Variations of the egocentric reference among normal subjects and a patient with unilateral neglect

Thirty normal subjects and a patient with a left unilateral neglect were submitted to a straight-ahead pointing task in the three following trunk orientations: head and trunk aligned at 0 degree, and trunk rotated 15 degrees to the left or to the right relative to the head. The position of the egocentric reference was found to be dependent upon the trunk orientation, lateralization of the motor response and starting position, and thus on motor direction. The results are discussed with regard to egocentric hypotheses of neglect, spatio-motor cueing and scanning direction.