DISSOCIABLE COORDINATE FRAMES OF UNILATERAL SPATIAL NEGLECT - VIEWER-CENTERED NEGLECT

Detailed analyses of reading and nonlexical tasks by three patients wi th unilateral spatial neglect (USN) secondary to stroke indicate that the USN in each of these patients affects the left side (contralateral to brain damage) of the viewer, with respect to the viewer's head, mi d-sagittal plane of the body, or line of sight. In one case, the negle ct was further specified as concerning the left side of the viewer's l ine of sight (the left half of her residual visual field). Thus, the f rame of reference of USN in these three cases appears to have viewer-c entered (in at least one case, specifically retinotopic) coordinates. The performance of these patients is contrasted to that of other patie nts in the literature whose USN appears to have a frame of reference w ith stimulus-centered or object-centered coordinates. These results ar e interpreted within a model of visual processing (adapted from Marr, 1980 and others) with at least three coordinate frames. It is argued t hat USN can affect one or more of these coordinate frames independentl y. (C) 1998 Academic Press.