BEHAVIOR
July 24, 2015

Altruism Simplified

Which takes more time — deciding to be generous or selfish? Brain scans tell the story.

Scientists may have been making altruism — doing for others — unnecessarily complicated. One team of researchers now suggests that simply thinking about others is the key to altruistic behavior.

Altruism involves helping others at a cost to yourself. Academics and scientists have long argued about why people act altruistically. One major school of thought holds that people are innately selfish and that acting altruistically requires self-control to override their naturally greedy tendencies. Another school holds that people are naturally generous (the bystander who runs into the burning building to save someone calling for help) and only act selfishly when they pause to think about it.

Some parts of the brain were more active during generous decisions, others were more active during selfish ones.

Cendri Hutcherson, director of the Decision Neuroscience Lab at the University of Toronto, is lead author of a new study examining altruism. She thinks that the reasons why people act altruistically are much simpler.

“We find that what matters is not whether you can exert self-control, but simply how strongly you consider others' needs relative to your own,” she says. “If you consider the other person's needs more, being generous feels easy. If you consider yourself more, generosity requires a lot of effort.”

Researchers looked at brain scans of 51 men as they played a modified version of the Dictator Game, where people are paired with a stranger and both are slated to receive some kind of cash payment. The Dictator is the one who gets to decide how to split that payment. What he decides and how he does so can offer a window into both people's selfish and generous behavior.

There were 180 trials. In each one, the Dictator was shown a pair of payments, for example $20 to himself and $85 to his partner. He could either accept these payments or reject them. If he rejected them, the default payment of $50 to each person kicked in. He was given four seconds to make his choice, which in this version had a 60:40 chance of actually being implemented, determined by a computer program.

A few seconds after making his choice, he got to see the final decision — whether his choice had been implemented or reversed. Then he moved on to the next trial.

At the end of the 180 trials, one trial was randomly picked for payout. So every time the dictator made a choice, there was a chance that the money involved was real, though he did not know which trial this would be true for. And the choices were set up so that every decision was, in monetary terms, either a selfish one or a generous one.

Functional MRI (fMRI) scans of the men's brains were conducted while the Dictator Game was playing out to get a peek at the amount of activity in different areas of the brain.

When people made generous decisions, they made them more slowly. This was especially true for the less generous people.

While some parts of the brain were more active during generous decisions, others were more active during selfish ones. But an area in the ventromedial prefrontal cortex (vmPFC) was highly active during all decisions. Hutcherson interprets this as showing a decision process resembling a cost-benefit analysis, where parts of the brain respond to self-interest and others respond to interest for others, and these are compared and weighed against each other in the vmPFC.

The scans also showed that when people made generous decisions, they made them more slowly. This was especially true for the less generous people.

Would spending more time thinking of others actually lead to kinder and more charitable behavior in real life? That sounds like something anyone who's interested in could test out on their own.

The study appears in Neuron.
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