Crossing your arms towards the center of your body confuses the brain and helps reduce the intensity of pain, according to scientists from University College London (UCL).
Findings published in the journal Pain say that the reason for the phenomenon is conflicting information between two of the brain’s maps — one for the body and one for external space.
"In everyday life you mostly use your left hand to touch things on the left side of the world, and your right hand for the right side of the world," Giandomenico Iannetti of UCL’s department of physiology, pharmacology and neuroscience, said in a statement about the research.
The brain areas that hold the map of the right body and the map of right external space are usually activated together, leading to very effective pain processing, Iannetti explained.
In the study, scientists used a laser to generate a four millisecond pin prick of "pure pain" — in other words, pain without touch — on the hands of a group of eight participants. This was then repeated with arms crossed.
Participants rated their perception of the pain intensity, and their electrical brain responses were also measured using electroencephalography (EEG). Results from both participants’ reports and the EEG showed that the perception of pain was weaker when the arms were crossed.
"Perhaps when we get hurt, we should not only ‘rub it better’ but also cross our arms," Iannetti said.