chimpanzee “ language ” psych 1090 lecture 13. the issue of whether animals can truly...
Post on 19-Dec-2015
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TRANSCRIPT
The issue of whether animals can truly communicate with
humans is incredibly thorny….
The fights pro and con were brutal and, in a sense, doomed
the fieldHowever, before it collapsed, the work had a stunning impact not only on how we view animals,
but also on our understanding of language
And I’m going to try to give you just a taste of what happened
The work started with the Kelloggs
who brought up a chimp, Gua, along with their son, Donald….
and who showed that simple exposure to language wasn’t enough to engender it in a
nonhuman primate
Hayes and Nissen came next; they trained a chimpanzee named
Viki…Although Viki succeeded on a large
number of cognitive tasks,
she acquired only a very few English labels;
Was her failure due to her ‘primitive’ vocal tract or her
cognitive skills?
The Gardners, Allan and Trixie, watched tapes of Gua and Viki
and realized that they could understand everything without
soundi.e., that the apes used a lot of
gesturesThey reasoned that maybe one
could use ASL, the language of the deaf, to work with the apes
They reasoned that ASL would allow them to separate out issues
ofthe inability to produce labels
vocally
from the possibility of learning a human language
Note that, at the time, not everyone agreed that ASL was a
true language
Some folks looked at ASL as a proto-language;
others thought about it in terms of a rationale for a gestural
theory for the origins of human language
and others began studying ASL for the first time in great detail as
a consequence of the ape ‘language’ controversy
Were what seemed to be simple signals like “you-me-eat?”
representative of a real language, whether produced by humans or
apesor were such utterances as
primitive as they at first appeared?
Until the ape studies, no one seemed to care very much
But those issues were to come…First the Gardners started their pioneering work with Washoe
Not too long afterwards, David Premack decided to work with a
more restrictive symbol system of plastic chips…
He trained Sarah to use these chips to communicate with her trainers
And fairly soon after that, Duane Rumbaugh, working with von
Glasersfeld and others
developed a computer-based system of lexigrams that allowed
their ape, Lana
To function without any human intervention at all, to avoid cuing
And, in another lab at Columbia University, Herb Terrace started a second ASL project with Nim
Chimpsky
Terrace had been trained by Skinner and felt that language
could be taught through operant conditioning;
Nim did not learn as much as Washoe,
And Terrace’s attacks on the field pretty much brought it
down
But, again, that was in the future and an incredible amount of
information was gathered in the interim
The basic issue—how did animal “language” differ from human
language
could only be resolved if we could figure out the limits of the
animal’s abilities…
AND insure that any animal failure was not a consequence of poor training or vocal anatomy
So, that is why I’m going to start with Premack’s 1990
paper even though it’s not the oldest
Because he brings up fundamental issues of similarities and
differences Between animals’ and humans’
use of symbols…
Are they equivalently words?
Now, Premack was not the first to worry about concept “word”
In 1960, Quine wrote a paper on the topic…he proposed the
following:A linguist visits a primitive tribe, and while he is talking to a tribal member, a fuzzy creature runs
across their path
The tribal member states “Gavagai”….
Our inclination is to assume that “gavagai” is the label for that
creature in that culture
But, in reality, gavagai could mean any furry critter, anything that is running fast, a generic term for a
mammal…Or even lunch!
Or, of course, any number of different things….
The point was to make it clear that establishing the referent of a sound pattern isn’t necessarily
simple…
And that we do it by context, by exclusion, by category…etc.
Now, if we have so much confusion about what a word
is or means for humans,
there is even more confusion about what it might mean for an
apeand whether an ape would be mapping human terms onto
something already existent in ape terms
Specifically, when we train an animal to label something,
are we first having to train it to understand the concept of
labeling?
Or are we just setting up some kind of paired association that
has no linguistic function?
These are not trivial questions, and fueled the
sometimes vitriolic debates
And there aren’t any clear, clean-cut answers
Although, as we’ll see, Premack’s animals seemed to
treat their plastic chips as words…
an intriguing study by Lenneberg suggested maybe
not…Lenneberg replicated Premack’s chip study with college students,
who, not surprisingly, did extremely well on the tasks..
