March 2014, Uta Frith
Chris and I are in our nice office in the Swan-house (Hattyuhaz). Agnes Volein, the coordinator of the Babylab has come in for a few minutes of chat.
AV: What is the paper about?
CF: The title is Activity in the Nucleus Accumbens and Amygdala Underlies Individual Differences in Prosocial and Individualistic Economic Choices
It’s about individual differences in people’s preference for fairness or otherwise. We call it their social orientation, which can be pro-social or pro-self.
UF: You have often said that you don’t believe that we are all basically selfish and constantly working hard to inhibit this tendency. Instead you think that, deep down, most of us are pro-social. Some people would say that is a charming belief, but surely naïve.
CF. Well, in this paper we present data to confirm my belief.
UF: Here is the first question for your Q&A: How did you personally become interested in this topic?
CF: A very long time ago (1969) I did my PhD on individual differences, but subsequently paid little attention to this aspect of psychology. More recently, I have been interested in social cognition and the neural mechanisms underlying social interactions. Most studies have tended to ignore individual differences. This is a shame because the functioning of human societies depends upon individual differences in order to achieve optimal division of labour.
UF: Lets go to question 2: In just a few sentences, what were the objectives of your study?
CF: Fairness is a very important concept in human society. But some people are more concerned about fairness than others.
Paul van Lange has used a questionnaire about the sharing out of money. Prosocials (~60%) prefer the money to be split evenly even if this means getting less themselves. Individualists ( ~30%) will choose the split that gives them the most money without regard for what other people get. Competitive types (10%) want to get more than others. Importantly, the behaviour on this questionnaire relates to real life behaviour. Prosocial people are more cooperative, give more money to charity and tend to vote liberal rather than conservative.
These differences seem stable, like personality traits. We wanted to explore their neural basis.
UF: Did you have a hypothesis?
CF: In a previous brain imaging study, Haruno & I found that dislike of unfairness was associated with activity in the amygdala. Since the amygdala is a relatively ‘primitive’ brain region, we suspected that this was a rapid, automatic response that did not involve much conscious reflection, and we wanted to test this idea further.
UF: How did you do measure dislike of unfairness?
CF: We gave people an ultimatum game to do in the scanner. Here an amount of money is presented, and a split is offered. The person has to make a decision to either accept or reject the offer, – and this is the ultimatum. If the answer is accept, the split goes to each person as per the original offer. If the answer is ‘reject’, neither person gets anything. We also had a version of the game, where the other person got his split even if the decision was ‘reject’, the impunity game.
A fair split is 50% of course, but most people accept less. For people strongly oriented towards fairness, the more unfair the split, the more likely their decision will be ‘reject’. Not so the pro-selfs. They take something rather than nothing. We wanted see what would happen when people were prevented from thinking too deeply about their response to fair or unfair splits. So we gave them a task that distracted them.
UF. Were you surprised by any of the findings in your study?
CF: We had expected that cognitive load would not affect the behaviour of our participants since their responses to unfair offers in the ultimatum game would be intuitive rather than reflective. Our findings showed that the cognitive load actually exaggerated the individual differences. So the prosocials became more prosocial, as shown by rejecting offers that were insultingly low. The pro-selfs became more selfish. That is they accepted even tiny offers, because something is better than nothing. They did not care about the other person getting a lot more, especially in the impunity version of the game.
UF: What was the significance of the activity you saw in the nucleus accumbens and amygdala?
CF: We believe that the activity in these ‘primitive’ brain regions reflects intuitive, rather than reflective processes in decision-making, and that it is these intuitive processes that largely determine whether a person is selfish or prosocial.
UF: So you feel confirmed in your belief that people are pro-social and basically have an aversion to unfairness?
CF: Absolutely. It goes against the widely held belief that people are basically selfish and that we need to reflect upon what we are doing to overcome our selfish urges. Our research says most of us are basically prosocial rather than selfish. Of course we can override this basic tendency. When we do that, our powers of reasoning are typically used to justify selfish behaviour.