Distractor-dependent frontal neglect.

The effect of distractor load on visual search was examined in a patient with visual neglect following infarction of the right frontal lobe. The spatial extent of his left-sided neglect was modified greatly by changing stimulus attributes. When targets were highly discriminable compared to distractors, or distractor density was low, or when the subject was asked to cancel distractors as well as targets, he was able to direct his search to the extreme left of search arrays and there was little or no evidence of neglect. By contrast, similar changes in distractor load had little or no effect on the neglect of a patient with a fronto-parietal lesion. These findings suggest that distractability towards ipsilesional stimuli may be an important component of neglect in individuals with only frontal lobe injury.