BUT, at the end, had no idea they had learned a ‘language’
So you need to keep this all in mind as we discuss the various papers and the various results
Remember, all of these apes were trained in very different
ways, with different techniques
And even Nim and Washoe, both taught ASL, had strikingly different
input
So let’s go back to part of Premack’s paper…about
halfway through, where he starts talking about Sarah’s
learning….After she had acquired a number
of labels, she began to learn more rapidly…
and, in fact, connected ‘words’ and objects just by having them placed
together
And, interestingly, we see this difference in our birds…
The first label is learned quickly, as a generalized ‘gimme’
The second and a few subsequent ones are learned
very slowly, Suggesting that the concept of
labeling is what is being learned
And then the animals ‘get it’…
although naming and requesting are still not separated
In fact, this separation is what caused many researchers to use nonreferential food rewards….
The animal supposedly would see the treat as a reward for naming in
general
But that didn’t happen…animals trained with nonreferential
rewards never really understood labels
They just learned associations that gave them treats without
connecting the label and the object as a name
The animals couldn’t usually transfer the label to a similar but
not identical item
So Premack could show that his animals treated the plastic chips the way children treated vocal
labels
The real question, still not totally answered, is what the chips—or
labels—represent to the ape
Let me try to clarify…
If I say “unicorn” to you,
You know exactly what I mean ….
Because you have a full mental representation of the unicorn, even if you had never seen a
picture and I said it was a “horse with a horn”
But if you needed an association between a label and a physical object in order to represent it….
You might not be able to understand what I meant…
And that’s what we can’t quite separate out for the animals
When is it just a Pavlovian association, like with a lemon and
salivating, for you and the animals…
or something more??
Does real reference require, as Premack suggests, some kind of
theory of mind?
That is, by using the label “apple”, Sarah theorizes that you have the same mental representation that
she has?
Tis not at all clear, and has been the basis for plenty of controversy
Because simple systems can be simple associations without
requiring clear representations
That is why Premack used the tests with things like apple stems, to see if these items engendered the same response as his plastic
chipsThe data suggest that the chips
may really have been representational
Another intriguing issue that Premack raises is whether
language training changes how apes think
In a sense, any training changes how thinking occurs….
That’s why programs to train students for SATs, MCATs, etc. are
so popular….
If you “teach to the test”, most students—human or nonhuman—
will do better on that test…
But they may not do so well on other types of intelligence test….
So there is a difference between practice effects and true re-training
And, again, that was one of the problems with Premack’s studies
If Sarah finally abstracts the chip that means “color of”
And learns brown through a statement “brown color of
chocolate”
The test of “brown” must be strong
But Sarah was given a brown exemplar along with three other already KNOWN color samples
So when tested on “take brown”
She might still have chosen merely on exclusion… “I know it
isn’t red, green, or yellow”…
So she would need to choose from a pile that also had purple and
silver…
And, of course, we run into the same issues of “grammar” as we
did with Herman’s dolphins….
Is it just rule-governed behavior, which isn’t exactly grammar?
So, for example, Premack’s apes did fine with their usually VERTICAL language with things
like “red over blue”
But had a terrible time with things like “red under blue”
The latter was opposite to the ordering of the chips on the
board
Such data presume rule-governed behavior, not grammar….
So, keep all this in mind when reading about the language-
trained apes that succeeded on certain tasks
And the nonlanguage-trained apes that failed…
The task with the cut-up fruits and the tubes of water is a good
example….
Nonlanguge-trained apes knew match-to-sample…
And matches were always identical….
So faced with apples and tubes of water…
It wasn’t all that surprising that they were at chance….
They had no idea that they were matching proportions….
Only identity, and nothing was an identity
The language-trained apes knew match-to-sample…
But also had lots of training where they matched objects to
chips
So they understood that the objects didn’t have to have an
exact match to be correct
To them, the partially-filled tube did not have to have the same representation as a plastic chip
What the language-trained ape knew was to derive information
from such situations
So it could respond based on the concept of ‘quarter-ness’
In a way that the nonlanguage-trained ape could not….
But language per se was not necessarily the difference
Only the way the animal had been trained to respond to
certain situations…
The same issue probably held with the causality tests…i.e.,
knife with cut item…
It wasn’t necessarily that the nonlanguage-trained apes couldn’t
understand the causality
They didn’t know how to express what they might have
known
The analogies test are my favorite
because these really ARE a lot like the kinds of tests given in
SATs
And for which training clearly makes a huge difference in
humans…
Why not in apes?
Choice of the correct alternative might be done
The trials were a bit different for the nonlanguage-trained
apes
just by matching the most number of attributes
Tis not exactly sure that I would immediately understand,
if I were an ape and not an adult human
that I should pick the matching pair
So I’m not sure that Premack’stests were entirely fair
Now, it may seem that I’m really coming down hard on Premack
And I’m not really….
