Sunday, 29 June 2008

Acupuncturists are insensitive to other people's pain (in a good way!)

When we witness other people undergoing a painful experience, our brains respond as though we are experiencing that pain ourselves. We're simulating their trauma in our own pain pathways. This is pretty handy when it comes to empathy but could be a problematic distraction for people, such as dentists and acupuncturists, who have to dish out pain as part of the help they provide to their clients.

Yawei Cheng and colleagues wondered if medical professionals learn to suppress their emotional brain response to the sight of other people's pain, thus allowing them to plough on with their professional handiwork undeterred.

Fourteen professional acupuncturists and 14 controls had their brains scanned while they watched needles being inserted into mouths, hands and feet, or less eye-wateringly, while blunt 'Q-tips' were touched against the same areas.

Consistent with past research, when the control participants watched the needle insertions, the pain regions of their brains leaped into action, as though they themselves were experiencing the pain. By contrast, there was barely a flicker of pain-related activity in the brains of the acupuncturists. Instead, their brains showed activity in frontal regions, known to be involved in emotional control, as well as memory-related areas. (When it came to the pain-free images featuring blunt Q-tips, the brains of the acupuncturists and controls responded in the same way).

The behavioural data fitted well with these brain imaging results: the control participants reported finding the needle images far more unpleasant and painful than did the acupuncturists.

It's not that the acupuncturists are a sadistic bunch: personality scales showed they were just as sensitive and empathetic as the control group. Instead, the researchers said their results show that rather than "responding on the basis of automatically activated stimulus-response linkages...humans regulate their emotions by relying on higher cognitive processes involving knowledge in working memory, long-term memory and meta-cognition."

The researchers said that, in the case of doctors, such emotional control was necessary for "successful professional practice", allowing medical professionals to "regulate their feelings of unpleasantness generated by the perception of pain in others."

CHENG, Y., LIN, C., LIU, H., HSU, Y., LIM, K., HUNG, D., DECETY, J. (2007). Expertise Modulates the Perception of Pain in Others. Current Biology, 17(19), 1708-1713. DOI: 10.1016/j.cub.2007.09.020

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

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