Gestural communication in children and chimpanzees

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Gestural communication in children and
chimpanzees
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• Humans communicate with each other in unique
  ways.
• Most obviously, linguistically, with socially
  learned, intersubjectively shared symbols
• But also gesturally. Many of the most important
  gestures humans use - e.g., for greeting or
  leaving, for threatening or insulting, for
  agreeing or disagreeing - are also socially
  learned, intersubjectively shared, symbolic
  conventions that vary across cultures in much the
  same way as linguistic symbols.
• This requires both mindreading (theory of mind)
  and the ability/motivation to cooperate with
  others.
• Tomasello (in press) Tomasello, Carpenter,
  Liszkowski (submitted)

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Outline

• Development
• Theoretical issues
• Pointing
• Pointing basics
• Infants
• Apes
• Children with autism

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Development of communication in infants
Milestone Average Age (months)
Babbling (e.g., bababa) 7
? Joint attention, anticipatory smiles by 8-9
Comprehends a word 9
Showing 9-10
Giving 12
Pointing 12
Comprehends 50 words 13
Produces first word 13 (range 9-16)
Produces 10 words 15 (range 13-19)
Produces 50 words 20 (range 14-24)
Produces word combinations 21 (range 18-24)
Adamson (1996) Carpenter, Nagell, Tomasello
(1998)
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Development of communication in infants
Milestone Average Age (months)
Babbling (e.g., bababa) 7
? Joint attention, anticipatory smiles by 8-9
Comprehends a word 9
Showing 9-10
Giving 12
Pointing 12
Comprehends 50 words 13
Produces first word 13 (range 9-16)
Produces 10 words 15 (range 13-19)
Produces 50 words 20 (range 14-24)
Produces word combinations 21 (range 18-24)
Adamson (1996) Carpenter, Nagell, Tomasello
(1998)
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Development of communication in infants
Milestone Average Age (months)
Babbling (e.g., bababa) 7
? Joint attention, anticipatory smiles by 8-9
Comprehends a word 9
Showing 9-10
Giving 12
Pointing (ToM, coop., complexity) 12
Comprehends 50 words 13
Produces first word 13 (range 9-16)
Produces 10 words 15 (range 13-19)
Produces 50 words 20 (range 14-24)
Produces word combinations 21 (range 18-24)
Adamson (1996) Carpenter, Nagell, Tomasello
(1998)
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• Theoretical debate
• Lean versus rich interpretations of gestures
  in 12-month-old infants and apes
• social-cognitive understanding
• lean just trying to achieve certain behavioral
  effects in others (see others as causal but not
  mental agents influence behavior)
• rich attempting to influence the
  intentional/mental states of others (transfer a
  mental message influence mind)
• motivation
• lean to achieve own goals (e.g., get object or
  attention from adult)
• rich also for others (inform, help, share)
  cooperative structure
• Tomasello (in press) Tomasello, Carpenter,
  Liszkowski (submitted)

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• Pointing basics
• In itself, pointing is nothing. When faced with
  a pointing finger, most animals and very young
  infants simply stare at the finger.
• Even understanding the directional nature of
  pointing is not enough to comprehend a full
  communicative act. It is possible to follow
  someones point but not know what he means by it.
  To illustrate
• Tomasello (in press) Tomasello, Carpenter,
  Liszkowski (submitted)

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Tomasello, Call, Gluckman (1997)see Call
Tomasello (2005) for a review

• In a food finding context, a human points to one
  of two opaque containers.
• Apes follow the point - but then choose
  randomly.

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• Why?
• Either apes dont know what E was directing their
  attention to (exactly what E was referring to),
  or else they dont know why E was directing them
  to it (what Es motive was).
• what precise referent is not bucket as physical
  object but bucket as location of food
• why not just to show bucket, to inform them of
  the location
• Pointing can be incomprehensible without some
  form of shared context or common ground. To
  correctly identify the referent, the recipient
  needs to assume the point is relevant to
  something she and the pointer share.
• Tomasello (in press) Tomasello, Carpenter,
  Liszkowski (submitted)

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Importance of shared context (what why)
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Importance of shared context (what why)
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• Shared context can help you determine what the
  other is pointing to (and often why)
• Expressions of attitude can also help you
  determine why.

