Abstract
Background: Previously, we found that 2-year-old toddlers with ASD are much better at visual search than age-matched typically developing (TYP) toddlers (Kaldy et al., 2011, Dev Sci), primarily because they had greater attentional focus (shown by pupillometry, Blaser et al., under revision). The current study directly tested the idea of whether toddlers with ASD are less distractible than TYP toddlers during search. Methods: Stimuli consisted of single-feature (color [red/blue] and shape [circle/rectangle]; set sizes: 9, 13) and feature conjunction trials (set sizes: 5, 9, 13, 17) in mixed blocks. Search displays were presented for 4 s, then the target (always a red circle) rotated; acting as feedback and reward (a unique aspect of our paradigm is that it does not require verbal instructions, making it ideal for populations with weak language skills). Crucially, in the second half of the block of trials, a novel, oddball item was presented in place of one of the usual distractors. A Tobii T120 eye-tracker recorded eye movements. In Study1, 14 TYP toddlers participated (mean age: 24 months) and the oddball item was defined as the conjunction of features present in the display that was disjunct from the target [i.e. a blue rectangle]. In Study2, 13 ASD and 16 age-matched TYP toddlers participated (diagnosis was confirmed by ADOS, mean age: 26 months). Here, the oddball's salience was raised by giving it a novel color [i.e. an orange or green rectangle]. Results: We found that even the less salient oddball of Study1 can have a distracting effect. In Study2, while both groups often fixated the salient oddball, performance of toddlers with ASD was significantly less degraded. Discussion: Our findings provide direct evidence – at the earliest age the condition can be reliably diagnosed – for a stronger resistance to distraction in a search task in ASD.
Meeting abstract presented at VSS 2014