Brain reacts to fairness as it does to money and chocolate

April 21, 2008

The human brain responds to being treated fairly the same way it responds to winning money and eating chocolate, UCLA scientists report. Being treated fairly turns on the brain's reward circuitry.

"We may be hard-wired to treat fairness as a reward," said study co-author Matthew D. Lieberman, UCLA associate professor of psychology and a founder of social cognitive neuroscience.

"Receiving a fair offer activates the same brain circuitry as when we eat craved food, win money or see a beautiful face," said Golnaz Tabibnia, a postdoctoral scholar at the Semel Institute for Neuroscience and Human Behavior at UCLA and lead author of the study, which appears in the April issue of the journal Psychological Science.

The activated brain regions include the ventral striatum and ventromedial prefrontal cortex. Humans share the ventral striatum with rats, mice and monkeys, Tabibnia said.

"Fairness is activating the same part of the brain that responds to food in rats," she said. This is consistent with the notion that being treated fairly satisfies a basic need, she added.

In the study, subjects were asked whether they would accept or decline another person's offer to divide money in a particular way. If they declined, neither they nor the person making the offer would receive anything. Some of the offers were fair, such as receiving $5 out of $10 or $12, while others were unfair, such as receiving $5 out of $23.

"In both cases, they were being offered the same amount of money, but in one case it's fair and in the other case it's not," Tabibnia said.

Almost half the time, people agreed to accept offers of just 20 to 30 percent of the total money, but when they accepted these unfair offers, most of the brain's reward circuitry was not activated; those brain regions were activated only for the fair offers. Less than 2 percent accepted offers of 10 percent of the total money.

The study group consisted of 12 UCLA students, nine of them female, with an average age of 21. They had their brains scanned at UCLA's Ahmanson–Lovelace Brain Mapping Center. The subjects saw photographs of various people who were said to be making the offers.

"The brain's reward regions were more active when people were given a $5 offer out of $10 than when they received a $5 offer out of $23," Lieberman said. "We call this finding the 'sunny side of fairness' because it shows the rewarding experience of being treated fairly."

A region of the brain called the insula, associated with disgust, is more active when people are given insulting offers, Lieberman said.

When people accepted the insulting offers, they tended to turn on a region of the prefrontal cortex that is associated with emotion regulation, while the insula was less active.

"We're showing what happens in the brain when people swallow their pride," Tabibnia said. "The region of the brain most associated with self-control gets activated and the disgust-related region shows less of a response."

"If we can regulate our sense of insult, we can say yes to the insulting offer and accept the cash," Lieberman said. UCLA is California's largest university, with an enrollment of nearly 37,000 undergraduate and graduate students. The UCLA College of Letters and Science and the university's 11 professional schools feature renowned faculty and offer more than 300 degree programs and majors. UCLA is a national and international leader in the breadth and quality of its academic, research, health care, cultural, continuing education and athletic programs. Four alumni and five faculty have been awarded the Nobel Prize.

Source: University of California - Los Angeles

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4 comments

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superhuman
1.5 / 5 (2) Apr 21, 2008
This article is full of silly assumptions, why is receiving a $5 out of $23, unfair? If it was $5000 out of $23000 would it still be "insulting"?

Also maybe receiving more money sparked the reward and not "fairness" of the offer, how did authors control for that? Subjects decisions and brains could also be influenced by appearance of people on photos, their facial expression etc.

And what about that UCLA ad at the end??
fmfbrestel
3.3 / 5 (4) Apr 21, 2008
wow, did you read the article? I'll give you the UCLA add tacked to the end, but the rest of your concerns were directly answered in the artice.
They get the same amount of money regardless of which part of the experiment they are taking part in.
5 out of 23 is unfair because someone else (who they believe to be taking part in the study) offers to SPLIT the money between them, if they say yes, they get the money -- if they say no, no one gets money. How is this difficult to understand.
The only problem i have with they study is the sample size (12 participants, 9 female) I am sure this study will be followed up on in larger settings, but still thats pretty small.
ClarkS
2 / 5 (1) Apr 21, 2008
I think there could be some variables in the experiment. What if some of the participants do not value money as much as others and think it is fine with them as long as they still get 5 dollars. Unless the experiment is set up on the same ground that everybody value the item(could be money) equally, there could be other factors affecting the results.
superhuman
not rated yet Apr 22, 2008
Yeah they get the same cash I missed that one, but this experiment is deeply flawed nonetheless. The notion of 'fairness' is laughable. The person who has the power to veto would have to think he somehow deserves half of those money but there is absolutely no reason for him to believe that (at least based on what the article says).

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