Abstract

OBJECTIVES Unilateral sensory neglect has been attributed to various defects, including a hemispatial attention-arousal deficit. However, support for this hypothesis has only been indirect. Therefore, the purpose of this study was to further test the hemispatial attentional-arousal hypothesis by measuring pupillary response as an index of arousal.

METHODS There were two experimental subjects with neglect and six matched controls. Stimuli (Arabic numbers) were presented on the right, left, and centre of a screen. The subjects were asked to look at the number in the centre, on the right, or left of the screen while their pupil diameter was measured.

RESULTS Unlike the control subjects, the subjects with neglect, who were aware of the left sided stimuli, did not show a pupillary dilatation when they looked at the stimulus on the left.

CONCLUSIONS Although this study provides support for the hemispatial attention-arousal hypotheses of neglect, it does not preclude the possibility that other mechanisms may also be important.