Experimental studies of a perceptual anomaly

This paper reports an investigation of the relation of the rotation effect to visual field defects and to “oculo-motor” defects. The “rotation effect” refers to the tendency to reproduce abstract designs correctly but in a misoriented position. The subjects consisted of 61 normals, 58 non-brain-damaged functionally disordered patients, 24 patients with visual field and “oculo-motor” defects and 24 brain-damaged patients without such defects. The influences of differences in age, Wechsler vocabulary, and Wechsler Block Design ability were partialled out by means of discriminant function technique. The outstanding finding was that, after this was done, the brain-damaged group with visual field and “oculo-motor” defects rotated far more than the other three groups, which were only slightly differentiated from each other. On consideration of further analyses of the data, it was concluded that it was reasonable to look upon visual field defects and “oculo-motor” defects as sufficient causes of rotation and that it was unnecessary, as Shapiro had previously done, to postulate a generalized increase in the strength of inhibitory processes in brain-damaged subjects. The general implications of these findings are discussed.