Imitation in Animals Lecture 10 Psych 1090 Initially, imitation was considered a very low-level...

Imitation in Animals

Lecture 10

Psych 1090

Initially, imitation was considered a very low-level ability…

Animals’ behavior was dismissed as being unimportant because it

was “just imitation”….

At least until scientists recognized what cognitive abilities were

needed for imitation

In order to imitate, an individual must attend to the specific targeted

behavior dissect the behavior into a series of component actions

represent which body motions will re-create these actions

and integrate these actions into a coherent whole

There exist numerous different descriptions of levels of imitative

behavior

and not only of the type provided in the papers we read

Other levels exist as well…before we even get to imitation

But, before we get into any discussion of levels of behavior

involving replication,

I need to introduce some recent neurobiological studies that seem to underlie all levels

of such behavior…

issues involving MIRROR NEURONS

It has been only about a decade since the discovery of these

neurons by Rizzolatti, Fadiga, Iacoboni, and Fogassi…

They were studying area F5 in monkey brains

which roughly corresponds to the Broca’s area in humans

In humans, Broca’s area is considered to be, along w/

Wernicke’s area, the language centers…

and monkeys, of course, do not have language nor even as

complicated a vocal communication system as do

birds…

So what was going on in their F5?

As it turned out, researchers found neurons in the monkey F5 that involved hand gestures….

And, in particular, neurons that responded in identical ways when

either the monkey OR the experimenter performed the

same grasping gestures

Researchers also found that there were inhibitory neurons in the

spinal cord

that fired in opposite ways so as to inhibit the actions unless the

monkeys chose to act

Researchers called the F5 neurons MIRROR NEURONS

And did a lot of studies to show that these MNs did not fire

simply when the monkeys saw the appropriate materials or

situations

Initially, the idea was that these MNs were responsible for

imitationexcept that there was little

evidence for ‘true imitation’ in monkeys

Researchers then found that the actions that triggered the MNs in

monkeys

had to be goal-directed and in the monkeys’ repertoire already;

Novel or useless behavior patterns would not trigger the

firing

So, if you believe Thorpe’s definition of imitation

as the ‘copying of a novel or otherwise improbable act or

utterance’

then MNs weren’t really involved in imitation per se…

or at least in monkeys…

But additional studies showed comparable gestural-based MNs

in humans

and found these MNs in Broca’s area

thus revitalizing theories of gestural origins of language

something we don’t have time to discuss

Interestingly, for humans, the actions that triggered MN

responses didn’t already have to be in the repertoire

Such data suggested that different types and forms of MNs

existed

not only across species,

including levels that can be dismissed as having little or no

cognitive processing

but also to take responsibility for different types of imitative

behavior…

that is, various levels of MNs for various levels of imitation

So, let’s start by discussing these levels of behavior

patterns….

The lowest-level involves mimicry, of which there are at

least two kinds

One is structural mimicry…so-called Batesian mimicry

This mimicry is evolutionarily based….

The non-poisonous viceroy butterfly that has very similar

markings to the poisonous monarch

So that the viceroy is less likely to be eaten by animals having

experience with the monarch

The viceroy has no choice in the matter…it’s just what has

happened over time to improve its fitness

Other types of mimicry exist at the behavioral level

But are just as “mindless” as Bateson mimicry

Several different studies (e.g., Chartrand and Bargh,1999,J.

Personality & Social Psychology 76, 893-910)

have shown that when humans are deeply engaged in

conversationthey start to replicate some of each other’s actions, such as touching their hair in specific

ways

Without at all being conscious of doing so…

Think, too, of actions like yawning that are difficult to inhibit once they are viewed

These likely use the most basic levels of MNs

I believe that this level is also the one that is present in

newborns’ copying of adult tongue protrusion

Although such behavior is still presented as evidence for

neonatal imitation

Not everyone has been able to replicate the experiment

And the behavior dissipates over time

suggesting something other than true imitation

A more sophisticated level of mimicry—

Such as a juvenile’s replication of an adult’s alarm call—

likely allows for choice in whether to execute the action

(i.e., some control over the inhibitory spinal neurons)

but not in what action is expressed.

