Moral Dilemma

To put himself ringside, Greene took MRI brain images of 41 volunteers as they responded to 60 questions, a mix raising no moral choice, like what to cook for dinner, and questions specifically designed to force participants to make agonizing choices, like whether to smother their baby to save more lives. "Sometimes, I wanted a dilemma where everyone would say it was wrong, and other cases where everyone would say that it was right," he explains of the study design. "Sometimes, I wanted a case… where some people would say that it is right and some people would say that it was wrong. I think those are really the most interesting cases because by comparing the data from people who go one way with people who go another way we can start to see what competing moral values look like in the brain."

But brain responses changed when volunteers eventually came down on different sides of the issue. Respondents who chose to hurt their baby to save the group had brain activity that spiked in the dorsolateral prefrontal cortex, and the inferior parietal cortex — both of which are associated with cognitive control. "It seems that people who end up saying, 'Well, go ahead and smother the baby,' or whatever it is in the particular example they're talking about, they exhibit more activity in the part of the brain again that's associated with cognitive processes," he explains. In those who chose not to kill the baby, Greene says, it's possible to infer that, "their response is driven by that emotional intuition."

However, he notes that all respondents initially had increased activity in the amygdala, a brain area known to regulate emotion, so that the ACC was activated, suggesting, "Indeed there is this conflict between at least one response which we think is the emotional response, and this other response that we think is the cognitive cost-benefit analysis response," Greene says.

Most likely, these results can be traced to "at least two different processes that are at work in moral judgment. We have intuitive emotional sort of responses that give us a quick sort of flash, a sense of, 'That's wrong'... and a slower, more reflective way of thinking of things, where we can conscientiously apply a moral rule or we can think about things in a more actuarial way, like an accountant adding up costs and benefits in deciding what to do."

But how does moral decision-making play out in a world where people are likely to be taught that some things — like showing too much skin in public — are morally troublesome while others are not? Greene told Discover Magazine that it's an area he plans to explore next. "In some countries it's considered very much wrong for a woman to walk down the street with her hair exposed, whereas here we consider that fine," he says. "So, we know there's behavioral difference and anywhere that there's a behavioral difference there's got to be some kind of difference in the brain because the brain is what causes behavior. The question is not whether there are differences but what kind of a difference is it and can we see it with the technology we have?"

Ultimately, Greene hopes that the information he records will prove that our moral thinking is a convoluted mess of emotion and reason and biology, shaped by experiences that could be keeping us from reaching moral consensus. If Greene can find a new way to help us think differently about moral choice he says it could lead to life in a more peaceful world.