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Gestural%20communication%20in%20children%20and%20chimpanzees

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Title: Gestural%20communication%20in%20children%20and%20chimpanzees


1
Gestural communication in children and
chimpanzees
2
  • 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)

3
Outline
  • Development
  • Theoretical issues
  • Pointing
  • Pointing basics
  • Infants
  • Apes
  • Children with autism

4
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)
5
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)
6
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)
7
  • 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)

8
  • 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)

9
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.

10
  • 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)

11
Importance of shared context (what why)
12
Importance of shared context (what why)
13
  • Shared context can help you determine what the
    other is pointing to (and often why)
  • Expressions of attitude can also help you
    determine why.

14
Attitude (observable cue to motive why?)
15
Attitude (observable cue to motive why?)
16
  • 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)

17
  • 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)

18
  • 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.

19
  • 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)

20
Complexity of pointing
21
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)
22
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)
23
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

24
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)
25
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

26
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)
27
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.

28
Experiments
  • Common ground
  • Informative (helping) motive
  • Absent referents
  • Communicative intention

29
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.

30
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.

31
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
32
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.

33
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.

34
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.

35
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

36
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
37
Complexity of infant pointing
  • Common ground
  • Many motives, meanings, including to inform
    others.
  • Absent referents
  • Understanding of communicative intention (tree
    example)

38
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.

39
  • 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)

40
  • 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.

41
  • 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).

42
  • 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).

43
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.

44
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45
  • 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.

46
Infants
Chimpanzees
  • Infants pass this test.
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