In this context, the means-goal connection is only associative …

the young animal that emits the alarm call may not have a

cognitive understanding of the exact meaning of the call

e.g., that it refers to a specific predator

but associates the call with some level of danger

and that association likely comes through the observation of the

actions that others exhibit while emitting the call

and, the structure of these calls are not learned, just their use

The next level actually involves imitation, tho’ only a low-level

formunlike the various forms of mimicry, low-level imitation

involves more than associative learning;

that is, can involve cognitive processing and some choice…

but I argue that low-level imitation has certain strictures

such as the monkeys’ need for an action to be goal-directed

and to include existent behavior patterns

And that is where we start to connect to the papers we read

One reason for studying imitation is that it involves social learning,

which separates it from things such as innately specified behavior

patterns

and brings up the issues of teaching versus learning

That issue is not discussed here because, technically, imitation can occur without any teaching

In fact, teaching suggests that the process involved requires considerable practice and emphasis on the process…

preventing spontaneous imitation

And, of course, we can’t limit imitation to live social learning

Because technically one can imitate what is heard on radio or

seen on video

though of course such issues are irrelevant in the wild…

What is important when looking for imitation in the wild is the

evidence of cultural differences

If multiple ways exist to perform a action and separate groups use

separate techniques

then learning—and likely imitation—are, by default, important issues

And although no one has looked for MNs in apes (or birds, for

that matter)

Such creatures likely have MNs and at levels that are closer to

those of humans than the MNs in monkey F5

and, enculturation may affect how these MNs develop

And what may be the difference between various MN systems is yet

a separate system

one tied more to the inhibitory neurons and that is controlled by yet a different brain structure….

And it is that structure that matures in humans but remains less mature in, e.g., monkeys

But, before we go on, we need to remember that failure to imitate

does not mean inability to imitate

Alex and Griffin saw Wart perform the string-pulling task and still

insisted on asking the human to perform the task

And boredom can also be an issue

Povinelli showed his apes how to use a rake with its tines upward and base flat so as to pull in a

piece of banana

After watching, the apes turned the rake

around

and kept trying over and over

Povinelli argued that the apes just didn’t understand imitation

and what to do….

But when you see the videotapes you see something else

The apes didn’t care at all about the silly piece of banana….

They seemed to want to explore the affordances of the

rake

and see if they could make it work in the opposite direction

just for the sake of seeing what was possible and of interest

So, deciding whether apes “ape” isn’t as simple as one would

imagine.

And much of what passes for “true” imitation might not really be that, assuming one uses Thorpe’s

definition

But having some degree of imitation is important, too

As you saw from the diagram in the Whiten article, many issues must

be addressed…

Stimulus enhancement, for example, just means that the

subject’s attention is drawn to the situation

and the subject can then devise its own solution to the problem

Such was probably the case with the tits and the milk bottles we discussed in a previous lecture

Attention was drawn to the shiny caps and maybe some drops of

cream

and then the birds’ bark-stripping behavior kicked in and a rich food

source was accessible

Similarly, locale enhancement has little to do with actual

imitation of behavior

but rather of drawing attention to an area where, for example, a rich

food source exists

that can be exploited by various techniques

We’ve talked a lot about conditioning in this course

alreadyand observational conditioning

isn’t all that different…

A subject that watches a demonstrator learn via trial-and-error tends to make fewer errors

when given the task

But the observer still makes errors

does not simply observe the final solution and immediately replicate

it

and, possibly, if it was indeed imitating, might have assumed

that all the errors were a necessary part of the procedure

Affordance learning has several possible aspects…

but basically involves learning what an object can do—possibly in

relation to another object—

in order to solve a given task and maybe even a related task

So you see that a stick can be used to poke food from

someplace…

but then you might also use the stick to determine the depth of

water

but that might not involve imitation at all

Or, in the case described in the paper, regarding a useless action

you might update your knowledge and omit something that was done

with the stick

that didn’t make any sense in terms of reaching the goal

Emulation is particularly tricky because, like affordance learning,

there may be a logical—if only to the animal subject—reason to avoid precise copying of the

technique

and to go right to the efficient way to get the goal

Which is why researchers need to be very careful of how they both design and interpret their experiments involving imitation

