Who is Split-brain patients from Incognito: The Secret Lives of the Brain and what is their importance?

Split brain patients are people who have had the left and right halves of their brains surgically separated. While they are able to function normally in most cases, the separation of the hemispheres sometimes causes behavior that makes it appear as if two separate brains are inhabiting the same person. A person may button up a shirt with one hand while unbuttoning it with the other, for example, and be unaware of it or unable to explain why they are doing it.