Oculomotor capture in ADHD

It is generally thought that deficits in response inhibition form an important area of dysfunction in patients with attention-deficit/hyperactivity disorder (ADHD). However, recent research using visual search paradigms seems to suggest that these inhibitory deficits do not extend towards inhibiting irrelevant distractors. Using an oculomotor capture task, the present study investigated whether boys with ADHD and their nonaffected brothers are impaired in suppressing reflexive eye movements to a task-irrelevant onset distractor. Results showed that boys with ADHD had slower responses than controls, but were as accurate in their eye movements as controls. Nonaffected brothers showed similar problems in the speed of responding as their affected brothers, which might suggest that this deficit relates to a familial risk for developing the disorder. Importantly, all three groups were equally captured by the distractor, which shows that boys with ADHD and their brothers are not more distracted by the distractor than are controls. Saccade latency and the proportion of intrusive saccades were related to continuous dimensions of ADHD symptoms, which suggests that these deficits are not simply present or absent, but rather indicate that the severity of these deficits relate to the severity of ADHD. The finding that boys with ADHD (and their nonaffected brothers) did not have problems inhibiting irrelevant distractors contradicts a general response inhibition deficiency in ADHD, which may be explained by the relatively independency of working memory in this type of response inhibition.