Including those for which the subject seems to use emulation

of either the result or the goal

The issue of goal emulation is tricky because it assumes that

the observer recognizes that the demonstrator has a goal…

that is, gets into issues of theory of mind

and, in practice, is very difficult to distinguish just from copying

results

Even using successful versus unsuccessful demonstrator may

not help…

Unless, possibly, one separates out the actions and the goals with a

separate reward

So that the goal (to get a treat) is separate from the result (to open

a box)

So, what would happen if the subject got some banana no

matter which way it opened the artificial fruit

But got chocolate only if it opened it in a particular way….

The goal would be the chocolate, separate from the result…

Of course, that would train the observer to do the task in one

way versus the other

and might defeat the whole purpose of the task itself, to see

what the subject does

but shows the difficulties involved in designing these experiments!

How do we look at very difficult tasks such as termite fishing?

Apes appear to learn by observation…

But not by direct imitation because they have to experiment

with the fine details of the task

Termite fishing obviously involves object movement

reenactment

But whether it involves real imitation is unclear

Sci Am

And how much of this also has to do with maturation of

physical dexterity?

and of the complexity of the task to be mastered?

These latter issues are particularly important for many of

the studies we read

And novelty?

As we’ve read, a standard way of testing for imitation is to use what

is known as ‘two-action tests’

that is, have a problem that can be solved in two different ways and

see which way the observer chooses

Then argue that if the observed behavior is replicated, imitation

occurs

And, of course, whether the behavior is entirely novel is also

an issue…

so, researchers attempt to test animals in various contraptions

particularly using two-action/one outcome procedures

The first issue is to find some behavior that would be novel for

the animal involved…

So, for pigeons, stepping on a treadle is probably less likely

than pecking at it…

And that can be tested by a control group of novel animals

But, obviously, stepping itself isn’t a particularly novel

behaviorAnd it isn’t clear that the birds could not simply be primed by

watching the demonstrator

tis likely the low-level imitation that we discussed earlier

So what about the marmoset paper by Huber and Voelkl?

Here the researchers determined that mouth-opening

was a rare behavior

but one that could statistically be increased by having it

demonstrated

The researchers argue that, because the animals that never

saw mouth opening basically failed the task when they couldn’t use their hands,

that use of mouth was quite novel and really was only learned via

imitation

The issue, however, was again one of priming…

How is use of a body part, albeit use in a different way than

normal,

Different from learning the affordance of a tool?

Clearly the animals that observed mouth opening learned

something

But were they truly learning to imitate?

How does one separate out these types of behavior patterns????

A paper by Huber’s group at the AISB 2007 conference did a vector analysis

of the mouth-opening

And showed that observers used very similar vectors to demonstrators where

as nonobservers did not…

A somewhat stronger argument, but not fail-safe..

Nonobservers did little that could be compared

Other work with monkeys does seem to get to this issue

By using techniques that have little to do with affordances of a

body part

But rather involve a concatenation of different

behavior patterns

Work by Fragaszy and Visalberghi is a clear example

They studied tool use in capuchin monkeys

animals that are both extremely manipulative and social

and thus good potential candidates for imitative learning

Capuchins were given an apparatus like this…

Where they actually had to learn to put the long stick into the tube

to knock out the peanut

If given enough time, all capuchins eventually learned

to do the task

But it wasn’t a simple task to put together the understanding of how to manipulate the stick to get it in

just right

and how to push it far enough…

And none of the capuchins had had experience with clear plastic

tubes that held food

or with the need to use probes to push the food out…

Would showing the monkeys what to do help them any?

Well, it helped them determine that they had to manipulate the probe in some way with respect

to the tube

but not in the exact ability to actually do the motion

And these are pretty dexterous critters

So they really did not seem to learn to imitate this complex

behavior

What about the study with marmosets that were given a more complicated task that,

similarly,

avoids affordance learning of a body part?

