Summary of results.

Reiterate goal of investigation: How general is anticipatory behavior observed by Land & McCleod?Found: Untrained subjects exhibit similar behavior in a simple task catching a ball.Ss look at hands of thrower and make a saccade to the neighborhood of the bounce around or just prior to the bounce. Then pursue the ball briefly before catching. How much anticipation? Normal saccadic latency is about 200 msec. Saccade left close in time to throw – also anticipatory.Landing point of anticipatory saccade – above the bounce point – probably targeting a Location in space where the ball will pass after it bounces.Why do Ss do this?

Comparison with LandExplanation of differences?

Discussion

Importance of anticipation.Necessary because of sensory-motor delays.

Importance of learning. Without learning the properties of a dynamic world, it would be impossible to make predictive eye movements.This learning is probably driven by the dopaminergic circuits in the basal ganglia

Brain areas involved?

Probably frontal areas and supplementary motor cortex.

Other things to think about:How regular is the sequence of movements? Same on every trial? Same for all Ss?

What conclusions can be drawn from this?

People look to where their social partners look. The coordinationof visual attention among social partners is central to manycomponents of human behavior.

Contemporary research concentrates on gaze following as the essential mechanism through which visual attention is socially coordinated. Here we present evidence from one-year-olds and their parents for an alternate pathway, through the coordination of hands and eyes in goal-directed action.

Yu & Smith PLOS ONE 2013

By tracking the momentary visual fixations of each participant, wecould measure how often they attended to the same object at thesame time, the specific cues used to coordinate visual attention, thetemporal lags in following a partner’s shift in visual attention, andthe potentially different roles of parents and infants.

The sharp peak in coordinated looking around 0 ms and the higher recurrence relative to baseline within a 5 sec lag in each direction implicates strongly coordinatedlooking behavior between infants and parents.

Parent looking at ROI

Child

look

ing

at R

OI

Calculation of recurrence lag profile.

Put a black dot in the square if parent and child are both looking at an ROI at time t.Count the proportion of black dots.

Similar to cross-correlation – how likely are baby and parent likely to be looking at thesame thing at the same time, or with some delay.

Parents and infants looked at the same toy object at the same time .33 and .42 of the time by the synchronous and sustained measures respectively;however, they looked at each other’s faces at the same time only0.10 and .09 of the time by these two measures respectively.

In sum, the overall pattern shows that one yearolds and their parents are equal partners with both manuallyengaged with the objects and both leading and rapidly followingshifts in their partner’s focus of visual attention.

How often a follower looked to the leader’s face prior to a sustained jointattention episode.

Child looks at parent’s hands prior to joint attention

Mutual gaze doesn’t predict jointAttention.