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Attitude (observable cue to motive why?)
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Attitude (observable cue to motive why?)
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• More pointing basics
• A pointer thus combines an act of reference with
  an expression of motive, with the desire that the
  recipient attend to both of these, and from this
  infer the pointers overall intention - what the
  pointer wants the recipient to do - by finding
  some relevance to their common ground.
• involves understanding of intentions and shared
  experience
• This entire process is inherently collaborative
  communicator and recipient work together to
  identify the intended referent, as well as the
  pointers larger intention (Clark, 1996).
• Tomasello (in press) Tomasello, Carpenter,
  Liszkowski (submitted)

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• More pointing basics
• Cooperative communicative acts involve an
  additional type of intention as well a
  communicative intention or intention about the
  communication specifically (Grice, 1957 Sperber
  Wilson, 1986).
• When a person points to a tree for me, she not
  only wants me to notice the tree, she also wants
  me to notice her desire that I notice the tree.
  This additional tier is necessary to instigate in
  me the kinds of relevance inferences required to
  identify the communicator's reason for
  communicating (her motive).
• if instead she leans back and I see the tree, I
  dont need to make those kinds of inferences
• Tomasello (in press) Tomasello, Carpenter,
  Liszkowski (submitted)

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• More pointing basics
• She intends that I attend to X (and wants us to
  know this together) for some reason relevant to
  our common ground.

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• More pointing basics
• She intends that I attend to X (and wants us to
  know this together) for some reason relevant to
  our common ground.
• Apes do have some understanding of others
  intentions and attention. Either
• do not have a joint attentional frame (common
  ground) with the human that enables them to
  determine reference (Shes pointing to the
  bucket. Im searching for the grape I dont
  care about the bucket.)
• do not understand the communicative intention,
  i.e., that the human wants them to know that she
  has an intention with respect to them or
• do not understand the informing/helping motive
  (cooperative intention) of the human in this
  situation.
• Tomasello (in press) Tomasello, Carpenter,
  Liszkowski (submitted)

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Complexity of pointing
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Complexity of pointing Adult examples
Standing in line at the bank, one person points for another in the adjacent line to a scarf she has inadvertently dropped on the floor. Gloss "You dropped that."
On a river bank next to a noisy waterfall, a person hands me a book up (I am on top) for safekeeping as she climbs up. She points to the tip of a pencil protruding from the book. Gloss "Don't let this fall out".
In a bar, to a bartender, a person simply points to his empty shot glass. Gloss "I'll have another".
In airplane, I am standing up idly near the bathrooms. A man approaches and points to the bathroom door with a quizzical expression. Gloss "Are you waiting for the bathroom?"
One person to another in line, informing them of a gap in the line ahead of them. Gloss "Hey. Move up."
I approach my parked car and a truck has it blocked in. I look to the driver with an apologetic expression and point to my blocked-in car. Gloss "Sorry, but you have to move to let me out".
Tomasello, Carpenter, Liszkowski (submitted)
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Complexity of pointing Infant examples (11-13
months)
As Dad prepares to leave J points to door.
Mom pouring water J points to his glass to tell her to pour him some.
Mom tells J not to touch her hot teacup later he points to it and says "No."
Mom asks where J got something. J points out the door, saying There.
J watches as Dad arranges Christmas tree when Grandpa enters room J points to tree and says "Oh!"
J bumps his head. When Mom comes he points to offending object.
Points to sky to sound of airplane out the window (can't see).
After eating points to bathroom anticipating going to wash hands.
Mom is looking for magnet. L points to basket of fruit it is hidden in.
L pulled lamp halfway off wall. Dad comes in, L points to show what happened.
T leads Dad around house by pointing, until they find Mom.
Carpenter et al. (in preparation) Tomasello,
Carpenter, Liszkowski (submitted)
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Complexity of infant pointing

• Many motives, meanings
• important because classically infant pointing was
  thought to have only two main functions
• imperative to request objects
• declarative to share attention and interest to
  objects or events
• ape pointing apparently only imperative

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Complexity of pointing Infant examples (11-13
months)
As Dad prepares to leave J points to door.
Mom pouring water J points to his glass to tell her to pour him some.
Mom tells J not to touch her hot teacup later he points to it and says "No."
Mom asks where J got something. J points out the door, saying There.
J watches as Dad arranges Christmas tree when Grandpa enters room J points to tree and says "Oh!"
J bumps his head. When Mom comes he points to offending object.
Points to sky to sound of airplane out the window (can't see).
After eating points to bathroom anticipating going to wash hands.
Mom is looking for magnet. L points to basket of fruit it is hidden in.
L pulled lamp halfway off wall. Dad comes in, L points to show what happened.
T leads Dad around house by pointing, until they find Mom.
Carpenter et al. (in preparation) Tomasello,
Carpenter, Liszkowski (submitted)
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Complexity of infant pointing

