Ever flinch at the sight of an actor being punched in the face? The reason is that neurons in the brain light up when we watch others suffering. Now a team of psychologists has added evidence to the theory that such mirror systems in our brains are what lie behind our ability to empathize with others.
The conclusions are based on a rare group of individuals who feel a touch upon their own bodies when they see someone else being touched. Only one such case of mirror-touch synesthesia had been reported previously in the literature; University College London's Michael Banissy and Jamie Ward investigated the phenomenon in 10 other individuals.
In the new study, the researchers first established that the subjects had mirror-touch synesthesia. They had the individuals and members of a control group report where they felt a touch on their bodies while observing another person being touched. During the task, an actual touch was applied to their bodies as well--either at the same location as the person being observed or at a different location. The researchers found that mirror-touch synesthetes were quicker at detecting actual touch when it was applied to the same location as that of the person they were watching. They were also more likely than control subjects to report a synesthetic touch as a real touch.
In a second part of the study, subjects filled out a questionnaire designed to measure empathy. The synesthetes had a greater sense of emotional connectedness to others than nonsynesthetic participants had. These individuals also felt more connected to others than did participants with other kinds of synesthesia, such as synesthetes who perceive letters as inherently colored (ScienceNOW, 24 March 2005).
The findings, reported online in Nature Neuroscience on 17 June, suggest that feelings of empathy are driven at least in part by a mental simulation of what others are going through. "This may be an exaggeration of a brain mechanism that we all possess to some degree," says Ward.
The work is a remarkable example of "a purely mental personality trait being correlated with a basic physical sensation," says Vilayanur Ramachandran, a neuroscientist at the University of California, San Diego, and a pioneer in the study of mirror neurons. "It suggests that mirroring may be a general mechanism involved in regulating emotional behavior."