Here the marmosets were given the same kind of artificial fruit that required various types of

poking and turning and twisting

using the same body parts—fingers–in various different ways

to carry out novel actions on a novel apparatus

Well, the marmosets have relatively limited manipulative

capacities

So, in actuality, the animals just saw one manipulation versus

eating food from the apparatus

And although watching the demonstrator increased some

exploratory behavior

The marmosets didn’t exactly succeed on the task

And, yes, the proportion of mouth touches and hand touches reflected what the animals had

seen

But again these results suggest affordances or stimulus

enhancement and not true imitation

Overall, we find that for primates, the animals with the more advanced cognitive skills,

like the apes

succeed at what appears to be imitation whereas other primates

seem far less successful

Possibly the issue is less a matter of cognitive skills than one of MNs

Even tho’ we don’t know about MNs in apes, we can surmise

that ape MNs are likely to be more like those of humans than

those of monkeys

So, what about those keas that seemed to be pretty clever with

respect to things like insight learning?

Huber’s group now designed a task that, like the ones used for

monkeys and apes,

required a concatenation of patterns that were all novel

Not much in the wild would require this set of behavior

patterns

Interestingly, the keas in the wild, for the most part, did not

learn from watching a demonstrator

whereas keas in captivity not only solved the task on their own

but those who did not learned fairly fast from demonstrators

Quite likely, the captive birds had some experiences that were

lacking in the wild habitat

And, of course, the birds in the wild were likely not only attending

to the demonstrator

but were also attending to possible predators

So, again, many different reasons might exist why an

animal does or does not imitate…

I’ll close w/ a study on vocal imitation, which is a somewhat

different type of task

And one that some folks don’t actually include in ‘imitation’

The issue is that of vocal learning in birds is not generally

a novel, improbable act

unless one is talking about allospecific imitation

And then it is usually a bit difficult—tho’ not impossible—to argue

that allospecific song is being used

referentially

Evidence does exist, however, for birds such as song sparrows

countersinging with white-crowned sparrows using white-

crowned sparrow song

So I’m going to present related data from my parrots

Presumably learned by watching such defense

Specifically, I am going to argue that

the intentional, referential reproduction of a novel English vocalization by a Grey parrot

likely represents imitative behavior

…particularly when the targeted novel vocalization

is constructed from related elements already in the

parrot’s repertoire

Two arguments against such interpretation of Alex’s behavior:

that avian imitation of English speech does not involve intentional, accurate reproduction of human articulatory acts that nonhumans are incapable of such segmentation

Countering the first argumentCountering the first argument : :

Alex’s parrot anatomy prevents him from exactly reproducing human articulatory acts,

His ‘speech’ is not the result of, e.g., sine wave interference

but he uses his tongue, beak, glottis, and larynx in ways quite similar to that of humans

But does he have vocal segmentation?

that can be recombined in novel ways to create novel vocalizations….

Does he understand that his existent labels:

are comprised of individual units

I will argue affirmatively…

Now, little evidence exists for segmentation in animals ….

even that involving whole units to describe novel situations

The few existent incidents (e.g., monkeys’ combination of calls to

temper meaning)

are considered descriptors of the entire situation, not specific combinations to

denote one element

And, because few animals are capable of reproducing human

speech sounds….

no formal evidence exists for nonhuman segmentation of

existing labels

into phonemes to create a novel targeted vocalization

Such behaviour therefore is not only considered basic

to human language development,

but also a uniquely human trait

Even in children, however, such behavior is not innate…

from recognizing and producing words holistically (a simple form of imitation)

to recognizing words as being constructed via a rule-based phonology

Only at about three years old do they shift

Moreover, such behavior is presumed to require

development of an internal representation of phonological

structure

That is, children who demonstrate this creative behavior must:

segment the sound stream into discrete elements recognize a match between those elements and elements (or close approximations) that exist in their own repertoire

then recombine these elements in an appropriate sequence

appears to be assisted by training in sound-letter

associations…

Moreover, children’s ability to focus on the sounds of words and

sound elements of words

rather than solely on word meaning

nor are they expected to have internal representations of

phonemes

Most animals, lacking speech, are never exposed to

nor trained nor tested on

issues of sound-letter meaning, phonological awareness or phoneme

imitation…

Evidence Evidence now exists now exists for vocal for vocal

segmentatiosegmentation and n and

phonological phonological awareness awareness by a Grey by a Grey

parrot, parrot, Alex….Alex….

