Scientists at HSE University have learned that disagreeing with the opinion of other people leaves a ‘trace’ in brain activity, which allows the brain to later adjust its opinion in favour of the majority-held point of view.
We often change our beliefs under the influence of others. This social behavior is called conformity and explains varios components of our behaviour, from voting at elections to fashion trends among teenagers.
Brain research has recently well informed about short-term effects of social influence on decision making. If our choice coincides with the point of view of the people who are important to us, this decision is reinforced in the brain’s “pleasure” centres involved in the larger dopaminergic system responsible for learning, motor activity and many other functions.
Conversely, in instances of disagreement with others, the brain signals that a ‘mistake’ has been made and triggers conformity.
However, there is little study of how social influence affects brain activity once some time has passed after we have formed an opinion and learned of the opinion held by others. HSE neuroscientists decided to study whether the opinion of others causes long-term changes in brain activity.
The scientists used magnetoencephalography (MEG), a unique method that allows you to see in detail activity of the human brain during information processing, and it has a temporal resolution higher than that of traditional fMRI.
At the beginning of the experiment, 20 female participants rated the degree to which they trusted strangers whose faces were depicted in a series of photographs. They then were informed about the collective opinion of a large group of peers on whether to trust these strangers.
Sometimes the opinion of the group contradicted the opinion of the participants, and sometimes it coincided with it. After half an hour, the subjects were asked to reassess their trust to the same strangers.
The study showed that the participants changed their opinion about a stranger under the influence of their peers in about half of the cases. In addition, changes occurred in their brain activity: scientists discovered ‘traces’ of past disagreements with peers.
When the subjects again saw the face of a stranger, after a split second, their brain signaled that last time their personal opinion did not coincide with the assessment given by their peers. Most likely, the fixation of this signal allows the brain to predict possible conflicts in the future arising from disagreements in order to avoid them, and this probably occurs subconsciously.
It is interesting that an area such as the superior parietal cortex, an area of the brain responsible for retrieving memories, is involved in coding the signal of past disagreements with the group.
It is likely that the faces of strangers, about whom the brain encountered a difference of opinion, are remembered better than others.
Thus, the opinions of others not only influence our behavior, but also cause long-term changes in the way our brains work.
Apparently, the brain not only quickly adjusts to the opinions of others, but also begins to perceive information through the eyes of the majority in order to avoid social conflicts in the future.
‘Our study shows the dramatic influence of others’s opinion on how we perceive information,’ says HSE University Professor Vasily Klucharev, one of the authors of the study.
‘It was very interesting to use modern methods of neuro-mapping and to see traces of past conflicts with the opinion of the group in the brain’s activity,’ adds Aleksei Gorin, a PhD student at HSE University. ‘The brain absorbs the opinion of others like a sponge and adjusts its functions to the opinion of its social group.’
The opinions of others can easily affect how much we value things. We investigated what happens in our brain when we agree with others about the value of an object and whether or not there is evidence, at the neural level, for social conformity through which we change object valuation.
Using functional magnetic resonance imaging we independently modeled (1) learning reviewer opinions about a piece of music, (2) reward value while receiving a token for that music, and (3) their interaction in 28 healthy adults. We show that agreement with two “expert” reviewers on music choice produces activity in a region of ventral striatum that also responds when receiving a valued object.
It is known that the magnitude of activity in the ventral striatum reflects the value of reward-predicting stimuli [1–8]. We show that social influence on the value of an object is associated with the magnitude of the ventral striatum response to receiving it. This finding provides clear evidence that social influence mediates very basic value signals in known reinforcement learning circuitry [9–12]. Influence at such a low level could contribute to rapid learning and the swift spread of values throughout a population.
General Discussion
Humans and animals use the reactions of others to help determine what is valuable: what to eat, what is dangerous, what is attractive, and (for humans) what to wear, what medicine to take, and for whom to vote—to give but a few examples. Each object, from food to parliamentary candidate, has a perceived value, which can be changed through social influence. C
onsequently, understanding how our values are changed by social influence is of considerable importance. We have shown that, when effective, the opinions of others alter a very basic mechanism of the human brain that reflects an immediate change in our values.
Social influence at such a basic level may contribute to the rapid learning and spread of values throughout a population. These values could range from the quality of food to race and gender stereotypes. In a world where not everyone is influenced to the same degree, we are also a step closer to knowing whose values have changed through social contact, and to what extent, by observing a quantifiable physiological process.
reference link: DOI: 10.1016/j.cub.2010.04.055 · Source: PubMed
Original Research: Open access.
“MEG signatures of long-term effects of agreement and disagreement with the majority” by A. Gorin, V. Klucharev, A. Ossadtchi, I. Zubarev, V. Moiseeva & A. Shestakova. Scientific Reports
