Visual filtering and covert orienting in developmentally disabled persons with and without autism

A forced choice reaction time (RT) task was used to examine the relations between covert orienting (shifts in attention independent of eye movement) and filtering (the inhibition of processing of irrelevant stimuli) components of attention in persons with autism (n = 12) and developmentally disabled persons without autism (n = 20). Conditions varied with regard to the validity of the cue (related to covert orienting) and presence of distractors (related to filtering). ?'he RT/p(correct) scores of both groups were longer in the distractor-present conditions and in conditions when a cue provided incorrect information regarding the location of the subsequent target (invalid cue). The RT/p(correct) scores of persons with autism as compared to developmentally disabled persons without autism were slower overall. However the pattern of performance of persons with autism was not significantly different from that of the developmentally disabled persons without autism. These results are inconsistent with the notions of specific deficits in covert orienting and filtering among persons with autism and indicate that certain attentional difficulties may not be unique to autism. Alternatively, they may also reflect differences in the specific mechanisms assessed in different studies. Findings are discussed in terms of the specificity of visual filtering and covert orienting impairments in autism.