Lateral and radial neglect as a function of spatial position: a case study.

We report a case of severe visuo-spatial neglect after multiple right-hemisphere infarcts. Experiment 1 demonstrated that the magnitude of transection displacement for the bisection of horizontal lines could be modulated by the lateral position of those lines within peripersonal space. As found in previous studies, neglect was attenuated when the true centre of the lines was to the right of the patient's midsagittal plane. In Experiment 2, radial lines were presented in left, middle, and right space. All bisections were placed too far from the body, but the magnitude of this effect increased significantly from right to left space. In Experiment 3, horizontal lines were presented at three distances within peripersonal space; there was a small but reliable reduction of bisection error for the most distally-placed stimuli. These results suggest that unilateral right hemisphere damage can distort the representation of space (and action therein) more extensively than is implied by the term left neglect.