Some determinants of visual neglect.

Some patients with brain lesions do not respond normally to stimuli from the side opposite their lesions, and behave as though the stimuli were not present. This phenomenon is called neglect or inattention. A number of manifestations of neglect occur: neglect on double simultaneous stimulation (visual, auditory, tactile), neglect during reading, drawing, picture description, and the complex phenomena of neglect of the opposite side of space and neglect of the opposite half of the body. Each of these types of neglect involves particular neurological functions and differs in some way from the others. The present paper will contribute to the understanding of a type of neglect which was originally observed during matching-to-sample tasks with visual choices. Not only did some patients neglect the choices on the side opposite their lesions, but these patients did not show their neglect on all tests. The neglect appeared when the patient, for some other reason-for example, aphasia-could not do the test correctly. The study also brings some evidence to the problems of whether neglect can occur in the absence of a 'primary' sensory defect and whether neglect occurs after lesions of either hemisphere or only or mainly after lesions of the minor hemisphere.