Pain perception increases if equally suffering friend is nearby, study finds

Maybe misery doesn't love company. When physical pain is involved, having an equally suffering friend nearby just makes you feel worse, according to a study published online in the journal Current Biology.

The study was not aimed at figuring out whether we get by with a little help from our friends, but whether we catch emotions from them. It found that the stress induced by a social encounter with a stranger can block emotional contagion that otherwise is rampant between acquaintances. Even mice displayed more pain-related behaviour when they suffered beside equally miserable acquaintances, the study suggests.

"The contagion of the pain of one is adding to the pain of the other, making it bigger than it otherwise would be," said neuroscientist Jeffrey Mogil of McGill University in Montreal, Canada, lead researcher of the study. "In both species, this only works if they know each other."

For the mice, the experiments involved some simple injections and restraints. Humans had to hold a hand in a bucket of water chilled to 3.8 degrees Celsius.

Subjects rated their pain while soaking their hand, then were paired with an acquaintance or a stranger. When one of the pair was experiencing the pain, there was no change in anyone's solo rating of pain. When both were in pain, each reported a higher perception of their own pain if they were paired with someone they knew but not if they were with suffering strangers.

Mogil's lab, which had already shown a similar effect among mice, wondered whether the stress of meeting strangers had something to do with the difference in pain perceptions. The researchers measured levels of the stress-related hormone cortisol. It was higher during encounters with strangers. When they administered a drug that blocked the effects of the hormone, it effectively made strangers into friends, upping their pain ratings.

The drug was not the only thing that worked to take stress out of the equation, though. Apparently, all you need is love - or at least a few Beatles songs. Researchers made some strangers play four Beatles songs together on the video game Rock Band.