The Social Brain
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. By means of fMRI we found that a deviation from the social norm triggers a neuronal response in mPFC 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 correlates with the individual’s tendency to conform to the opinion of the group (Klucharev et al, 2009). In a follow-up study, we found that downregulating the mPFC by means of TMS (Transcranial Magnetic Stimulation) indeed reduced the tendency to conform to the group, thus providing supporting evidence for its causal role (Klucharev et al., 2011).
In general, people tend to conform more strongly to the behaviour of the people with whom they identify (in-group members) than to the behaviour 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, and that the hormone oxytocin, implicated in a variety of social behaviours, enhances conformity especially to one’s in-group (see Stallen et al, 2012, 2013).
In another line of research, we focus on dishonesty. Dishonest behaviour, such as tax evasion, music piracy or fraud, is highly prevalent in our society and inflicts huge economic costs. Every day, we are faced with the conflict between the temptation to cheat and deceive for financial gains and maintaining a positive image of ourselves as being a ‘good person’. In this line of research, we investigate the psychological and neural underpinnings of decisions to either cheat and deceive, or to remain fair and honest. We find that particularly individual differences in the engagement of cognitive control and theory of mind drive decisions to be fair and honest (or not). For example, in one study we found that cognitive control may override an individual’s moral default, allowing honest people to cheat, whereas it enables cheaters to be honest (Speer, Smidts, Boksem, 2020). These insights contribute to a deeper understanding of individual differences in honesty and may aid in developing more targeted interventions aiming at reducing dishonesty.
In a final set of studies, we focus on arguably the opposite of dishonesty: how do people make decisions regarding charitable giving? While there are people in need all around the globe, why is it that some people and organizations receive donations and others do not? We found that including photographs of donation recipients increased charitable giving decisions by evoking positive emotional responses. This increase in giving was predicted by brain activity in a specific region associated with positive feelings and reward (i.e. the nucleus accumbens, Genevsky, Knutson, 2015).
Speer, S.P.H., Smidts A. & Boksem,M.A.S., (2020). Cognitive control increases honesty in cheaters but cheating in those who are honest. Proceedings of the National Academy of Sciences of the United States of America. 117 (32) 19080-19091. doi: 10.1073/pnas.2003480117
Speer, S.P.H., Smidts A., Boksem, M.A.S. (2020). Individual differences in (dis)honesty are represented in the brain’s functional connectivity: Robust out-of-sample prediction of cheating behavior. BioRXiv, doi:10.1101/2020.05.12.091116, preprint
Losecaat Vermeer A.B., Boksem, M.A.S., Gausterer, C., Eisenegger, C., Lamm, C. (2020). Testosterone increases risk-taking for status but not for money. PsyRXiv, doi:10.31234/osf.io/eu8jm, preprint
Speer, S.P.H., Boksem, M.A.S. (2019). A Multi-Voxel Investigation of Proposers' heterogeneity in the Ultimatum Game. Social Cognitive and Affective Neuroscience, in press.
Stallen, Mirre, Rossi, Filippo, Heijne, Amber, Smidts, Ale, De Dreu, Carsten K.W. & Sanfey, Alan G. (2018). Neurobiological Mechanisms of Responding to Injustice. Journal of Neuroscience, 38(12), 2944-2954.
Genevsky, A., Knutson, B. (2015). Neural affective mechanisms predict market-level microlending. Psychological Science, 26 (9), 1411-1422. doi: 10.1177/0956797615588467
Boksem, M.A.S., Mehta, P.H., Van den Bergh, B., van Son, V., Trautmann, S.T., Roelofs, K., Smidts, A. & Sanfey, A.G. (2013). Testosterone Inhibits Trust but Promotes Reciprocity. Psychological Science, 24 (11), 2306-2314.
Stallen, M., Smidts, A. & Sanfey, A.G. (2013). Peer influence: Neural mechanisms underlying in-group conformity. Frontiers in Human Neuroscience, 7, 1-7
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.
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.
Boksem, M.A.S. & De Cremer, D. (2010). Fairness Concerns Predict Medial Frontal Negativity Amplitude in Ultimatum Bargaining. Social Neuroscience, 5(1), 118-125.
Boksem, M.A.S., De Cremer, D. (2009). The neural basis of morality. In: D. De Cremer (Ed), Psychological Perspectives on Ethical Behavior and Decision Making, 153-166
Klucharev, V.A., Hytonen, K., Rijpkema, M., Smidts, A. & Fernandez, G. (2009). Reinforcement learning signal predicts social conformity, Neuron, 61, 140-151
Stallen, M., Smidts, A., Smit, G., Klucharev, V., Fernández, G., Rijpkema, M. (2009). Celebrities and Shoes on the Female Brain: The Neural Correlates of Product Evaluation in the Context of Fame. Journal of Economic Psychology 31 (5), 802-811
Klucharev, V., Smidts, A., & Fernandez, G. (2008). Brain mechanisms of persuasive communication: How “Expert Power” modulates memory and attitudes. Social Cognitive &
Affective Neuroscience, 3(4), 353-366
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