fMRI Brain Study Reveals That the Opinions of Others Matters

The study suggests that scientists may be able to predict how much people can be influenced by the opinions of others based on the level of activity in the reward region of the brain.

In a study of 28 volunteers in the United Kingdom, Prof. Chris Frith and colleagues from the Wellcome Trust Centre for Neuroimaging at University College London (UCL; UK) in collaboration with Aarhus University (Aarhus, Denmark) examined the effect that having experts agree with an individual's opinions has on activity in their ventral striatum, the area of the brain associated with receiving rewards. Expert opinions about a piece of music generated more activity in this brain area when the subject shared the opinion. Expert opinions could also change the amount of ventral striatum reward activity that receiving the music could produce--depending on how likely the person was to change his or her mind because of those opinions.

Before the task, each volunteer was asked to provide a list of 20 songs that they liked, but did not currently own. They were asked to rate the songs on a scale of one to ten depending on how much they wanted the song (a score of ten indicating that they wanted the song very much). The study participants were then placed in a functional magnetic resonance imaging (fMRI) scanner, which records brain activity by measuring related changes in blood flow. They were shown one of the songs they had requested and one from a set of the previously unknown songs by Canadian and Scandinavian artists and were asked to indicate a preference between the two. The researchers then revealed to the volunteer which of the two songs the two experts preferred.

When the reviewers agreed with the subject's own choice, the researchers discovered that the subject's ventral striatum, the region of the brain associated with rewards, became active. Activity in this area tended to be strongest when both reviewers agreed with the subject. The researchers validated the role of the ventral striatum by randomly assigning tokens to the songs and measuring its effect on brain activity; the ventral striatum was most active when a token was awarded to a song chosen by the subject. (At the end of the task, the subject knew that they would receive the 10 songs with the most tokens.)

"We all like getting rewards and this is reflected in brain activity in the ventral striatum,” stated first author Dr. Daniel Campbell-Meiklejohn from the Centre of Functionally Integrative Neuroscience, Aarhus University, Denmark. "Our study shows that our brains respond in a similar way when others agree with us. One interpretation is that agreement with others can be as satisfying as other, more basic, rewards.”

Once out of the fMRI scanner, the study participants were asked to rate their choices of songs again. The researchers found that the majority of people had changed their opinions dependent on the experts' views. Seven people altered their opinions opposite to the reviewers--meaning, if the reviewers agreed with their choice, they tended to rate the song lower and vice versa.

However, most subjects appeared to be positively influenced--they were more likely to increase the rating of one of their songs if the reviewers also liked it and decrease the rating if the reviewers disliked it. In these subjects, the researchers found a link between activity in their ventral striatum when receiving the song as a reward and the opinions of reviewers: the more positively the song was reviewed, the greater the activity when receiving the song.

"It seems that not only are some people more influenced by the opinions of others, but by looking at activity in the brain, we can tell who those people are,” concluded Prof. Frith.

The study was published June 17, 2010, in the journal Current Biology.

Related Links:
Wellcome Trust Centre for Neuroimaging at University College London