Here’s an experiment. Describe the following scenario to a group of subjects. You are standing on a bridge overlooking train tracks. Five people are trapped on the tracks below you, and a train is barreling down the tracks toward them and will surely kill these people if it strikes them. Next to you is a switch that can divert the train to an alternate route and save the five people. However, one person is trapped on the alternate route, and is equally certain to be killed if you switch the train to the alternate route. What do you do?

Most people will consider for a moment or two, and then say they will flip the switch, saving five people at the expense of one. Sociopaths and non-sociopaths come to this conclusion at about the same rate and with about the same speed.

Now change the scenario slightly. Suppose instead there is just one track, but five people are still facing certain death from a train heading toward them. Now, however, there is another person standing next to you on the bridge, a large person. In fact, the person is so large that if you throw them off the bridge, they will stop train. They will die, of course, but you’ll save five people at the expense of one.

Most people take a bit longer with the second scenario and then say they would not throw the person standing next them off the bridge. That was certainly my reaction when I first read this scenario. Sociopaths, however, take about as long with the second scenario as the first, and then decide to throw their neighbor off the bridge.

So, what’s going on here? Superficially, these two scenarios are the same, right? In both cases, sociopaths calculate it’s better for one person to die than for five, and they act accordingly. But most people would see these two situations as different and act accordingly.

These two scenarios appear in the most recent issue of Scientific American. The author of the article cites research that suggests a couple of things are going on. The first scenario creates distance between us and the potential victims of our decision: we’re on a bridge, they’re on the tracks. They are “different” from us. This causes a more intellectual kind of decision-making, involving the cerebral cortex, and a deliberate calculation.

The second scenario keeps the five potential victims at a distance, but the other potential victim is standing right beside us, in our emotional space. That triggers a different brain area, the amygdala, and causes a different, more emotional, calculation to take place. In most people, this leads to a different decision.

Neuroscience confirms this hypothesis. Brain scans show that in almost everyone, sociopath or not, the cerebral cortex lights up for scenario one. In scenario two, for most people the fireworks happen in the amygdala. But for sociopaths, the amygdala stays dark in scenario two and the cerbral cortex lights up just like in scenario one.

The amygdala, sometimes denigrated as our “lizard brain,” is the center of emotion, including empathy. For sociopaths, there seems to be a difference in the amygdala, whether in function, magnitude or something else no one knows, that suppresses the empathic response. In extreme cases, you get Hannibal Lector, who can’t connect at all. In less extreme cases, you might get the hedge fund manager mentioned in the full article who says “insensitivity” is one of the three traits, along with focus and intellect, that most contributes to his success. Really? Insensitivity? And you’re proud of that and mention it in an interview?

Even worse, there’s another article in the same issue about how people choose leaders. Researchers showed subjects photographs of candidates for governor in the 2010 cycle and asked them to choose the candidate who looked most capable. Subjects had nothing else on which to base their choice than appearance: no policy statements, no “character” stories.” Nothing. In over two thirds of the actual elections, the one who looked most capable won.

That’s terrifying.

That means that for most people, the actual policies and positions of the candidates don’t seem to matter. I’m old enough to just barely remember the 1960 debates between JFK and Nixon. People who watched the debates on TV thought Kennedy won, while those who listened on the radio thought Nixon won. Now, more than physical appearance counts in this case. The differences in voice and accent are more pronounced on radio, while differences in physical appearance are more pronounced on TV, so it’s not correct to conclude that Nixon “won” on the issues. But it does suggest that appearances matter, whether visual or auditory. They matter a lot, if this research is to be believed.

That same lizard brain, the amygdala, is probably at work when people make decisions on a candidate’s appearance rather than policies. Emotions rather than intellect seem to govern us more than we’d probably like to admit.

What are the implications for political discourse? Well, reconsider the two scenarios. Let’s look at them in a slightly different way. The sociopath sacrifices his neighbor instead of himself. It would never occur to the sociopath to throw himself off the bridge, or to throw both himself and his neighbor off the bridge. The sociopath makes an essentially selfish choice, and most of us would agree that’s wrong. If he jumped off the bridge to stop the train with his own body, he’d be a hero, but that’s not what he did.

The two scenarios set up two populations: “us,” standing on the bridge, and “them,” on the tracks. Most of us will treat the population we belong to fairly, but are more ruthless and uncaring about exogenous populations. That’s one reason we’re reluctant to throw our neighbor off the bridge: he’s one of us. That’s also exactly why divisive politics are so destructive of the body politic: they shred the sense of belonging, of community, which is the necessary basis for successful human organizations. Successful coalitions are broad, where people see not only a shared interest but a shared sense of membership. Whether it’s possible to build such a coalition in the US today remains to be seen.

I’d have to say I think it would be impossible to build successful, cohesive communities under a system that assigns the highest moral value to selfishness. But then I don’t claim to be a fountainhead of wisdom. I’m just a math guy.

The Prisoner’s Dilemma from game theory also could illuminate this discussion. Moreover, simulations of the role of cooperation versus competition in evolution suggest that cooperation might actually be more important than competition in the long-term. But that’s for another blog.