I do think that his animals learned to reason in a very
advanced way
I’m just not sure they learned language
So what about an ape like Washoe,
who was not trained in an operant paradigm but rather like
a child?Well, one problem was that at
the beginning the Gardners were not fluent in sign…
So Washoe wasn’t really taught ASL
But rather a form of signed English
which was neither ASL nor English
Nevertheless, Washoe did learn a lot about the referent of each sign
A critical issue was that there were no formal drills like those of Sarah
And that Washoe had constant referential experience with all
her signs
Later, younger apes were taught by fluent ASL people
And thus these apes really were exposed to a human language
And, one of the major issues concerning this work is that ASL
does not have the same grammar as English…
So, as I noted earlier, apes that signed “you-me-eat?”
were compared to young speaking children who might say
“Mommy, lunch now?”
Or even older children who might be using full English
sentences…If, however, the apes were compared to ASL proficient
children,
The parallels were much stronger
Even repetitions used for emphasis were similar
But much argument centered on even whether Washoe’s labels
were indeed referential…
Did the ASL sign for shoe actually refer to shoes in general and not
to anything on a foot, for example?
And if the latter, was it clever metaphor or an error???
Of real import was the Gardner’s descriptions on their vocabulary tests of getting the subjects to
cooperate…
Think about trying to get a somewhat hyperactive child to sit still through a repetitive test
And you start to see their problems
Unlike the dolphins, the apes were not given their daily rations as part of the test
Mainly because hungry apes are even more difficult to get to
focus
These issues were not trivial because most critics had
worked with pigeons or rats
Or with children who were cooperative;
In most studies, ‘fussy’ children are eliminated from testing
And, overall, the apes did respond appropriately to most of the exemplars in the vocabulary
test
Interestingly, many of the errors were small errors with respect to where a sign was placed or the
action that was used…
Placing several fingers to the nose meant FLOWER and one
finger meant BUG…
In context, such errors could be made by humans and be ignored
These errors are the equivalent of mucking up small phonemes
in English
Other errors were within category… COMB for BRUSH
Objects that might be linked closely in memory
The Gardners had other data for referential sign use…
There are videos via hidden cameras of the younger chimps
correctly signing about the pictures in magazines they are
viewing
Or their asking for objects that were lost
The Gardners emphasized the strong need for interaction with
their subjects
arguing that communication is, by its very nature, interactive
and similarly emphasized the need for referential rewards
Their initial papers, published in 1969, strongly influenced some
researchers like myself and Reiss
And their work strongly contrasted with that of Terrace--
who also used sign, but in a very different manner
Terrace’s ape, Nim, would often be taught signs in the
absence of a referent
under the assumption that the referent would be distracting and
make learning more difficult
So, in many cases, only after a sign was acquired did the referent
appear
Not surprisingly, Nim didn’t understand why he was supposed
to make these signs….
and the occasional food reward just acted to confound the label to be learned with the food reward
He did eventually learn a number of signs
And initially, Terrace claimed full reference…which he later
retracted
He argued in particular that not only Nim, but all apes failed in
putting the labels into sentences
And that therefore they really hadn’t learned very much at all
Interestingly, when Terrace’s students did interact with Nim on
a less formal level
labeling actions and objects
they didn’t do it in a systematic way, so Nim was stuck with ‘gavagai’ like situations…
“Up” might be used when he was lifted to his high chair, but not when he was lifted in other circumstances
leading to lots of confusion as to the meaning of labels
The Gardners, in contrast, were very good about using a label in a number of contexts so meaning
could be abstracted
Now, as you may have noted, the Gardners take a hit at
Terrace in their article
mainly about experimental design
Because Terrace had published an article in Science a few years
earlier that had completely trashed
them
Terrace had taken some of the Gardners’ video and done a
frame-by-frame analysis
which isn’t exactly fair for a fluid language like ASL
And argued that Washoe really didn’t respond to questions but
just repeated her trainers
The arguments were unfounded, but led the
Gardners to lose funding and close their lab
Remember that ASL has a different grammar from English; sometimes where in space a sign
is placed is critical
And lots of arguments ensued
The Gardners gave their apes to their student, Roger Fouts, who had space and funding in
Oklahoma
And, as expected, continued to collaborate
Even after the apes were moved to Washington State
The Gardners were particularly interested in how the apes used
their signs interactively
because that was one of Terrace’s real arguments…hence
the 2000 report…
tho’ not clear when it was performed
As you can see from the transcripts, some of the
material was a true dialogue
Other transcripts were a bit surreal
Some of the criticisms, however, would also be leveled at young
human signers
Specifically, issues of emphasis and repetition, or motivation for a particular
itemor, in particular, interest in
something other than what the experimenter was targeting
The latter could really mess up their trials, suggesting the apes weren’t understanding the signs
Often times the apes would stick to the original topic despite the experimenter changing the subject…
That seemed particularly common when the ape was signing about food and the experimenter ignored what could have been a request
But even if the topic was not food, if the experimenter
stuck on topic
the ape was more likely to stick as well…
Sometimes expanding the utterance…but often just
copying it…
However, some of the copies were meaningful for
emphasis…
Or, when just one more sign was added, the ape was—
because it was ASL, not English—
actually requesting something of the experimenter
And one has to wonder at what the apes thought about
the non-sequitor type interactions…
Did the apes think that the humans were weirdly off-topic and should be brought around?
