But when the unfair player received painful punishments, men, at least, showed no empathy. In fact, they seemed to relish the physical punishments dealt out to their dishonest opponent.
"Surprisingly, we got gender differences that were quite remarkable," Singer said. "Women showed only the slightest reduction in empathy [toward those they disliked]. However, men showed a total absence of empathy."
The men instead showed brain activity in reward-related areas, which the authors correlate with an expressed desire for revenge.
After the study, male subjects were asked about their desire for revenge against the unfair actor. Those who admitted to strong feelings of revenge turned out to be those whose brain activity had been the highest.
Although more research is needed, the results could be a function of the penalty chosenphysical pain.
Singer and colleagues note that women may react more negatively to physical forms of punishment than men. Psychological, financial, or other punishments could have elicited a different response.
Brain Scans Don't Lie
Richard Smith, an experimental social psychologist at the University of Kentucky, said that psychological research on schadenfreude remains in its infancy.
But ideas of fairness and unfairness are generally thought to be key predictors of the emotion.
"There has been research on justice issues and also on just general like/dislike predictors [for schadenfreude]," Smith said. "Also there has been research on envy. Really, there are a lot of predictors of why you might feel happy that someone suffers.
"But justice is central, because it's a common-sense notion that if someone deserves to suffer, you might admit that you feel some satisfaction over that. You might even feel pretty good about admitting it."
Smith's own research with grad student Caitlin Powell has shown that hypocrisy is a key factor in people's perceptions of justice.
For example, people seem to enjoy when someone who lectures heavily about a moral issue is exposed for related moral transgressions.
Most scholars stress that admitting to pleasure afforded by another's suffering goes against many social norms. Because schadenfreude is an emotion that people don't like to admit, it is difficult for psychologists to study.
But the work by Singer, of the University College London, may provide a neurological road map for examining schadenfreude's many facets.
"It suggests some really exciting ways to look at these emotions without having to worry so much about how people are reporting their own emotions," Smith, the University of Kentucky psychologist, said.
"Presumably, the brain activity is not going to be under the same level of conscious control."
"I'm interested in the conditions when we feel schadenfreude when we really shouldn't, such as a possible link with envy," he added. "The challenge is to measure envy and schadenfreude.
"People don't like to admit either, and when the two get together, forget it. So this methodology is a very intriguing way to possibly get at those emotions."
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