The researchers didn't want to actually hurt anyone, so they took advantage of a strange phenomenon: if you put your index and ring fingers in warm water and your middle finger in cool water, you will think your middle finger is burning.
The researchers used the illusion to fool people into thinking their middle fingers were extremely hot and then removed their hands from the water. Some participants touched fingers from one hand to another, while others touched someone else's hand.
Those who touched all three fingers to the same fingers on the other hand felt 64 percent less painful heat, the investigators found.
"Self-touch caused the integration of both hands together into a coherent body representation, which caused a reduction in heat pain," Kammers said.
The study shows that "we can think creatively about how to treat pain by changing what the brain understands to be true," said Beth Darnall, an assistant professor at Oregon Health & Science University who is familiar with the study findings. "We can trick the brain out of pain by making it believe certain things about itself."
Doctors already use an approach called "mirror therapy" to reprogram the brains of amputees who suffer from phantom limb pain.
More widespread use of fooling the brain to treat pain is "a little bit down the road," Darnall said, but she thinks studies like this one are paving the way.
The study findings were published online Sept. 23 in the journal Current Biology.
The U.S. National Library of Medicine has details on phantom limb pain.
SOURCES: Marjolein P.M. Kammers, Ph.D., Institute of Cognitive Neuroscien
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