Myers and Sperry s startling conclusions about the fundamental duality of the cat brain and the informationtransfer function of the corpus callosum have been confirmed in a variety of species with a variety of test procedures. For example, split-brain monkeys cannot perform tasks requiring fine tactual discriminations (e.g., rough versus smooth) or fine motor responses (e.g., unlocking a puzzle) with one hand if they have learned them with the other provided that they are not allowed to watch their hands, which would allow the information to enter both hemispheres. There is no transfer of fine tactual and motor information in split-brain monkeys because the somatosensory and motor fibers involved in fine sensory and motor discriminations are all contralateral