The hemispheres of the human brain.

(a) The cerebral hemispheres and their connection by the corpus callosum. Note: The right hemisphere controls the left side of the body, while the left hemisphere controls the right side. (b) Split-brain patient being tested for hemispheric dominance. By using this apparatus, Roger Sperry and his collaborators showed that the left and right cerebral hemispheres have different capabilities. When a split-brain patient held an object in his right hand but could not see it or touch it with his left hand, he could give it a name (for example, an apple). When he held another object in his left hand, he could describe it (for example, rough or smooth) but could not name it.