Justice in the brain: Equity and efficiency are encoded differently

The study sought to shed light on the neurological underpinnings of moral decision-making, said Ming Hsu, a fellow at the U. of I.'s Beckman Institute and co-principal investigator.... Click here for more information.

Which is better, giving more food to a few hungry people or letting some food go to waste so that everyone gets a share" A study appearing this week in Science finds that most people choose the latter, and that the brain responds in unique ways to inefficiency and inequity.

The study, by researchers at the University of Illinois and the California Institute of Technology, used functional magnetic resonance imaging (fMRI) to scan the brains of people making a series of tough decisions about how to allocate donations to children in a Ugandan orphanage.

The researchers hoped to shed light on the neurological underpinnings of moral decision-making, said co-principal investigator Ming Hsu, a fellow at the U. of I.’s Beckman Institute for Advanced Science and Technology.

“Morality is a question of broad interest,” Hsu said. “What makes us moral, and how do we make tradeoffs in difficult situations"”

An interest in such issues kept the study subjects in the scanner, despite the pain of grappling with difficult choices, Hsu said. “Quite a few came out saying: ‘This is the worst experiment I’ve ever been in. I never want to do anything like this again!’ ”

The subjects were told that each child would start out with a monetary equivalent of 24 meals, an actual gift from the research team to the orphanage. An undetermined number of meals would have to be cut from some children’s allotments, however. The number of meals cut and the individual children who would be affected depended on how the subjects selected from options the researchers presented.

Every decision pitted efficiency (the total number of meals given) against equity (how much the burden of lost meals was shared among the children).

One could choose to take 15 meals from a single child, for example, or 13 meals from one child and five from another. In the first option the total number of meals lost would be lower. Efficiency would be preserved, but one child would bear the brunt of all the cuts. In the second option more children would share the burden of lost meals but more meals would be lost. The equity was better – but at a cost to efficiency.

“This dilemma illustrates the core issues of distributive justice, which involves tradeoffs between considerations that are at once compelling but which cannot be simultaneously satisfied,” the authors wrote.