Some features of our lives just seem inviolable. Most people would never worry about failing to recognize objects they see every day, or beginning to believe that their arm does not belong to them. And yet, these are exactly the types of things that can go wrong. Body and brain functions are not physical laws like those of thermodynamics or relativity. Gravity may be here to stay, but when it comes to our behaviors and perceptions, we may be justified in being a little more nervous. So what would you do if you lost control of your own arm?
If I ask you to lift your arm, and you agree to participate in the exercise, you’ll probably see your arm start to rise. But you always feel that the arm is doing what you, as a conscious agent, want it to do.
Anarchic hand syndrome is a disturbing disorder in which patients lose the normal experience of voluntary movement. An arm can begin to move and act without the patient wanting it to, as if the limb has a will of its own. In fact, a patient will often begin fighting their own limb if it becomes uncooperative, trying to stop it from grabbing at their tissue while they blow their nose or from touching the person sitting next to them. Have a look at this video demonstrating the plight of an elderly patient in her hospital bed after she suffered a severe stroke.
In the most extreme cases, your own anarchic limb can try to kill you. One patient described her hand tearing away at her bedcovers in the night and grabbing her own neck to strangle her. The only sense she could make of her horrifying condition was to assume that her limb was possessed by an evil spirit.
Patients with anarchic hand syndrome are in the bizarre situation of knowing that their limb is their own but losing all sense of agency over it. Without the normal process of intending to perform an action, it’s hard to say that you turned on the light when you flick the switch. Your arm certainly did it. But not you.
It all links back to our sense of who we believe we are. When we use the words “I” or “me”, we normally refer to our conscious minds and experiences. It would be strange to say “I am beating my heart faster” after going for a run, even though the heart is a part of our own body. We simply say “my heart is beating faster”. But when it comes…