Perceptual and premotor factors of unilateral neglect.

Right-brain-damaged patients showing unilateral neglect underwent a specifically devised line-bisection task that allowed uncoupling of the direction of visual attention from that of hand movement. This made it possible to isolate and separately assess perceptual and premotor factors of the disorder. Comparison of experimental and radiologic data suggested that premotor factors were more pronounced in patients with lesions involving the frontal lobes than in patients with lesions confined to postrolandic areas. The technique employed is compatible with bedside examination and provides data useful for standard assessment of neglect symptomatology for both clinical and experimental purposes.