This was a bad experiment, because it assumes that "pain" and "pleasure" centers can be located, and that they are in the same place for men and women. It would be better to have a behaviorist experiment. The subject gets a mild shock, and is told X did it. At various times, the subject is given an opportunity to safely retaliate against X with a similar shock.
I agree. There were too many variables that weren't addressed or taken into account--at least by what was disclosed in the article.
I disagree. Between the functional M.R.I., which was used in this study and detects deoxyhemoglobin, i.e. deoxygenated hemoglobin, in parts of the brain undergoing greater metabolism, and PET scans, there's a much greater appreciation of the brain's anatomy and physiology these days.
When Bad People Are Punished, Men Smile (but Women Don't)
The study is part of a growing body of research that is attempting to better understand behavior and emotions by observing simultaneous physiological changes in the brain, a feat now attainable through imaging.
"Imaging is still in its early days but we are transitioning from a descriptive to a more mechanistic type of study," said Dr. Klaas Enno Stephan, a co-author of the paper.
Dr. Singer's team was simply trying to see if the study subjects' degree of empathy correlated with how much they liked or disliked the person being punished. They had not set out to look into sex differences.
To cultivate personal likes and dislikes in their 32 volunteers, they asked them to play an elaborate money strategy game, where both members of a pair would profit if both behaved cooperatively. The ranks of volunteers were infiltrated by actors told to play selfishly.
Volunteers came quickly to "very much like" the partners who were cooperative, while disliking those who hoarded rewards, Dr. Stephan said.
Effectively conditioned to like and dislike their game-playing partners, the 32 subjects were placed in scanners and asked to watch the various partners receive electrical shocks.
On scans, both men and women seemed to feel the pain of partners they liked. But the real surprise came during scans when the subjects viewed the partners they disliked being shocked. "When women saw the shock, they still had an empathetic response, even though it was reduced," Dr. Stephan said. "The men had none at all."
Furthermore, researchers found that the brain's pleasure centers lit up in males when just punishment was meted out.
The researchers cautioned that it was not clear if men and women are born with divergent responses to revenge or if their social experiences generate the responses.
Dr. Singer said larger studies were needed to see if differing responses would be seen in cases involving revenge that did not involve pain. Still, she added, "This investigation would seem to indicate there is a predominant role for men in maintaining justice and issuing punishment."