John’s hand sometimes acted as if it had a mind of its own: unbuttoning his shirt, stealing food from his dinner guests; all on its own. It wasn’t always a burden of course, and as it squeezed his therapists left breast he made a mental note to low-five it later.
Alien hand syndrome is actually a real condition. If certain regions of the brain become damaged people can find themselves unable to prevent either one or both of their hands from performing automatic utilisation behaviours.
We train ourselves to utilise objects in our environment without thinking about it; our hands seem to know what to do with mugs, door handles and wallets without our consciously directing them. Usually we can control when these behaviours are manifested; however, the presence of lesions in particular regions of the brain can cause an inability to prevent them. This leads to the utilisation behaviour manifesting whenever presented with the relevant stimulus. Sufferers of alien hand syndrome find themselves grabbing on to door handles, unable to let go; pinching food off of other people’s plates; or rifling through other people’s wallets. It’s such an odd condition you’d swear it was fiction, but it really isn’t!