Halloween and the Rubber Hand Illusion

If you sit at a table with one arm on the table's surface and the other on your knee, then place a rubber arm on the table, positioning it as though it was yours, you can trick yourself into thinking the fake hand is your own. To do this, have a friend rub the rubber hand while they also rub the one balanced on your knee (using a similar stroke pattern). After a short time, you will feel as though the artificial hand is your own.

Several research papers have recently emerged regarding the rubber hand illusion. With an abundance of artificial arms (bestowed by stores tending to our holiday consumer inclinations), I couldn't pass up a zany opportunity: testing the rubber arm illusion on my friends and family. I purchased a plastic hand possessing surprisingly realistic pores, lines and even fingerprints. Given the ghoulish nature of the occasion, the arm also had a blood covered appearance. Here are some comments I heard while subjecting the good sports to the experiment:

“It doesn't feel like rubber.”

“It's like my hand moved up.”

“Mommy, can we stop now.”

“Huh, that's weird.”

As the brain combines visual and tactile experience it lets us know where our body is. For the majority of people, 15 seconds of synchronous sensation/observation—real and rubber hand together, results in the bizzare feeling that the hand on your knee moves to the surface of the table. In this state, the brain assumes possession of the artificial hand. And when scientists threaten to stab the “incorporated” fake hand with a needle, areas of the brain involved with anxiety and pain anticipation flare. Subjects report the worry levels synonymous with what they felt when the white coats came at their own hand with a sharp object. Similar experiments with no arm, but a virtual reality computer graphic, show subjects wincing with anticipation.

I can only imagine that these results are relevant to fields that include: 1) prosthetics (if I lost a limb, I'd surely want my doctors to know how to keep my brain from losing it—the limb that is), 2) psychotherapy (perhaps someone with the tendency to obsessively hand wash can come to grips with soiled hands if they utilize a therapy program involving a virtual system), 3) the video game industry (whether you're talking about how to get grandmothers to embrace Nintendo's Wii, or what the effects of video game violence are)—programmers, marketers and academicians, take note.

Now that Halloween is over, the arm resides in a box with cobwebs, spiders and a skull. Maybe next year, I'll tell you how to assume that glowing plastic cranium--the phenomenon after all, is not restricted to hands.