The next time you are having an injection in your arm, take a look while the needle goes in because it reduces the pain being felt, it has been claimed.
Scientists from University College London and the University of Milano-Bicocca, Italy, found that simply looking at your body can reduce pain.
Flavia Mancini, the first author of the study, placed a heat probe on the left hand of 18 participants. The temperature increased, but they were able to stop the heat by pressing a foot pedal when they began to feel pain.
A set of mirrors were manipulated to alter what the participants saw during the experiment, which was either saw their own hand, or a wooden object appearing at the hand’s location.
The researchers discovered that pain threshold was about three degrees C higher when looking at the hand, compared to when looking at another object and that the level of pain depends on how large the hand looked: the larger the hand the greater the effect of pain reduction.
Using concave and convex mirrors, they found when the hand was seen as enlarged, participants tolerated greater levels of heat from the probe before reporting pain.
Conversely, when the hand was seen as smaller than its true size, participants reported pain at lower temperatures than when viewing the hand at its normal size.
Professor Patrick Haggard said it suggested the experience of pain arises in parts of the brain that represent the size of the body and that the processing of pain is closely linked to these brain maps of the skin.
“Many psychological therapies for pain focus on the painful stimulus, for example by changing expectations, or by teaching distraction techniques,” he explained.
“However, thinking beyond the stimulus that causes pain, to the body itself, may have novel therapeutic implications.
“For example, when a child goes to the doctor for a blood test, we tell them it will hurt less if they don’t look at the needle. Our results suggest that they should look at their arm, but they should try to avoid seeing the needle, if that is possible!”
"Visual distortion of body size modulates pain perception" will be published in Psychological Science.
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