Emotional mechanisms of social biases and social norms
It is well-known that human decisions are strongly guided by social norms and that we are influenced by the behaviour and recommendations of relevant others (such as one’s peer group). The Erasmus Centre for Neuroeconomics was one of the first to study the neural mechanisms underlying social influence and social conformity. We hypothesized that one possibility for such a mechanism was that social norms are simply processed as rewards or punishments.
By means of fMRI we indeed found that a deviation from the social norm triggers a neuronal response in dopaminergic areas (rostral cingulate zone/pMFC and ventral striatum) similar to the ‘prediction error’ learning signal suggested by neuroscientific models of reinforcement learning. Furthermore, the amplitude of this neural error signal predicts the individual’s tendency to conform to the opinion of the group.
A follow-up study using transcranial magnetic stimulation (TMS) confirmed the critical role of the pMFC in social conformity. Disrupting the pMFC by means of TMS indeed reduced an individual’s tendency to conform to the group’s opinion. These findings provide evidence that social norms evoke conformity via a basic and automatic learning mechanism reflected in the activity of the dopaminergic regions.
In general, people tend to conform more strongly to the behavior of the people with whom they identify (in-group members) than to the behavior of less relevant others (out-group members). We found that conformity to the in-group is mediated by both positive affect as well as the cognitive capacity of perspective taking (Stallen et al. , 2013), and that the hormone oxytocin, implicated in a variety of social behaviors, enhances conformity especially to one’s in-group (Stallen et al., 2012).
- Klucharev V, Hytönen K, Rijpkema M, Smidts A, Fernández G. (2009). Reinforcement learning signal predicts social conformity. Neuron. 61(1):140-51.
- Klucharev, V., Munneke,M.A.M., Smidts, A. & Fernandez, G. (2011).Downregulation of the posterior medial frontal cortex prevents social conformity. The Journal of Neuroscience, 31 (33), 11934-11940.
- Stallen, M., De Dreu, C. K. W., Shalvi, S., Smidts, A. & Sanfey, A.G. (2012). The herding hormone: Oxytocin stimulates in-group conformity. Psychological Science, 23(11), 1288-1292.
- Stallen, M., Smidts, A. & Sanfey, A.G. (2013). Peer influence: Neural mechanisms underlying in-group conformity. Frontiers in Human Neuroscience, 7, 1-7.
International press about the project:
- CNN: article ‘Why so many minds think alike’ By Elizabeth Landau, January 15, 2009
- CNN: video ‘Why minds think alike’ (wmv, 9.54 MB) By Melissa Long and Elizabeth Landau, January 15, 2009
- Hindustan Times: 'Why we adjust our views in line with majority opinion' January 15, 2009
- Indo-Asian News Service: ‘Researchers explain why herd mentality governs most of us’ Muhammad Najeeb Report, January 16, 2009
- Science: ‘The brain’s pied piper’ By Rachel Zelkowitz, 14 January 2009
- Telegraph: ‘Mental process which explains why we follow crowds revealed’ By Richard Alleyne, January 14, 2009
- The Daily Telegraph: ‘How we train ourselves to conform’ By Richard Alleyne, January 14, 2009
- The Herald: ‘Tendency to conform that may have led to the rise of Hitler’ By John von Radowitz, January 15, 2009
- Voice of America: ‘Researchers investigate biology of social conformity’ By Jessica Berman, 15 January 2009
Dutch press about the project:
- NRC Handelsblad: 'Brein bestraft afwijkend oordeel' January 15, 2009
- De Volkskrant: ‘De meeloper zit ergens achter ons voorhoofd’ January 17, 2009
- Gelderlander: 'Aanpassen aan groepsnorm geeft hersens meer rust' January 13, 2009
- Trouw: 'Brein roept "foute boel" als we ons niet aanpassen' January 16, 2009