Right hemisphere specialization for mental rotation in normals and brain damaged subjects.

Hemisphere specialization for mental rotation was investigated utilizing Shepard's (1971) paradigm. In each of two experiments, the procedure involved presenting pairs of novel non-verbal stimuli at various angles of disparity. Subjects were instructed to construct a mental image of one stimulus, rotate this image, and judge whether or not the image was a congruent match with its mate. Both response time and accuracy were measured. In Experiment 1, the testing of right-handed normals revealed a significant left visual field advantage for accuracy (p less than .0001) and response time (p less than .05). In Experiment 2, a comparison of right parietal lesioned patients with both left parietal lesioned patients and matched normal controls likewise revealed significant right lesion effects for accuracy (p greater than .0001) and response time (p greater than .01). Right hemisphere specialization for mental rotation was documented for both normals and brain damaged subjects.