Through a looking glass. A new technique to demonstrate directional hypokinesia in unilateral neglect.

A line cancellation task was performed by right brain-damaged patients with neglect in two response conditions. The task was presented either in normal view or through a 90 degree angle mirror with direct view prevented. The latter decouples the direction of visual attention and of arm movement. In the mirror condition, 4 of 18 patients cancelled lines only in right hemispace which means that they directed their visual attention to the left but failed to execute movements towards contralateral hemispace--what has been termed directional hypokinesia. In contrast, 10 patients cancelled lines only in left hemispace in the mirror condition, which accords better with attention-representation deficit hypotheses. Our results support a division of the neglect syndrome according to whether perceptual or premotor deficits are predominant.