Roger Sperry. Portrait of Roger Wolcott Sperry (1913-94), American neurologist. Sperry studied the two brain hemispheres, which each control half the body. He studied animals & humans who had had the connections between the two hemispheres cut as an epilepsy treatment. He found that creatures with 'split brains' behave as though they have 2 independent brains. Reactions to stimuli on one side of the body had to be learned again if the stimuli were applied to the other side. He found that the left hemisphere controlled language, writing and reasoning whilst the right is more responsive to music, face and voice recognition. Sperry was awarded the 1981 Nobel physiology prize.