• Many motives, meanings
• important because classically infant pointing is
  thought to have only two main functions
• imperative to request objects
• declarative to share attention and interest to
  objects or events
• ape pointing only imperative (?)
• Absent referents
• important because this is taken to be a hallmark
  of uniquely human language also evidence that it
  is communication on a mental level

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Complexity of pointing Infant examples (11-13
months)
As Dad prepares to leave J points to door.
Mom pouring water J points to his glass to tell her to pour him some.
Mom tells J not to touch her hot teacup later he points to it and says "No."
Mom asks where J got something. J points out the door, saying There.
J watches as Dad arranges Christmas tree when Grandpa enters room J points to tree and says "Oh!"
J bumps his head. When Mom comes he points to offending object.
Points to sky to sound of airplane out the window (can't see).
After eating points to bathroom anticipating going to wash hands.
Mom is looking for magnet. L points to basket of fruit it is hidden in.
L pulled lamp halfway off wall. Dad comes in, L points to show what happened.
T leads Dad around house by pointing, until they find Mom.
Carpenter et al. (in preparation) Tomasello,
Carpenter, Liszkowski (submitted)
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Complexity of infant pointing

• Many motives, meanings
• important because classically infant pointing is
  thought to have only two main functions
• imperative to request objects
• declarative to share attention and interest to
  objects or events
• ape pointing only imperative (?)
• Absent referents
• important because this is taken to be a hallmark
  of uniquely human language also evidence that it
  is communication on a mental level
• Natural observations are interesting but
  experiments are needed.

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Experiments

• Common ground
• Informative (helping) motive
• Absent referents
• Communicative intention

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Common ground

• Infants begin participating in joint attentional
  engagement by 9 months (more on that tomorrow)
• By 14 months, they can use joint attentional
  frames/common ground to interpret others points.

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Behne, Carpenter, Tomasello (2005)

• 14- to 24-month-olds
• Following a visible hiding warm-up, E hid a toy
  in one of two opaque containers.
• E indicated the toys location by pointing or
  gazing at the correct container.
• Even the youngest infants chose the correct
  container more often than chance.

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Liebal, Behne, Carpenter, Tomasello (in
preparation)

• 18-month-olds
• In each of two Common Ground conditions, infants
  participated in a different shared activity
  (cleaning up or stacking) with an adult, then
  that adult pointed (There!) at a target object.
  
• In a third, No Common Ground condition, to test
  whether infants were really using common ground,
  infants shared a frame with one adult and then a
  different adult pointed (There!).

that adult pointed
a different adult pointed
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Liebal, Behne, Carpenter, Tomasello (in
preparation)

• Even though the adults pointed in exactly the
  same way in each condition, infants interpreted
  the point differently depending on the common
  ground they shared with the adult
• In the Common Ground conditions, infants
  responses were appropriate to the previous shared
  activity.
• In the No Common Ground condition, they continued
  the previous activity less than in the
  corresponding Common Ground condition, instead
  mostly interpreting the new adults point as a
  declarative.

• Infants used their common ground with specific
  partners to interpret their partners gestures.

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Complexity of infant pointing

• Many motives, meanings
• important because classically infant pointing is
  thought to have only two main functions
• imperative to request objects
• declarative to share attention and interest to
  objects or events
• Infants do point imperatively and declaratively
  (more on this tomorrow). They also point to
  inform others of things they do not know.

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Liszkowski, Carpenter, Striano, Tomasello (2006)

• 12- and 18-month-olds
• Infants watched E repeat an action (e.g.,
  punching holes) with a target object.
• The target and a distractor object were
  displaced.
• E began looking around.
• Infants pointed to inform the adult about the
  location of the object she was looking for.

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Complexity of infant pointing

• Common ground
• Many motives, meanings, including to inform
  others.
• Absent referents
• important because this is taken to be a hallmark
  of uniquely human language also evidence that it
  is communication on a mental level

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Liszkowski, Carpenter, Tomasello (submitted)
Referent Present Phase

• 12-month-olds
• A puppet appeared E attended and emoted
  (positively or neutrally) either to it or to the
  blank screen on the other side. After the puppet
  disappeared, E turned to the infant.
• In the first phase, infants pointed more often
  when E attended to the screen than to the puppet
  (to inform).
• Infants also pointed when the referent was
  absent, differentially depending on how E had
  reacted before.

