Modulation of unilateral neglect as a function of direction of object motion.

Unilateral neglect is a disorder involving difficulty in attending to the side of space contralesional to brain injury. Two recent experiments have shown that task-irrelevant background motion reduces neglect on line bisection tasks; however, task-relevant motion has not been assessed. We investigated the effect of task-relevant object motion on left neglect using a moving cube presented on a computer screen. Subjects responded to cued corners of the cube as it moved across the screen. Direction of cube motion had a significant impact on the magnitude of neglect. Responses to left hemispace targets appearing on a leftward moving cube were equal to patients' fastest responses. In contrast, responses to left hemispace targets appearing on a rightward moving cube were the slowest of all responses. These results demonstrate that contralesional object motion is capable of normalising neglect patients' detection of contralesional targets.