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
Monarch Butterfly Mimics
Monarch Butterfly Mimics
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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
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:
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 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’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))
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.
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
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
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