Magazine article Science News

Brain Areas Solve Moral Dilemmas: Regions Balance Competing Interests in Ethical Judgments

Magazine article Science News

Brain Areas Solve Moral Dilemmas: Regions Balance Competing Interests in Ethical Judgments

Article excerpt

Deciding whether to kill one person to save five is a deeply disturbing brain teaser. A study in the March 26 Journal of Neuroscience describes the neural tug-of-war that occurs in such a cruel, albeit hypothetical, situation.

Cognitive neuroscientists Amitai Shenhav of Princeton University and Joshua Greene of Harvard University asked 35 people to weigh in on 48 wrenching scenarios while undergoing functional MRI brain scans. The researchers used scenarios akin to the famous trolley choice: The hypothetical dilemma forces a person to decide whether to push an innocent man to his death to stop a runaway trolley from killing five people.

This moral quandary evokes competing motivations: the urge to save the greatest number of people and the desire to avoid emotionally repellent behavior. In their experiment, the researchers separated these considerations by asking people to consider how emotionally wrenching a certain behavior would be or to consider only the greater good.

In one such dilemma, a live grenade sails into a cafe where 10 people sit. Participants were told that they could ignore the grenade, leaving the 10 people to die, or throw it onto the patio, saving the 10 people but killing a lone diner outside. When study participants considered only emotions ("Which do you feel worse about doing?"), activity increased in the left amygdala, one of a pair of almond-shaped structures deep in the brain. The more emotionally repellent an action was to participants, the more activity they had in the left amygdala, Shenhav and Greene found. The experiment couldn't pinpoint where utilitarian "greater good" considerations get made.

When people were asked to make a decision between actions considering all aspects of the moral dilemma, a different brain area seemed to step in. …

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