Split-Brain - Fascinating Fact

As I'm preparing a presentation on the Neuroscience of Personality, I'm reminded how wonderfully complex and truly amazing our 3 lbs of neuronal tissue are.  

You probably know that the corpus callosum is the information highway between the left and right hemisphere. But did you also know that when it's severed (e.g. to prevent severe epileptic seizures) your left hand may develop a life of its own?

Michael Gazzaniga showed these patients split-screen images, for example a key on the left and a ring on the right. Participants can only name what their left hemisphere sees (a ring), because that’s the thing they can consciously name.

But then their left hands started getting agitated or grabbing nurses, and eventually they figured out that the right hemisphere was trying to say something. When the items were laid out, the left hand would grab the key. When given pen and paper, the left hand would draw it.

Don't believe me? 

See for yourself: 

Image by Birger Hoppe, Flickr, Creative Commons License.