Search deficits in neglect patients are dependent on size of the visual scene.

Abstract

Patients with hemispatial neglect are impaired at moving their attention to a target on the conrralesional display side. In the present study, visual display area was varied independently of the number of items displayed within the area. Patients searched for the absence of a simple visual feature in displays that produce serial search performance in normals (R. Klein, 1988; A. Treisman & J. Souther, 1985; J. M. Wolfe & C. W. Pokorny, 1990). The contralesional delay was enhanced for stimulus arrays that were distributed over a larger display area, which suggests that neglect is more severe when attention has to be moved over a larger distance. The directional disengage deficit in neglect (M. I. Posner, J. A. Walker, F. A. Friedrich, & R. D. Rafal, 1984, 1987) therefore depends on the target's relative position within a display, the number of ipsilesional items competing for attention (M. Eglin, L. C. Robertson, & R. T. Knight, 1989), and the distance of the contralesional attention movements.