A Newtonian model of perceptual distortion in visuo-spatial neglect

We propose a simple mathematical model that describes how unilateral brain damage distorts the representation of length in two-dimensional space. The model was tested on eighteen normal adults and six patients with left visuo-spatial neglect after right hemisphere lesion. The subjects bisected lines at eight orientations from vertical to horizontal and the displacement of their transections from true centre was expressed as a function of inclination. Although accuracy differed considerably from patient to patient, sinusoidal functions of the predicted form were found in all cases. The pattern of distortion is an exaggeration of one subtype of normal performance, and is fully consistent with the hypothesis that the cerebral hemispheres have antagonistic attentional biases.