Spatial anisometry and representational release in neglect

Abstract This chapter argues that disruption by brain damage occurs in patients with spatial neglect. It begins by discussing psychophysical principles in general, and with reference to patients with neglect. It then concentrates on line bisection tasks, with respect to the graded distortions, or anisometry, of the mental representations of these patients. Next, it describes whether the abnormal gradients of attention in neglect are distributed over external space or over internal representations. Finally, it reports the cross-over phenomenon, which refers to a paradoxical behavior seen when most neglect patients bisect short lines. It is proposed that the cross-over phenomenon follows from a general psychophysical principle and is not confined to visual spatial stimuli. Lastly, it suggests that the cross-over phenomenon points to an underlying instability of mental representations in patients with neglect and to ways in which perceptions are influenced by the context in which stimuli are apprehended.