Selective Attention and Perceptual Load in Autism

Background: When we focus our attention on an aspect of the environment it is important to be able to ignore potentially interfering distractors (selective attention). Ignoring distractors though is not always something that can be done at will, and it does seem that under some circumstances we process distractor information whether we like it or not (e.g. we hear our own name mentioned in a conversation we are not focusing on at a cocktail party). Recent research by Lavie (1995) has shown that the degree to which distractors are processed depends on how much of our finite attentional resource is allocated to the task we are focussing on (perceptual load theory).

Objectives: This study examined the effect of perceptual load on selective attention within Autistic Spectrum Disorders (ASD). Previous studies suggest that individuals with ASD might find it difficult to ignore distractors (Burack et al 1994), although no studies have yet taken into account the perceptual load of the focus task. The issue of the special status of social stimuli when they are the distractors was also addressed. Typical individuals find these hard to ignore whatever the perceptual load of the task they are focussing on.

Methods: Young adults with ASD and typically developing adults performed visual attention tasks with varying perceptual load and distractor types.

Results: Preliminary results suggest that individuals with ASD continue to be affected by distractors at higher levels of perceptual load than typically developing controls. With social stimuli, a different pattern is seen: typical adults are distracted irrespective of perceptual load while ASD adults show no such ‘special case’ for faces.

Conclusions: The results obtained appear to suggest increased perceptual capacity in individuals with ASD.