Attend Event
Attend Screen
Referent Absent Phase
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Complexity of infant pointing

• Common ground
• Many motives, meanings, including to inform
  others.
• Absent referents
• Understanding of communicative intention (tree
  example)

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Behne, Carpenter, Tomasello (2005) control
condition

• E pointed or gazed to the correct container
  but in a distracted, non-communicative manner.
• In this condition, children performed at chance
  levels.

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• Theoretical debate
• Lean versus rich interpretations of gestures
  in 12-month-old infants and apes
• social-cognitive understanding
• lean just trying to achieve certain behavioral
  effects in others (see others as causal but not
  mental agents influence behavior)
• rich attempting to influence the
  intentional/mental states of others (transfer a
  mental message influence mind)
• motivation
• lean to achieve own goals (e.g., get object or
  attention from adult)
• rich also for others (inform, help, share)
  cooperative structure
• Tomasello (in press) Tomasello, Carpenter,
  Liszkowski (submitted)

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• Infants
• Communication on mental instead of behavioral
  level ?
• Evidence (already reviewed) of understanding of
  attention and intentions by 12 months
• Absent referents (Liszkowski et al., submitted)
• Misunderstandings
• Shwe Markman (1997) when 2½-year-olds request
  something from an adult, and the adult
  misunderstands but gives them what they wanted
  anyway, they still attempt to correct the
  misunderstanding. This suggests that they had
  both the goal of getting the object and the goal
  of having the adult understand their message or
  communicative intention.
• Prosocial motivations
  ?
• to achieve own goals, of course, but also
  prosocial to inform (help), to share.

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• Apes
• Communication on mental or behavioral level
  ?
• Evidence (already reviewed) of understanding of
  perception and goals - but not attention and
  intentions (?)
• not much (if any) gesturing about absent
  referents in non-language-trained apes
• No prosocial motivations
  ?
• to achieve own goals only no evidence of
  gesturing to inform (help others, without benefit
  for themselves) or share (tomorrow).

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• Children with autism
• Communication on mental or behavioral level
  ?
• Evidence (already reviewed) of understanding of
  perception and goals - but not attention and
  intentions (?)
• ?
• No prosocial motivations
  ?
• probably to achieve own goals only no evidence
  of gesturing to share (no studies on informing).
  
• Also general difficulties with communicative
  intentions (e.g., common ground, language of the
  eyes see Sabbagh, 1999, for a review).

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Summary

• By 12 months, when they first begin pointing,
  infants already show the basics of uniquely human
  communication, supporting the rich view.
• Support for the social-pragmatic view of language
  acquisition (Bruner, Tomasello, etc.)
• More studies are needed, but so far, leaner
  interpretations of communication in apes and
  children with autism fit best.

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(No Transcript)
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• Hare and Tomasello (2004) hid food in one of two
  buckets and then, in one condition, pointed to
  the bucket containing the food in order to inform
  the ape where it was. In this case, as in
  previous studies, the apes searched randomly.
  The novelty was in the second condition. Here E
  began by establishing with each ape a competitive
  relationship over the food, and then later
  reached toward one of the two buckets in a vain
  attempt to open it (the reaching was impeded).
  Now, surprisingly, even though the superficial
  behavior of the human was highly similar to that
  in the pointing condition - in both cases the
  human stretched out his arm toward the correct
  location - the apes in this condition suddenly
  knew where the food was. In this case, the apes
  had to discern the goal of the human - to get
  into that bucket - and then infer why he wanted
  to do this because there is something good
  inside. This cognitive process is quite complex
  on its own terms, but the key point is that it
  includes none of the crucial elements of shared
  intentionality from our analysis of the
  interpersonal structure of pointing. The apes'
  understanding of the human's reaching is of
  individual goals or intentions toward things, not
  communicative goals or intentions toward
  themselves. There is thus no question of a joint
  attentional frame or common ground, or of
  communicative or referential intentions, or of
  any assumptions of helpfulness or other
  interpersonal motives.
• Following Tomasello et al. (2005), we may thus
  attempt to characterize the essential elements in
  the comprehension and expression of human
  pointing as a communicative act by viewing them
  from the perspective of shared intentionality.
  Whereas apes' understanding of the goal of a
  reaching person is essentially an act of
  individual cognition, humans' understanding that
  others are pointing out things for them because
  of their presumed relevance to some common ground
  or joint attentional frame is an act of
  interpersonal cognition involving shared
  attention and knowledge, along with some motive
  for helping or sharing with others.

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Infants
Chimpanzees

• Infants pass this test.