McGill, 'The secret of empathy', http://www.mcgill.ca/newsroom/channels/news/secret-empathy-241112, McGill News (15 JAN 2015).
Friends and strangers
Student participants were asked to submerge their arm in ice-cold water and rate their pain. These pain scores remained the same whether they experienced the pain alone or sitting across from a stranger. However, the pain actually increased when these students put their arms in ice water across from a friend.
It's in fact a sign that there is strong empathy between individuals - they are indeed feeling each other's pain.
The researchers (…) investigated what prevented empathy between strangers and found the same cause in both humans and mice: the stress of being near a stranger.
It turns out that even a shared experience that is as superficial as playing a video game together can move people from the 'stranger zone' to the 'friend zone' and generate meaningful levels of empathy.
Loren J. Martin, Georgia Hathaway, Kelsey Isbester, Sara Mirali, Erinn L. Acland, Nils Niederstrasser, Peter M. Slepian, Zina Trost, Jennifer A. Bartz, Robert M. Sapolsky, Wendy F. Sternberg, Daniel J. Levitin, Jeffrey S. Mogil, 'Reducing Social Stress Elicits Emotional Contagion of Pain in Mouse and Human Strangers', Current Biology, DOI: http://dx.doi.org/10.1016/j.cub.2014.11.028, January 15 2015 .
Het artikel in McGill News is hier te vinden en het wetenschappelijke artikel in Current Biology is hier te vinden.