Kate Wilmut, John Wann, Janice H. Brown University of Reading k.wilmut@reading.ac.uk

1. The gap effect size for eye and hand latencies 16 12 8 Gap effect (ms) 4 0 Look and Hit Look and Hit Look Hand latencies Eye latencies Waits for fixation 1000ms GAP OVERLAP 200ms 200ms Saccadic latencies for look and look and hit responses 450 400 600ms 600ms 350 latency (ms) 300 250 200 Overlap Gap Look Look and hit ATTENTION DISENGAGEMENT IN 36 MONTH OLDS Kate Wilmut, John Wann, Janice H. Brown University of Reading k.wilmut@reading.ac.uk • Introduction • Objective • Many studies have looked at attention disengagement, but none have focused on 36 month-olds. • At this age children are becoming more active and are refining both visual and motor skills. • This research investigated attention disengagement in 36 month-olds for both simple eye movements and the integration of a hand movement. • Attention Disengagement • In order for a eye movement to be made attention must be disengaged, shifted and re-engaged at a new target location (Posner, 1980). • The gap paradigm measures attention disengagement. • Gap paradigm • Gap trials; temporal gap between fixation offset and target onset. • Overlap trials; fixation offset and target onset overlap (see below). • A shorter saccade latency is seen in gap trials, as attention is disengaged prior to target onset. • This effect has been found in adults (Pratt et al., 1999; Bekkering et al., 1996) and newborns (Farroni et al., 1999). • Development of attention disengagement • Hood and Atkinson (1993) proposed that shifts of attention are driven by a dual process. • One is triggered by removal of fixation (gap condition) • The other is triggered by the appearance of a target (overlap condition) • Three months-olds show prolonged latencies in overlap trials suggesting the second process has a later developmental onset. • Schul et al (2003) found that the ability to disengage attention improves throughout school-age years (7-18). • Methods • The gap paradigm was made into an interactive game and used to look at attention disengagement in 36 month-olds (n=18). • LED’s embedded in a Perspex board • One central light – green • Six peripheral lights – red (decorated with pictures of snowmen) • Children looked at or hit targets (plastic hammer) when they lit up. • Gap effect size • Gap effect size refers to the difference in latency between overlap and gap trials. • For eye latencies the size of the gap effect was much bigger in the look and hit condition (127ms) than for the look condition (60ms) (t(17)=-3.370 p<0.01). • N.B. The gap effect size in adults on the same task was similar across the two conditions (~54ms) • The gap effect for hand latencies shows a large variability. Display as seen by subjects “Look at the snowman who has the red tummy” or “Hit the snowman with the red tummy” • Discussion • Saccade latencies • A larger gap effect was found in the look and hit response than in the look response (not seen in adults). • When using eye movements alone toddlers display a mature pattern of response (similar to that seen in adults), this is not the case when a hand movement is used. • This suggests that toddlers are still refining their disengagement mechanisms such that the process needed for disengagement in overlap trials is not fully developed. • Hand latencies • The lack of a gap effect in hand latencies (a gap effect has been found in the hand latencies of adults, Bekkering 1996) may be due to the variation in latency. • The huge variation seen in all aspects of hand movements suggests an overall immaturity in the combination of visuo-spatial and motor systems. • Conclusion • At 36 months children are still refining their disengagement mechanisms so when a hand movement is added to an eye movement attention disengagement is less skilled. • In addition manual responses are unrefined and variable. • Results • Saccade latencies • Significant difference between saccade latencies on gap and overlap trials. • Look, F(1,17)=14.986 p<0.01 • Look and hit, F(1,17)=47.147 p<0.01 Order of events for gap and overlap trials • Hand latencies • No significant difference between gap and overlap trials. • Large variability in hand latencies (ms), accuracy error (cm), heading error (o) and in the number of adjustments.