Impaired stimulus-driven orienting of attention and preserved goal-directed orienting of attention in unilateral visual neglect.

Neglect patients do not respond to stimuli presented on the side of space contralateral to the side of their brain lesions, indicating deficits to attentional or representational mechanisms. We describe a patient who shows a left neglect in normal reading and line bisection but an intact ability to locate the left end of the stimulus. Further tests showed that his seemingly intact ability to search into the "neglected" side was due to his ability to use local elements of the stimulus as cues in his serial search for the left end. The patient's left neglect was significantly reduced after he located the left end of the stimulus. In contrast, his neglect was not reduced by making the stimulus on the neglected side physically more salient. These results suggest that his neglect is due largely to an impairment of the mechanism mediating automatic, stimulus-driven orienting of attention. In contrast, the controlled goal-directed attentional search is largely preserved and can be used to alleviate neglect.