Now a new study shows that self-touch also minimizes more complex kinds of pain. The study comes amid a flood of experiments in the past few years showing that the body and mind work together to heal physical and mental discomfort. One major example is recent research showing that simply the act of deciding to seek help for a medical problem such as back pain or depression or sexual dysfunction can reduce the severity of that problem, even before you have received a single treatment
In the new experiment, the authors — a team led by Marjolein Kammers of the Institute of Cognitive Neuroscience at University College in London — used self-touch to reduce a complicated physical sensation called central pain. Phantom-limb pain — when your brain feels pain in a limb that has been amputated — is one kind of central pain. Dystonia, a painful movement disorder, is another.
Central pain is also the major player in the carnival-like experiment called the thermal grill illusion. In the thermal grill illusion, you are made to touch a very warm object — say, a heated-but-not-scorching grill — and then, immediately afterward, a cool object such as a room-temperature grill. Quite reliably, your brain will fool you into believing the second object is excruciatingly hot, even though nothing has happened to your flesh. The first grill wasn’t hot enough to burn, and the second is actually cool. But your brain is confused: that’s central pain. Even though the thermal grill illusion was first written about in the 19th century, neurologists have never been able to understand precisely how it works and whether it could be used in treating pain.