DESCRIPTION (Adapted from the Investigator's Abstract): A series of 18 experiments are designed to systematically characterize neglect patients ability to process visual information within their neglected field. These studies are based on a convergence between recent empirical evidence of preserved visual information processing in the contralateral field of patients with neglect, and recent theories and data regarding attention and the binding of information in normal vision. Ninety patients with neglect, 45 patients with hemianopsia and 90 matched control subjects will be tested with four sets of studies that are designed 1) to assess processing of visual features and their binding into objects; 2) the processing of space and its binding to features and objects; 3) the processed involved in preparing a response an binding it to objects; and 4) the process involved in preparing a response and binding it to specific spatial locations. The results will be relevant to clinical evidence of object versus spatially centered neglect and attentional versus intentional neglect. Examining each of these processes independently will allow further specification of the information processing deficit in neglect and help fit the disorder more clearly within the taxonomy of perceptual and attentional processes developed in normals. The experiments include variations of previously developed yoked implicit and explicit paradigms that have been used with neglect patients in the PI's laboratory, as well as novel procedures extensively piloted in normal subjects. The data should provide a new understanding of the clinical phenomenon of neglect as well as basic information about the neuropsychology of attention and higher visual processes. The data should also have relevance to understanding normal operations of these processes.