Page "Human brain" Paragraph 44

A substantial part of our current understanding of the interactions between the two hemispheres has come from the study of " split-brain patients "— people who underwent surgical transection of the corpus callosum in an attempt to reduce the severity of epileptic seizures.

These patients do not show unusual behavior that is immediately obvious, but in some cases can behave almost like two different people in the same body, with the right hand taking an action and then the left hand undoing it.

Most such patients, when briefly shown a picture on the right side of the point of visual fixation, are able to describe it verbally, but when the picture is shown on the left, are unable to describe it, but may be able to give an indication with the left hand of the nature of the object shown.