We can’t immediately fault the animals for their actions
Nevertheless, the apes are responding in a statistically
valid manner
IF you compare them with young signing children….
And that was really one of the major issues …
There were also ASL projects with an orangutan (Lyn Miles) and a gorilla (Penny Patterson)
but none of their data were ever published in peer-reviewed
journals
which is why we aren’t examining their material
The other major players in the ape language debate were the
Rumbaughs
As mentioned earlier, they first worked with Lana, lexigrams, and
a computer
and Lana had almost no social interaction with humans
The idea was that she could not be cued in any way by
humans
And that her data would be collected by a computer 24/7
therefore be totally above reproach
Note that she did learn to use the lexigrams in a standard
manner to request food, drinks, movies…
She even learned to “erase” a sentence given to her that
didn’t make sense….
That is, the machine could “give” food but “made”
movies….
and she’d detect the incorrect use of a verb
So Lana had really, really good production….
And, because in children, comprehension usually precedes production, Rumbaugh assumed
that Lana comprehended her labels
But that was a real mistake…
When given a lexigram and asked to choose the item to which it
referred, she was often at chance
Suggesting that she had learned particular patterns that got her
what she wanted
but only in the particular context in which it had been trained
They taught their second apes, Sherman and Austin, quite
differently in order to avoid such problems
These apes interacted more with each other than their trainers
although they were also taught with lexigrams
And the Rumbaughs stopped color coding the lexigrams as cues
Sherman and Austin did acquire a lot more reference, but in their case much of it was in context
So they understood that a “key” was something to open a box,
but had some trouble identifying it as a sole object
simply because that was the way they were trained
There are a large number of studies with these two apes
All of which are fascinating but we don’t have time to go
through them….
One issue of interest was that although the experimenters
talked with these apes,
the Rumbaugh’s claimed they didn’t understand English
Now, privately, Boysen disputed this issue, and Fouts had shown that other apes could associate
ASL signs and English
Given how many animals do understand human speech, one would expect apes to be among
them
Interestingly, data show that chinchillas and even quail
actually parse sounds just as humans….
that is, they exhibit categorical perception
Such that sounds like /p/ and /b/ have distinct cut offs in VOT and
don’t blend into one another
So, if nothing else, chimps are likely to have the hearing and
the neurological underpinnings
to be able to distinguish what we call ‘minimal pairs’
“pea/tea”, “cork/corn”
About this time, the Rumbaughs decided to try to work with a
pygmy chimp
Under the assumption that the pygmy chimps might by even
more closely related to humans
And thus more likely to acquire language-like behavior
They started with an adult, Matata, who was still caring for
her infant, Kanzi
Despite many, many months of instruction, Matata didn’t get
very far in using the lexigrams
But Kanzi, who had been watching most of his mother’s training
in a way reminiscent of our using two humans to train Alex,
Actually began to pick up quite a bit of understanding about what
the symbols meant
video
video
He even did fairly well with complicated sentences,
Even when novel and somewhat nonsensical,
whether with lexigrams or in English
Now, of course, Kanzi was far better than Sherman and
Austin
But was it because of his species or his training?
So the Rumbaughs decided to raise a pygmy chimp and a
regular one together so training wouldn’t be an issue…
Of course, the Rumbaughs could not know if there were any
individual differences in these apes….
