Prodded by Reality

Harvard psychologist Dan Gilbert wrote:

"In a study conducted by Sukhwinder Shergill and colleagues at University College London, pairs of volunteers were hooked up to a mechanical device that allowed each of them to exert pressure on the other volunteer's fingers.

The researcher began the game by exerting a fixed amount of pressure on the first volunteer's finger. The first volunteer was then asked to exert precisely the same amount of pressure on the second volunteer's finger. The second volunteer was then asked to exert the same amount of pressure on the first volunteer's finger. And so on. The two volunteers took turns applying equal amounts of pressure to each other's fingers while the researchers measured the actual amount of pressure they applied.

The results were striking. Although volunteers tried to respond to each other's touches with equal force, they typically responded with about 40 percent more force than they had just experienced. Each time a volunteer was touched, he touched back harder, which led the other volunteer to touch back even harder. What began as a game of soft touches quickly became a game of moderate pokes and then hard prods, even though both volunteers were doing their level best to respond in kind.

Each volunteer was convinced that he was responding with equal force and that for some reason the other volunteer was escalating. Neither realized that the escalation was the natural by-product of a neurological quirk that causes the pain we receive to seem more painful than the pain we produce, so we usually give more pain than we have received.

- Quoted in Send, by David Shipley and Will Schwalbe, pp. 188-189