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Pointing

Adults can use pointing to ...

  • request
  • inform
  • initiate joint engagement (‘Wow! That!’)

Tomasello calls the third kind 'declarative'.

Infants point from around 11 or 12 months of age, and point to all of these ends ...

From around 11 or 12 months of age infants spontaneously point to request, inform and initiate joint engagement \citep{Liszkowski:2007mm}.
Infants spontaneously point from around 12 months.
Here is a situation in which a child is playing at her table. Then something appears from behind a sheet. The infant spontaneously points at it.

Liszkowski et al 2004, figure 2

Infants point to intiate joint engagement Liszkowski et al 2006.

Why do infants point?

Liszkowski’s idea: find out by seeing what satisfies them.

hypotheses:

  1. for themselves

    (prediction: ignoring them makes no difference)

  2. to draw attention to themselves

    (prediction: looking at them is sufficient to satisfy them)

  3. to direct attention only

    (prediction: looking at the referent is sufficient)

  4. to initiate joint engagement

    (prediction: looking at them and the reference is sufficient)

‘Four hypotheses about what infants want when they point were tested. First, on the hypothesis that infants pointed for themselves (see above), E neither attended to the infant nor to the event (Ignore condition). Second, on Moore and D’Entremont’s (2001) hypothesis that infants do not want to direct attention and just want to obtain attention to themselves, E never looked at the event and instead attended to the infant’s face and emoted positively to it (Face condition). Third, on the hypothesis that infants just wanted to direct attention and nothing else, E only attended to the events (Event condition). Fourth, on our hypothesis that infants want to share attention and interest, E responded to an infant’s point by alternating gaze between the event and the infant, emoting positively about it (Joint Attention condition).’ \citep{Liszkowski:2007mm}
‘When interacting with an adult who always reacted consistently in one of four ways, 12-month-olds pointed most often across trials if the adult actively shared her attention and interest in the event (Joint Attention condition)’ \citep[p.\ 305]{liszkowski:2004_twelve}
‘Analyses of infants’ points within each event revealed a complementary set of results. In the conditions not involving joint attention, infants repeated their point more often. This repeating behavior presumably indic- ates that they were dissatisfied with the adult’s response, and so they were persisting in their pointing behavior hoping eventually to obtain the desired response (which was presumably joint attention, since children did not repeat themselves very often in this condition).’ \citep{Liszkowski:2007mm}
Now imagine an experiment with four conditions.
In each condition, there are several trials involving something appearing and, hopefully, the infant pointing at it.
So how do the conditions differ?
In one condition, the experimenter ignores the infant when she points.
In another condition, the experimenter looks at the infant only.
What predictions should we make?
If infants point to draw attention to themselves, what can we predict?
They should be more satisfied in these conditions.
They should be less satisfied in these conditions.
But how can we measure satisfaction?
Within a trial: less satisfied with response should lead to more pointing.
Across all trials: more satisfied with responses should make it more likely that pointing will occur in a trial (at least once).
If infants point to initiate joint engagement, what should we expect then?
Satisfied in this condition and not in any other.
So here's the setup again (but schematically this time).

Liszkowski et al 2004, figure 1

And here is the first key finding: more pointing overall (across trials) when there's joint attention.
[*todo: redraw Ulf's figures and put this & next on one slide]

Liszkowski et al 2004, figure 3

And here is the second key finding: less pointing within a trials when there's joint attention.

Liszkowski et al 2004, figure 4

12-month-old infants point not only to request but also to initiate joint engagement.

(And to inform.)

Why is this significant?
Because it implies two things:
First, it implies that infants' pointing is referential communication; that is, communication about an object.
(Contrast sharing a smile; we're communicating, but not necessarily referring.)
Second, it implies that infants have some understanding of joint engagement.
I'll come back to this in later.