I will argue that:

Alex’s abilities are indeed learned

are not uniquely human

are dependent upon having considerable experience with English speech and sound-letter training.

My younger birds, lacking such training, do not engage in such

behavior

The study began when Alex was 27 years old, with 26 years of

human interaction and training

At the time, Arthur was only 3 ½ years old, with the equivalent of

about a full year of the same training

and about 2 ½ yrs of intense human interaction

We trained, Arthur, via a modeling (M/R) technique, to use “spool” to

identify a wooden bobbin….

Arthur produced it with a whistled “p”…/spul/

Arthur’s acquisition mostly followed the general pattern for birds in my lab:

He began with the vowel, /u/ (“ooo”) Added the fairly simple consonant /l/ Then, because /p/ requires esophageal speech for a parrot, he had difficulty with /sp/

But, unlike Alex and Griffin, he then used a whistled, not plosive, /p/ in /sp/

Watching Arthur, Alex began to show interest in the object

We thus began training Alex as we had Arthur

Alex, however, had also had training on phonemes:

to associate Arabic letters B, CH, I, K, N, OR, S, SH, T

with their corresponding appropriate phonological sounds (e.g., /bi/ for BI),

with plastic or wooden labels as his reward

For spool, unlike Arthur and unlike his usual form of acquisition,

/s/ (trained in conjunction with the Arabic letter, S) and wool,

to form “s” (pause) “wool” (“s-wool”; /s-pause-wUl/)

Alex began using a combination of existing phonemes and labels to

identify the object:

Alex’s /s/ (pause) /wUl/:

Note: no labels existed in Alex’s repertoire that contained /sp/,

He did not know “pull” or “pool”,

or any label that included /Ul/ or /ul/

He did know “paper”, “peach”, “parrot”, “pick”, etc ; and “shape”

and “sich” (six)So, technically, /p/ and /s/ but not /sp/

were available

Other data suggest that initial /p/ was particularly difficult….

For example, his initial attempts at the label “peach” were

“cheech” And not just for Alex;

Griffin used ‘naper’ for ‘paper’ for at least a year before producing

an appropriate initial /p/

Interestingly, Alex retained “s-wool” for almost a year….

Normally only about 20-25 modeling sessions (at most, several weeks of training)

enable learning a new label with existent phonemes

At the end of this year-long period, Alex spontaneously

produced a perfectly formed “spool” (/spul/)

Thus, he added the /p/

and also shifted the vowel toward the appropriate /u/

sound

Alex’s /spul/:

Alex’s and Arthur’s productions differ significantly in auditory and sonagraphic

patterns

Arthur:Arthur:

Alex:Alex:

Alex did not mimic Arthur

Arthur’s utterance had a avian whistle-like quality;

And closely resembled mine, even though I did less than 1/10th the

training

Alex’s utterance sounded distinctly human

Alex:Alex:

Irene:Irene:

Alex and Irene:

Alex’s /U/Alex’s /U/

Alex’s /u/Alex’s /u/

Irene’s /spu/Irene’s /spu/

Note, too, how Alex’s vowel section changed to match mine:

Other aspects of Alex’s behavior:

He differed from other occasions where he combined other parts of

labels (e.g., “banerry” from “banana” and “cherry”, or

“carrot” from “key” and “parrot”)

Those cases involved no overt practice

Without observing overt practice,

I could not claim that Alex had parsed his labels to

match a targeted utterance--

And, although he could distinguish and produce minimal pairs (e.g., “Want tea” vs. “Want

pea”),

I did not know if he had parsed these labels phonologically when

learning to produce them

suggesting he could segment phonemes from the speech

stream…..

