Most people prefer to look away when they know something is going to hurt. However, a new research has suggested that watching during a painful procedure such as an injection can actually make it hurt less.
Simply looking at your body reduces pain, according the new study by scientists from UCL (University College London) and the University of Milano-Bicocca, Italy.
The research has shown that viewing your hand reduces the pain experienced when a hot object touches the skin. Furthermore, the level of pain depends on how large the hand looked – the larger the hand the greater the effect of pain reduction.
Flavia Mancini, the first author of the study, said "The image that the brain forms of our own body has a strong effect on the experienced level of pain. Moreover, the way the body is represented influences the level of pain experienced."
During the experiment, 18 participants had a heat probe placed on their left hand. The probe temperature was gradually increased, and participants stopped the heat by pressing a foot pedal as soon as they began to feel pain.
The scientists used a set of mirrors to manipulate what the participants saw during the experiment. Participants always looked towards their left hand, but they either saw their own hand, or a wooden object appearing at the hand''s location.
The team found that simply viewing the hand reduced pain levels: the pain threshold was about 3 degree C higher when looking at the hand, compared to when looking at another object.
Next, the team used concave and convex mirrors to show the hand as either enlarged or reduced in size. When the hand was seen as enlarged, participants tolerated even greater levels of heat from the probe before reporting pain. 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.
This suggests that the experience of pain arises in parts of the brain that represent the size of the body. The scientists' 'visual trick' may have influenced the brain's spatial maps of the skin. The results suggest that the processing of pain is closely linked to these brain maps of the skin.
The study has been published in the journal Psychological Science.