theory of the fun cti on al pr ope rt i es ofthese a lgor i thms was der ived us ing na t ur a l se l ec t ion theory a s ahe ur is t i c guide. C r i t i ca l te s t s were conducted t o choose betweenthe so ci al exchange hypothesis and the hypotheses i n thel i t e r a t u r e t h a t a p p ea l t o " d i f fe r e n ce s i n ex pe ri en ce ."

The disco very of sy ste ma tic va ri at io n from domain t o domaini s s t ro ng evidence t ha t domain s pe c i f i c a lgor i thms ar e a t work;so i s the discovery of sy stemati c va ria t io n wit hin a domain th a tcannot be ea s il y explai ned by a content-independent process.Both kinds of evidence ar e presented i n support of the so ci alexchange hypothesis. I argue th at no other hypothesis offe red sof a r can predi c t or expla in the exper imenta l res ul ts presentedhere in, and t h a t the s oc ia l exchange hypothesis best exp lains thecontent e f fe c ts on the Wason se le ct io n task t h a t have alreadybeen repor ted i n the l i t e r a t u r e .

The meta-th eoret ical view en ta i l ed by t h i s hypothe sis -- ofthe human mind as a co ll ec t i on of fun ctio nall y d i s t i n c t ,Chomskian "mental organsn -- also has parsimony on i t s side. Thehuman mind, l i k e t h e r e s t of th e body and i t s functions , wasdesigned by na tu ra l se le ct io n. The more important th e adap tiveproblem, the more in te ns el y se le ct io n w i l l have s pec ial ize d andimproved t h e performance of inf orm atio n proc es si ng mechanisms fo rso lv ing i t . Domain general information processing mechanismssimply cannot ins ure adaptiv e responses i n evo lut io nar i lyimp ort ant domains of human a c t i v i t y -- domains l i k e soc ia lexchange. Reasoning i n such domains should be governed by

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"Da rwin ia n a lgo r i thms n : me nta l a lgo r i thms s pe c ia l i z e d fo r s o lv ingt h e ada p t i ve prob lems t h a t d e f i ne th ese domains.

With t h i s t h e s i s , I hope t o r e s u r re c t the a rgumen ts a g a in s teq ui po te nt ia l psycholo gical mechanisms. From th e s tandpo int ofevol uti onar y t heor y, nothin g could be more unpars imonious thant h e view t h a t th e human mind i s a genera l purpose in format ionpro cess or. Yet th e ap pl ic at io n of t he Chomskian view has beenl i mi te d bec ause c o gn i t ive p s yc ho log i s t s ha ve l a c ke d a s y s te ma t ich e u r i s t i c fo r judging which domains, o th er th an language, werel i ke l y t o command fu nc t ion a l ly d i s t i n c t menta l o rgans . Becausei t i s a the ory of func t ion , na t u ra l s e le c t i on the o ry p rov ide sju s t s uc h a he u r i s t i c . Evolu t ionary p r i nc i p l e s a l low one t op inpoi n t domains fo r which n a t ur a l s e l ec t i on can be expected t ohave shap ed how humans re as on . Moreover, th ey su gg es tcomputa t ional th eo r i es (sensu Marr) of what t he i r des ign fe a t u r esa r e l i k e l y t o b e.

The theory of so c i a l exchange developed i n t h i s th e s i s wasinforme d, a t e very s t a ge , by e vo lut iona ry p r i nc ip le s . In th estu dy of human reasoni ng, th e sear ch f o r content-independentinference procedures had generated a conusion of apparent lycont rad ic t o ry re su l ts ; th e hypothes is th a t humans have domainsp ec i f i c Darwinian a lgor i thms fo r reasoning about s oc ia l exchangereso lve s much of t h i s confusion . The he ur is t i c app l i ca t io n ofevo lu t i onary theory can revo lu t io n ize co gni t i ve psychology ,a l lowing i t t o a dd re s s i s s ue s c lo s e r to the he a r t of what weth i nk of as human na ture . Th is t he s i s i s o f f e r e d a s a s ma lli l l u s t r a t i o n of i t s p o t e n t i a l .

cosmides 1985 intro

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