Possibly production of “carrot” was potentiated by his already being able

to manipulate his vocal tract to produce such sounds,

or the new labels were simply created from phonotactically probable

sequences involving beginnings and ends of existent labels or,

in the case of “banerry”, from semantic relations

Other data—e.g., that he

recognizes other small phonetic recognizes other small phonetic differences (“cork” vs “corn”) as differences (“cork” vs “corn”) as meaningful, meaningful, produces initial phonemes differently produces initial phonemes differently depending upon subsequent ones (/k/ in depending upon subsequent ones (/k/ in “key” vs “cork”),“key” vs “cork”),

consistently recombines parts of labels consistently recombines parts of labels according to their order in existent labels according to their order in existent labels (i.e., combines beginnings of one label (i.e., combines beginnings of one label with the ends of otherswith the ends of others))

Merely imply but did not prove that he engages in

such top-down processing

Other behavior, e.g., producing strings such as mail chail benail in

private practice before producing the targeted, trained label nail

seemed less a deliberate attempt to create a new label from specific

sound patterns resembling the target

than deliberate play within existent patterns to hit on a correct pairing that matched some remembered

template

That is, Alex’s earlier behavior demonstrated an understanding of

the combinatory nature of his utterances,

but did not prove he understood how to segment a novel targeted

vocalization exactly,

then match its components to those in his repertoire in order

to create a trained label

Alex also demonstrated another advanced behavior, rhyme

awareness: babbling strings such as grape, grain,

chain, cane

that supports the argument that he views his labels as being constructed

from individual sound patterns

in the absence of specific objects but in the presence of his trainers….

But sound play and rhyme awareness are still somewhat

different

from behavior described for ‘spool’….

The spool data suggest that Alex, much like a child,

actually applies a phonological rule derived from knowledge of the

repertoire:

That is, recognition that sounds such as “car” and “pet”

can be recombined to identify a totally distinct object—carpet—

whose label has no referential correlation to the original

utterances.

That is, Alex appeared to form the closest

match

based on segmentation and

onset+nucleus+rhyme

Another important issue: Alex’s initial use of the space for the difficult-to-

pronounce /p/:

Children sometimes use fillers (a “holding tank”) to preserve

the number of syllables

or the prosodic rhythm of the target vocalization

until the standard form is learned

Even though Alex used a pause, not another phoneme,

his behavior suggests he understood the need for something

additional

and somewhat different to complete the vocalization

Otherwise, he would have jammed the sounds together

as he did for ‘banerry’,

to produce ‘swool’

Specifically, Alex had to:

discriminate and extract the appropriate speech sounds of the target label “spool”,

generalize these to the closest related items in his repertoire,

and additionally link the novel phonology referentially with a specific item

fit the existent sounds together—apparently including a pause to maintain spacing for an absent sound—in a particular serial order so as to add to his lexicon,

So….does this single instance indeed qualify as a case of

phonological awareness in a nonhuman?

I argue that the specificity and consistent use of the “s---wool”

combination

argues against any alternative explanation, including that of

“babble-luck” (a fortuitously correct but accidental combination)

Now, to return to the initial statement:

that Alex’s vocal segmentation provides

evidence for true imitation

rather than mimicry

‘Mere’ mimicry can be defined as the purposeless duplication of an

act

for a bird, it would be rote reproduction of human speech without referential content….

behavior that lacks cognitive complexity and intentionality

But if an act is novel, and is performed because the imitator

understands its purpose---

to reach a goal, be it an object or intentional communication, otherwise

impossible to obtain

---then the act is intentional, complex, likely indicates cognitive processing, and provides evidence

for true imitation

Alex will never attain the same language facility as a young

child…..

But his abilities question the uniqueness of some human

and nonhuman primate behavior,

including imitation

With thanks to Drs. Donald Kroodsma, Diana Reiss, and Ofer

Tchernichovski for assistance with sonagrams, and to Dr. Diane

Patterson for alerting me to the existence of “filler” phonemes

Imitation in Animals Lecture 10 Psych 1090 Initially, imitation was considered a very low-level...

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