| Summary: | A forced-choice reaction time (RT) task was used to examine the relations between covert orienting (shifts of visual attention independent of eye movement) and filtering (the inhibition of processing of irrelevant stimuli) components of attention in persons with Down syndrome (n = 17) and children of average intelligence (n = 17) matched for mental age (MA), (MA = approximately 5 years). Conditions varied with regard to presence or absence of distractors, and the validity (valid, invalid, or neutral) of location cues. RT/p(correct) scores of both groups were longer in distractor-present conditions and in conditions when the location cue provided incorrect information (invalid cue). In addition, RT/p(correct) scores of both groups were longer when it was necessary to simultaneously search for a target and filter out irrelevant information, than when each of these attention demanding tasks was utilized separately. However, there were no differences in performance between persons with Down syndrome and MA matched children of average intelligence. This evidence is used to challenge the notion of an overall deficit in selective attention abilities in persons with Down syndrome as compared to MA matched children of average intelligence. Findings are also discussed in terms of their support for a capacity sharing relationship between covert orienting and filtering.
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