Use of left vs right hand in responding to lateralized stimuli in unilateral neglect

Abstract

Previous research suggests that contralesional limb activation may reduce the degree of visual neglect shown by hemi-inattentive subjects. The present study examines whether minimal assisted-left-limb activation (pressing a response key with the hemiplegic hand, aided by the ipsilesional hand) resulted in lowered response latencies on the neglected side in a group of six patients showing unilateral left visual neglect. The study was carried out using a simple computerized test of speed of detection of lateralized stimuli, with responses being made on a key located at the body midline. In five of the subjects, there was no evidence of relatively faster response times to contralesional stimuli when the contralesional limb was involved in the responses. In one of these five subjects, there was no hemiplegia, and hence full use of the contralesional limb. Only in one subject did an interaction appear between the side of presentation of the stimuli and limb used. In this case, a small but significant tendency appeared for the subject to make relatively faster responses to left-sided stimuli when using the left hand to make responses.