This time, they had participants play a game before the brain scan. Unbeknownst to the participants, some players in the game were actually actors working with the scientists. One actor's job was to play the game fairly, while the other actor’s job was to play in an obviously unfair way. You can guess which actor was more popular.
Then it was off to the scanner again. The real participant went inside the scanner, while the two actors sat outside. Again, shocks were delivered, and the computer screen indicated who was receiving the shock.
This time, the results depended on whether the participant was a man or a woman. Both genders had empathy-related brain activation when the fair player was in pain. However, the men had less empathy- related activation when the unfair player was shocked. What’s more, they had increased activation in reward-related brain areas when the unfair player got shocked. The men actually enjoyed it when the unfair player was in pain (“Bastard had it coming!”). After the experiment, Singer asked the men to rate their desire for revenge toward the unfair player. It turns out that amount of reward-related brain activation in men correlated with their desire for revenge. In guys at least, it seems that the response to someone else's pain depends on whether or not that person deserved it.