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A Limit on Goal Tracking in the First Nine Months


Limits on performance are important because they provide clues about the nature of the underlying processes.

infants in their first nine months of life
can only track the goals of an action
if they can perform a similar enough action
around the time the action occurs.

Flanagan and Johansson, 2003 figure 1 (part)

To explain this I have to step back and show you something interesting about adults when they perform, and when they observe actions.
Performing actions (e.g. stacking blocks): you don't look at your hand but at the block it will pick up, or, when holding a block, at the location where it will place a block. That is, in acting the eyes move just ahead of the action.
\citet{Flanagan:2003lm} showed that the same pattern occurs when adults observe another acting. In observing an action, the eyes move just ahead of the action.
This proactive gaze is important for our purposes because it can reveal goal-tracking ...
\citet{Flanagan:2003lm} showed that ‘patterns of eye–hand coordination are similar when performing and observing a block stacking task’.

Kanakogi and Itakura, 2011 figure 1

‘Positive relative times of the arrival of gaze at the goal area indicate that gaze precedes the agent’s arrival (predictive); negative values indicate gaze arrival after agent arrival (non-predictive). Each age group is n = 12. Error bars are s.e.m.’
GH : grasping hand; BH : back of hand; MC : mechanical claw

Kanakogi and Itakura, 2011 figure 5 (part)

Kanakogi & Itakuar, 2011 show that abilities to grasp objects are correlated with abilities to track the goal of a grasping action (as measured by proactive gaze).
x-axis is alpha, grasping angle. ‘An α angle value from 90 to 180° indicates that the infant is engaged in a one-handed grasping action.’
‘The angle α is an index of the development of the one­handed grasping action and was calculated by measuring the angle of a straight line de ned by the infant’s two hands (the apex of the junction of the thumb and index nger) when crossed by an imaginary line projecting frontally from the infant (Fig. 2b). If infants grasped for the objects with their le hand, we reversed the red right­angled triangle from one side to the other side and calculated the angle α in the same way. e angle α value of 90° corresponded to a perfect alignment of the hands in a two­handed reach. erefore, the angle α value deviates from 90° towards 180°, and bigger angle α value indicates more mature one­handed grasping. If the angle α was over 90°, the infant was considered to be engaged in a one­handed grasping action.’

Ambrosini et al, 2013 figure 1 (part)

Further support for a link between action performance and goal tracking comes from a developmental study by Ambrosini et al which studied whether proactive gaze in infants is influenced by pre-shaping of the hand, and, in particular, whether it is influenced by precision grips.

Ambrosini et al, 2013 figure 1 (part)

Ambrosini et al, 2013 figure 1 (part)

By using no shaping (a fist), Ambrosini et al could treat sensitivity to whole-hand grasp and precision grip separately.

Ambrosini et al, 2013 figure 3

‘infants’ ability to perform specific grasping actions with fewer fingers directly predicted the degree with which they took advantage of the availability of corresponding pre-shape motor information in shifting their gaze towards the goal of others’ actions’ \citep[p.~6]{ambrosini:2013_looking}.

Kanakogi and Itakura, 2011 figure 1C (part)

Further, changing from a bodily action to the operation of a mechanical claw (say) undermines the goal tracking effect.
So Kanakogi & Itakuar, 2011 make two points: (i) goal-tracking depends on action capabilities; and (ii) only works for events involving biomechanically similar affectors

Kanakogi and Itakura, 2011 figure 5

If infants can only track goals of actions they can perform, what happens if you intervene on their abilities to act?

Needham et al, 2002 /

Needham et al, 2002 showed that putting ‘sticky mittens’ on 3-month-old infants (for 10-14 play sessions of 10 minutes each) resulted in their spending more time visually and manually exporing novel objects.

Sommerville, Woodward and Needham, 2005

Play wearing mittens then observe action.


Observe action then play wearing mittens.

In this study, I think infants wore the mittens for just 200 seconds (so the play sessions were much shorter than in Needhman et al, 2002).
The observation was based on this study, which we saw earlier

Woodward et al 2001, figure 1

Sommerville, Woodward and Needham, 2005 figure 3

Sommerville, Woodward and Needham, 2005 figure 3

The results show that infants who played wearing the mittens first were more attentive to the goal.
From at least three months of age, some of infants’ abilities to identify the goals of actions they observe are linked to their abilities to perform actions \citep{woodward:2009_infants}.
But one potential objection to this study concerns observation vs performance. The infants who played wearing sticky mittens first had spent longer observing actions by the time it came to the violation of expectations trial. Could it be observation of action (including one’s own) rather than performance that matters?
In adults, tying the hands impairs proactive gaze \citep{ambrosini:2012_tie}; in infants, boosting grasping with ‘sticky mittens’ facilitates proactive gaze (\citealp{sommerville:2005_action}; see also \citealp{sommerville:2008_experience}, \citealp{ambrosini:2013_looking}).


It’s not really grasping

nb something gets stuck to the mittens; it's not really grasping!

Sommerville et al 2008, figure 1

To address this issue, \citet{sommerville:2008_experience} did a study in which one group had observation while the other group had performance. The participants were 10-month-old infants this time.
The materials were a bit different: so that training vs observation could be as similar as possible with respect to the causal structure exposed, there was a hook to get an object.

Sommerville et al 2008, figure 2

The results show that infants with the training paid attention to the distal goal (choice of toy) whereas those without paid attention to the choice of cane.

Bruderer et al, 2015 figures 1, 4

Experiment 1 : shows that 6-month-old infants can distinguish a phonetic contrast they have never heard before (one that occurs in Hindi but not their linguistic environments.) (The contrast used was the Hindi dental /d/̪ versus retroflex /ɖ/ distinction.)
These graphs show a difference in mean looking time between cases in which phonemes are alternated and cases in which they are not. (Iff infants distinguish, they should find the alternating phonemes more interesting.)
Experiment 2: but not when they have a tongue-controlling dummy in their mouths
Experiment 3: but yes when they have a dummy which leaves the tongue free.


I don’t think we have found strong evidence for this limit. What we can conclude, more weakly, is that there is some limiting relation linking goal-tracking and abilities to act.

infants in their first nine months of life
can only track the goals of an action
if they can perform a similar enough action
around the time the action occurs.


In infants (and adults),
goal-tracking is limited by their abilities to act.

Why is this true? Why is goal-tracking in infants (and adult) limited by their abilities to act? On the Simple View, goal tracking is a matter of thinking and reasoning about the best means to perform an action. On this View, there’s no obvious reason why your goal-tracking should be limited by your abilities to act in this way.
Although I can’t jump over a house, I can perfectly well think about different ways to do so and distinguish better and worse approaches, at least to some extent.