Supposedly the apes were chosen with respect to birth-dates alone
But that doesn’t totally exclude such differences
And, of course, although they claim that the animals were
treated equivalently,
obviously every trainer knew which ape was which….
as well as the expectations of the Rumbaughs about the bonobos…
There are plenty of studies with humans suggesting that children will live up to
expectations…whether good or bad…
Substitute teachers were told that the same class was either exceptionally bright or slow…
And students met both criteria
If you look at the transcripts, both apes seem to be
functioning at similar, if not equivalent, levels
And, of course, we don’t know if what was chosen was truly
representative of the sessions
And, yes, I’m being quite critical
It’s very clear from the reported material that the apes were
treated somewhat differently;
were the caretakers truly responding to the levels of the
apes?
Differences could also be in how well the subjects attended…
And that could be a species OR an individual difference….
We really can’t know with only two subjects…
The arguments about differences in frontal lobes are compelling…
particularly with respect to keeping a string of labels in
mind…
But dolphins do just that, and an ape that makes a termite poking tool or eating certain
nettles has to have memory for various
steps
So I’m not sure that I buy into that explanation
It would be very interesting to see if the bonobos and chimps
have different MNs…
Of interest, too, is that in terms of production,
Both species of ape engaged in very non-ape like pointing and
eye contact
which suggests that avoidance of eye contact might be learned
or, obviously, at least unlearned…
And that pointing can be easily acquired in a fully enculturated
ape
And, again, the differences in production could be species-
related or not
Did the chimpanzee figure that what she had was good enough
(like my youngest parrot)…
so that it wasn’t really worth bothering to learn the additional
lexigrams?
Could be, given that she was slightly the junior
The really critical issue was that both species were given what we would call immersive input or full
enculturation
And that their development far outpaced that of Sherman and Austin who had not had such
input
or that of Lana…
Taken together, these studies suggest that whatever
communication skills apes do achieve
they, like children, need an interactive environment that
includes
reference, functionality, and socialization
So, the next question is why most of these studies have ended…
not only did the ape language work force us to examine the competencies of nonhumans
but it also forced us to examine human language more closely
Because if linguists are insisting that human language is unique
we have to understand what differentiates it from that of
nonhumans…
Not just argue that language is whatever it is that apes can’t
achieve
The bottom-line issue was that all these studies were first
attemptsAnd the glare of publicity made sure that any errors were blown
out of proportion
because many humans didn’t want to accept that an ape could
indeed communicate with humans
We now look at the work with the knowledge of all the
incredible things that animals can indeed do
And maybe wonder at the fuss…
But few of the studies we’ve read had yet been done, and animals were not considered capable of
much
So claiming language-like abilities, even if quite primitive
was more than most scientists could bear…
Just witness the current flap over the starling ‘grammar’ at present
to get an idea of what was happening in the 1970s and
1980s!
Briefly, Chomsky, Hauser and Fitch have argued that what
makes human language unique is recursion…..
being able to parse and understand embedded phrases
“This is the cat that ate the rat that lived in the house that Jack
built”
So they exposed tamarins to different types of grammars…
Some heard sets that were “ABAB” and others heard sets
that were “AABB”
Something like “put book take key” versus “put book key pail”
Note that the tamarins weren’t given anything meaningful like
verbs and nouns
Just various syllables produced either in male or female voices
And they weren’t specifically trained, just exposed to the
sounds
Then they tested whether the tamarins could detect violations
of the familiar grammars…
Those exposed to ABAB detected when they were given AABB
instead
But those exposed to AABB did not respond to ABAB as a violation
Humans, given the same nonsense syllables did catch the
differences
So the argument was that these orderings were representative of
a recursive grammar
And that a nonhuman primate failed to understand recursion,
and hence the language ‘difference’
Last week, a paper came out on starlings, who were trained to
recognize either of these grammars….
And, interestingly, the experimenters used notes from
their learned songs
“rattle” and “warble” motifs, not random syllables
They didn’t learn very quickly, but once they did
learn
It didn’t matter what they had learned; they distinguished it
from the other grammar
And easily transferred to new collections of rattles and whistles
So, did they succeed because birds need to be able to recognize vocal patterns
or because they were trained over thousand of trials and their exemplars were natural?
We won’t know til the relevant experiments are done
But that doesn’t stop the debate that this paper has
engendered in the literature
And that is not a bad thing…
Bringing up all sorts of alternative possibilities that must be examined serves to
clarify the experimental design