VIBROTACTILE REACTION TIMES IN UNILATERAL NEGLECT

Patients with left hemispatial neglect resulting from right hemisphere damage performed a vibrotactile reaction time (RT) task with the stimulated and responding (right) limb placed either ipsilaterally in right hemispace, or across the midline in contralateral (left) hemispace. In 8 patients who had undergone little or no rehabilitative training, responses made on the left were very much slower (by an average of 45 ms) than responses made on the right. Four out of 5 rehabilitated patients who had been taught compensatory strategies to overcome their difficulty in attending to events on the left, and who were tested with eyes open, were faster on the left, a pattern opposite to the small (9 ms) but significant right-side advantage shown by normal subjects. However, when 4 of the rehabilitated patients were tested with their eyes closed, their performance reverted to that shown before rehabilitation, that is, a substantial left-side disadvantage. Overt and covert attentional strategies and spatial asymmetries in normal subjects and patients with unilateral attention defieits are discussed. The vibrotactile RT task provides a promising method for quantifying disability during the various phases of the neglect syndrome.