What it did correlate with was the strength of a person’s group identity. “The more an individual’s team affiliation resonated for them, the less empathy they were likely to express for members of the rival team,” he says. “Even in this contrived setting, something as inconsequential as a computer game was enough to generate a measurable gap.”

In some ways the finding was not a surprise. Evidence of the empathy gap abounds: in political discourse, across daily headlines, even in the simple act of watching a movie. “People will cry for the suffering of one main character,” Bruneau pointed out. “But then cheer for the slaughter of dozens of others.” The observation reminded me of watching “Captain Phillips” in a packed theater at Lincoln Center, of how much people applauded when the Somali pirates — whose lives back home had been portrayed as dire — were killed. They were the bad guys. Never mind that they had barely reached manhood or that their families were desperate and starving. Never mind that some were reluctant to turn to piracy in the first place.

Back in 2010, while studying Israelis and Arabs living in the Boston area, Bruneau happened upon some unexpected data. Participants in the study read short letters about the Middle East published in local newspapers and rated how reasonable they thought each opinion was, while Bruneau scanned their brains. He’d noticed that a common sticking point in regional dialogues was that each side found the other ignorant or irrational or both. Bruneau wanted to see if those perceptions could be traced to a specific part of the theory-of-mind network.

For the most part, the results were as expected. Israeli subjects were more likely to harbor anti-Arab biases and to rate Arab perspectives as unreasonable, and vice versa. And in both groups, a small region of the brain, the medial precuneus, which may be associated with the theory-of-mind network, responded more strongly when the subject was reading letters written by members of the other group. But for three subjects, the psychological and neurological tests contradicted each other. The psychological tests indicated that they held the same types of anti-Arab biases as the other Israeli subjects, but their brain scans, and their reasonableness ratings, indicated that they were able to identify with the Arab perspective nonetheless. All three of these outliers, it turned out, were Israeli peace activists. In a scatter plot of the study’s results, in which blue dots represented the Israeli subjects and red dots represented the Palestinian ones, the peace activists stood out: three specks of blue in a quadrant of red.

The sample size was too small to make any broad inferences, but it set Bruneau on a quest of sorts. In Budapest, whenever he found himself chatting with Roma activists who were not themselves Roma, he would ask them why they wanted to help. He had a hunch that if he put any of these “non-Roma Roma” in the scanner, and then compared their results with those of other Hungarians, they, too, would end up as blue dots in a sea of red. He reasoned that something somewhere in their lives had overridden their implicit biases and moved them to behave with greater empathy toward the minority group. He wanted to know what that something was. “If we could figure out how it happens,” he said, “maybe we could harness it somehow.”

Bruneau is the first to admit that this is no simple task. For all the progress that has been made in neuroscience, he says, the human brain is still an enigma. He likens the brain to a human riding an elephant: The human rider is the part we can consciously access and control, and the elephant is the subliminal rest. “We know next to nothing about how the elephant works, or how to actually steer it,” he says. “But it exerts enormous influence on our behavior.”

Psychologists have developed a battery of tests to help them glimpse this elephant. The implicit association test, or I.A.T. (sometimes referred to as the “racist test” in popular culture), evaluates subconscious biases by measuring how long it takes a person to match certain words to certain images on a computer screen. Other tests have been designed to measure dehumanization, by gauging the extent to which we attribute higher-order, human-specific emotions to groups other than our own, or how evolved we deem a given racial group to be. They’re crude tests, to be sure, especially for a scientist trained in the precision of molecular biology. But Bruneau consoles himself with the trade-off. “The answers you get with psychology may be less final, and less satisfying in a way,” he says. “But the questions you get to ask are so much bigger.”