Effect of Unilateral Above-the-Knee Amputation on Perception of Verticality 1

Abstract

This study was concerned with the effect of unilateral amputation on space perception. Thirteen left above-the-knee amputees were compared with 13 right above-the-knee amputees on perception of the visual vertical under conditions of body erect, and 30° left and right body tilts. Results showed that, when the body was erect, the apparent vertical was significantly displaced in a direction opposite the side of amputation, while under conditions of left- and right-body tilt, right above-the-knee amputees displaced the apparent vertical opposite to the body tilts to a greater extent than left above-the-knee amputees. The findings with amputees were contrasted with hemiplegic patients and discussed with reference to the sensory-tonic field theory of perception.