Hemispheric cooperation in visuospatial rotations: evidence for a manipulation role for the left hemisphere and a...

A survey of mental rotation strategies in 210 normal subjects showed a strong tendency for right-handers to prefer rotating an object on the right and vice versa for left-handers. The differential functioning of the cerebral hemispheres during mental rotation was then assessed in 42 subjects by means of tachistoscopic presentation of two geometrical figures separately to the left and right visual fields--one of which was gravitationally stable and the other unstable. Performance was better when the unstable object was presented to the right visual field and the stable object to the left. This finding is interpreted as indicating more efficient hemispheric cooperation when the active manipulation of a mental image is performed by the left hemisphere, while the reference role is carried out by the right hemisphere.