Inhibitory mechanisms in autism spectrum disorders: typical selective inhibition of location versus facilitated perceptual processing

Background: This study examined the inhibitory control mechanisms of selective attention in autism spectrum disorders. Two issues were engaged: First, we extend previous findings of normal inhibition of distractor identity in autism by examining whether inhibition of spatial location is also spared. The second issue concerns the selectivity of inhibition. in non-clinical participants inhibition is selectively directed to the properties of the distractor that compete for the control of action; we examined whether individuals with autism also show normal selectivity of inhibition. Method: A negative priming task was used to examine selective spatial inhibition in participants with autism relative to matched non-clinical controls. Results: We discovered that inhibition of distractor spatial location is within normal limits in autism, as is the ability to selectively direct inhibition to task-relevant stimulus features. In addition, we unexpectedly found that the irrelevant perceptual feature of colour produced a facilitation effect in autism, which has not been observed previously in typical controls. Conclusions: Evidence of colour facilitation implicates more fluent, but presumably less adaptive, perceptual processes in autism.