You arrive at the hill early, eager to cheer the cyclists racing past. the sun is bright, the people on both sides of the road are in high spirits, and speculation about the race passes through the crowd in waves. A hot dog vendor has positioned his cart up the hill, and the aroma of simmering meat wafts by, summoning your best memories of summer. Suddenly shouts erupt. The racers are approaching. You lean forward and see a blur of colors at the summit. Then you notice something wrong. The hot dog vendor has stepped away to make change, and someone has jostled his cart off its moorings. It is rolling downhill toward the road, gathering speed, and poised to kill dozens of cyclists unless someone shoves the cart across the road—but that would kill three spectators instead. What should one do?
When researchers presented this nightmarish dilemma to volunteers participating in an innovative neuropsychology study of morality at Harvard’s Moral Cognition Lab last year, the responses were evenly split. After moments of mental calculus, half the participants said the most moral decision was to push the cart into the bystanders; the other half disagreed, saying that killing for any reason was wrong, even if it meant saving more lives in the end.
One day last year, cognitive scientists Joshua Greene and Fiery Cushman, who designed the study, pulled up a series of brain scans taken as volunteers resolved the dilemma while inside an MRI machine. The scans were all marked by ghostly yellow blobs indicating areas of increased blood oxygen levels at the moment of judgment, Cushman explained. All decision-making takes mental energy, so no surprise there. More intriguing were the scans from the volunteers who opted to save more lives. These showed noticeably brighter regions of yellow, suggesting that their decisions demanded significantly more brain power. To Greene and Cushman, it appeared that reason was overriding an automatic, instinctual response.
“You have these gut reactions and they feel authoritative, like the voice of God or your conscience,” Greene says. But these powerful instincts are not commands from a higher power, they are just emotions hardwired into the brain. Our first reaction under pressure—the default response—is to go with our gut. It takes more time and far more brain power to reason the situation out.
“The reason we feel caught in moral dilemmas is that truly, our brain has two different solutions to the problem,” Cushman says. “Those processes can conflict because the brain is at war with itself.”
