Certain Types of Brain Damage Can Improve Utilitarian Moral Judgments, Research Shows

PASADENA, Calif.—Quick response! What's the best thing to do on a lifeboat with one too many people on board? Should one throw a mortally injured person overboard to ensure definite survival for everyone else, or refuse to act and ensure certain death for all individuals in the boat?

For most of us, the biggest stumbling block is the word "quick." Many of us will eventually concede that the greatest good for the greatest number of people is the only reasonable alternative, and that the injured person will have to be thrown overboard. However, we typically blanch at grim decisions involving actions that in other contexts would clearly be deemed immoral. Some people, in fact, never reach the utilitarian conclusion, saying that they would not be able to throw the injured person overboard, regardless of the final outcome.

But new research reveals that there is one type of person who can quickly reach the decision to act in the greater interest of the majority—the person who has suffered damage to an area of the brain known as the prefrontal cortex. In the current issue of the journal Nature, researchers from the California Institute of Technology, Harvard University, the University of Iowa, and the University of Southern California report that experimental tests on patients with prefrontal cortex damage reveal for the first time that emotions play an important role in feelings about what is right and wrong.

According to Ralph Adolphs, who holds joint appointments at Caltech and the University of Iowa Department of Neurology where the patients were tested, the results are important because they transfer the study of moral judgments from the realm of philosophical speculation to the realm of the experimental laboratory.

"The idea that emotions play a part in moral judgments is not new, but our study gives a stronger conclusion because it involves data from lesion subjects," says Adolphs.

The experiment was performed on six patients who have had tumors removed from the prefrontal cortex, 12 patients with other types of brain damage, and 12 healthy subjects. Each of the 30 test subjects was asked 50 questions involving moral dilemmas. Each question required a "yes" or "no" response, and the questions varied from easy nonmoral to very agonizing moral dilemmas (like throwing the person out of the lifeboat).

By significant margins, the six test subjects with prefrontal cortex damage were able to quickly arrive at the utilitarian response that saved the greater number of people. All the others had difficulty making those choices, and occasionally were unable to provide a "yes" answer even when the "no" scenario for action led to a greater number of people being injured or killed.

"These patients' judgments are different from the comparison subjects' judgments specifically for these high-conflict personal moral dilemmas," Adolphs explains. "Because of their brain damage, they have abnormal social emotions in real life, and lack a normal concern for the well-being of others. In other words, they lack empathy and compassion.

"So patients with prefrontal damage usually say it's preferable to throw the injured person overboard, and they don't have the conflict between emotion and reason that other people have."

The conclusion is that emotions indeed play a role in moral decisions, especially those involving questions of whether the end justifies the means. In short, the people with the brain damage are quickly able to "do the arithmetic" that determines who lives and who dies.

Adolphs is the Bren Professor of Psychology and Neuroscience and professor of biology. The lead authors of the study are Michael Koenigs and Liane Young, at the National Institute of Health and Harvard University, respectively. The other authors are Daniel Tranel of the University of Iowa, Fiery Cushman and Marc Hauser, both of Harvard, and Antonio Damasio, formerly of the University of Iowa and now at the University of Southern California.

The title of the paper is "Damage to the Prefrontal Cortex Increases Utilitarian Moral Judgments."