Graphic neglect--more than the sum of the parts

Patients who seem to "ignore" objects or people on one side of space have been described in the medical literature for well over a century. The term "visuospatial neglect" is now used to describe the cluster of behaviors whereby patients after unilateral cerebral lesions (most frequently of right parietal cortex) fail to attend or explore (predominantly) the side of space contralateral to the lesion. Although the condition comprises a complex disruption of space-related behaviors, the prevailing view was that the different symptoms could be accommodated in terms of damage to one of three different cognitive mechanisms mediating attention (e.g., K. M. Heilman and E. Valenstein, Ann. Neurol. 5: 166-170, 1979), intention (R. T. Watson, E. Valenstein, and K. Heilman, Ann. Neurol. 3: 505-508, 1978), and/or representation (E. Bisiach, Q. J. Exp. Psychol. 46: 435-461, 1993). The general consensus favors an attentional deficit but the notion of attention has always proved conceptually slippery and difficult to operationalize (P. W. Halligan and J. C. Marshall, Cogn. Neuropsychol. 11: 167-206, 1994a). In this paper, we consider how drawing performance after right brain damage in patients with "visual neglect" reveals the involvement and interplay of several cognitive deficits, including aspects of mental representation and spatial awareness.