Is it an error to be ‘too different’!? Neurobiology of social conformity

1. Is it an error to be ‘too different’!? Neurobiology of social conformity Ale Smidtsa Co-authors: Vasily Klucharevab Kaisa Hytönenab, Mark Rijpkemab and Guillen Fernandezb Published in Neuron (2009), 140-151 a – Rotterdam School of Management, Erasmus University b – Donders Institute for Brain, Cognition and Behaviour, Nijmegen 21-23 August 2009 Summer Workshop on Decision Science, U of Michigan

3. Social norms • Injunctive norm – perception of common (dis)approvalof a particular kind of behavior. • What you should do • Descriptive norm–particular behavior that is mostcommon in a given situation • What people actually do

4. Sheer information on others’ behavior can be very influencing Re-use of towels in hotel rooms (field experiment; Goldstein and Cialdini, 2007) • ‘Help save the environment’ 34% • ‘75% of guests who stayed in this room used their towel more than once’ 49%

7. Solomon Asch found that the (genuine) participants conformed on 32% of the trials and only 26% of people never conformed (1951).

8. Hypothesis: • A deviation from group’ behavior (i.e. a conflict with group norms) evokes activity similar to Error Related Activity in reinforcement learning. Main areas involved: • dorsal cingular cortex (RCZ) • nucleus accumbens (NAc) • midbrain

9. Error Related Negativity

11. Error Related Negativity predicts learning Cohen & Ranganath, J. Neurosci. 2007;27:371-378

12. NAc involvement in reward prediction error 2002

13. Dopamine response = Reward occurred – Reward predicted Prediction error – the discrepancy between an actually received reward and its prediction. Learning is proportional to theprediction error. Fields et al 2007

14. Experimental Questions: • Does the ‘conflict with the group’ (i.e. conflict with the group norms) evoke activity similar to Error Related Activity in dorsal cingular cortex (RCZ) and nucleus accumbens (NAc)? • Does Error Related Activity correlate with conformity (= behavioural change in the direction of the group)? Error threshold Error response

15. OR Face (S1) 2 sec fMRI session Attractiveness rating Normative rating + Face (S2) 2 sec Face (S1) 2 sec conflict Response OR conflict no conflict Behavioural session

16. Experimental Procedure Participants: 25 females (age: 18-22; two subjects were excluded due to motion artifacts, one as misbelieving the cover story). fMRI session (1.5T Sonata, Siemens): • Task: rating the physical attractiveness of faces (in total 222 faces) • Normative Group Ratings: rating of the face by average European female from Paris and Milan. Behavioral session (30 min later outside the scanner): • Task: rate again the 222 faces

17. OR Face (S1) 2 sec fMRI session Attractiveness rating Normative rating + Face (S2) 2 sec “positive” conflict Social conflict effects: confirmatory [no conflict] vs. conflicting group feedback Conformity effect: subsequently changed vs. unchanged ratings of attractiveness due to group feedback OR “negative” conflict no conflict BOLD

18. Behavioral Effects: Changes of attractiveness ratings induced by group ratings

19. ROI-analysis

24. Individual differences in conformity & NAc activity

25. Social vs. Non-social Control (Behavioral study, N = 62)

26. fMRI contrast: Social vs. Non-social Control Conformity Social conflict

28. SummaryI • the conflict with the group evokes error-activity at rostral cingulate zone (RCZ) and nucleus accumbens (NAc) • the conformity (i.e. the change of judgment due to group feedback) is correlated with the activation of the RCZ, and by the inactivation of NAc

29. Summary II • deviation from social norms triggers an immediate neural error response • social conformity complies with the principles of the reinforcement learning • individual differences in conformity could be based on a variable reward prediction error signal

30. fMRI only correlational: What about causality? • Follow-up study (in progress): rTMS modulation of social conformity Vasily Klucharev, Moniek Munneke, Ale Smidts and Guillen Fernández

31. Does a temporal inhibition of the RCZ affect subjects’ conformal behavior?

32. Off-line cTBS 40 sec Design & Procedure • Continuous Theta Burst Stimulation paradigm (cTBS) - a 40 s train of uninterrupted TBS is given (600 pulses) (Huang et al., 2005)

33. Design & Subjects Total 90 subjects(aged 19–27 years, all females): • 30 subjects: cTBS of RCZ • 30 subjects: cTBS of the precuneus region • 30 subjects: sham control (no TMS) The TMS intensity – 80% of Active motor threshold (‘foot twitching’) MANOVA (Social conflict – 3 levels as within-subject factor, TMS location/type – two/three levels as between-subjects factor)

34. How the outcomes are informative for the central issue: • Results will demonstrate that a temporal inhibition of the RCZ affects subjects’ conformal behavior. • Results will show that social conformity complies with the principles of the reinforcement learning.

35. Social Norms campaigns • High chance of success because it relies on a basic principle • But, precisely because of that: carefully craft the message to prevent boomerang effects

36. Effect of descriptive norm information on energy use Schultz et al., Psych Science (2007), Field experiment • Households received info on their own and on the average energy use in their neighborhood • HHs consuming more than average, decreased their energy use • HHs consuming less than average, increased their energy use

37. Questions & Discussion Interested in post-doc? asmidts@rsm.nl (C) Erasmus Centre for Neuroeconomics (www.erim.nl/neuroeconomics/) & Donders Institute for Brain, Cognition and Behaviour

38. Further reading • Klucharev et al. (2009), “Reinforcement signal predicts social conformity”, Neuron, 61, 140-151. • Klucharev, Smidts and Fernandez (2008), “Brain mechanisms of persuasion: How ‘expert power’ modulates memory and attitudes”, Social Cognitive and Affective Neuroscience (SCAN), 3(4), 353-366. • Stallen et al. (2009), “Celebrities and shoes on the female brain: The neural correlates of product evaluation in the context of fame”, Journal of Economic Psychology (forthcoming).