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A Big Brother in the brain:
neuroeconomics of social
influence on our decisionmaking
A general mechanism of social
influence on our decisionmaking
Vasily Klucharev
- University of Basel
Social influence on
Decision making
Level of complexity
biosphere
society
Economics
Social psychology
cognition
brain
neuron
gene
Cognitive &
Behavioral
neuroscience
Level of complexity
biosphere
society
cognition
brain
neuron
gene
Neuro-Economics
• Economics, psychology, and neuroscience
are converging today into a single, unified
discipline with the ultimate aim of providing
a single, general theory of human behavior neuroeconomics.
• The goal of this discipline is to understand
the processes that connect sensation and
action by revealing the neurobiological
mechanisms by which decisions are made.
Adopted from Glimcher&Rustichini, Science 2004
Solomon Asch found that the (genuine) participants conformed on 32% of
the trials and only 26% of people never conformed (1951).
What happens when our behavior is different from the
normative group behavior?
How do we
detect
own violation
of Norms?
Learning Theory
Prediction error – the discrepancy between an actually
received reward and its prediction.
Learning is proportional to the prediction error.
Dopamine response = Reward occurred – Reward predicted
Wolfram Schultz
Dopamine system
Dopamine system
Posterior Medial Frontal Cortex
=
Rostral Cingulate Zone (RCZ)
Fields et al 2007
Ventral Striatum
=
Nucleus Accumbens (NA)
Hypothesis:
Social influence triggers an
error signal using the
same neural networks that
underlie reinforcement
learning.
RCZ
Error signal
RCZ
Dopamine neurons
Error threshold
Error signal
Madonna
evolution…
Roman catacombs
IV century
Sandro BOTTICELLI
XVI century
DUCCIO di Buoninsegna
XIII century
Edvard MUNCH
XIX century
Jan van EYCK
XIII century
XX century
beauty is universal…
http://www.anticipation.info/texte/eibesfeldt/evolution.humb.univie.ac.at/electronic/faces.html
Face (S1)
2 sec
fMRI session
Attractiveness rating
Normative rating + Face (S2)
2 sec
Face (S1)
2 sec
conflict
Response
OR
conflict
OR
15-30 min later
Behavioural
session
no
conflict
Klucharev et al, Neuron 2009
Face (S1)
2 sec
Neuroimaging session
Attractiveness rating
Normative rating + Face (S2)
2 sec
conflict
Social conflict effects:
confirmatory [no conflict] vs.
conflicting group feedback
OR
conflict
OR
Conformity effect: subsequently
changed vs. unchanged ratings of
attractiveness due to group
feedback
no
conflict
Brain-scanning
Behavioral Effects: changes of attractiveness ratings
induced by normative (group) ratings.
Klucharev et.al. 2009 Neuron
Klucharev et.al. 2009 Neuron
Long-term behavioural change
evoked by expert sources
Falk et al. J. of Neuroscience (2010)
Individual tendencies to be influenced
by ��expert’’ music experts
Campbell-Meiklejohn et al Current Biology (2010)
Individual sensitivity to popularity
X effect of popularity information
G.S. Berns et al. NeuroImage (2010)
preferences for t-shirts
K. Izuma, Neuron 2013
Fields et al, 2007
TMS – Transcranial Magnetic
Stimulation
TMS
Fields et al, 2007
Design/Materials/Procedure/Subjects
• Continuous theta burst stimulation paradigm
(cTBS, Huang et al., 2005) - a 40 s train of
uninterrupted TBS (600 pulses).
Face (S1)
2 sec
Attractiveness rating
Experimental task
Normative rating + Face (S2)
2 sec
Face (S1)
2 sec
conflict
Response
OR
conflict
OR
Behavioural
session
no
conflict
17 subjects
16 subjects
17 subjects
Klucharev et.al. 2011 J Neuroscience
• Down-regulation of the pMFC suppresses subjects’
conformal behavior.
• Overall, results indicates that social conformity is
underlined by the activity of neural (dopaminergic)
circuitry involved into the reinforcement learning.
Daniel K Campbell-Meiklejohn
What is the temporal dynamic
of the neural activity?
Fields et al, 2007
Feedback Related Negativity – FRN
(analogous to ERN)
Fz
Shestakova et al 2012 (SCAN)
Fz
Shestakova et al 2013 (SCAN)
Elekta NeuromagВ® TRIUX Sensor array
MEG sensor array with 306
Superconducting QUantum
Interference Devices: “SQUID’s”
Magnetoencephalography (MEG)
FRNm, GFPm
Isofield map
*
Power
190 – 210 ms
Conflicts
No conflicts
Difference wave
*
190 – 210 мс
Time
Statistical map
* P < 0.05, FDR 0.1
Adapted from Zubarev et al.
Conflict with the group norm. Source analysis
Adapted from Zubarev et al.
46
pMFC activity
Correlation of RCZ FRNm and behavioral
performance (conformal changes)
following conflict with social norms
Conformity
47
Conclusions
пѓј social influence is underlined by the neural activity of
the dopaminergic system (Klucharev et al, 2009)
пѓј activity of the medial frontal cortex is essential for
social influence (Klucharev et al, 2011)
пѓј dopamine agonist boosts social influence
(Campbell-Meiklejohn et al, 2009)
пѓј the effect of social influence is underlined by frontomedial activity around 200-400 ms (Shestakova et
al, 2012; Shestakova et al, under preparation)
Neural �dissonance thermometer’ hypotheses
(a) The pMFC activation in response to discrepancy between one's and the group rating. Klucharev et
al.
(b) The pMFC area involved in cognitive dissonance in the induced compliance paradigm. van Veen et
al.
(c) The pMFC area activated by cognitive dissonance in the free-choice paradigm. Izuma et al..
(d) The pMFC area activated by cognitive imbalance. Izuma et al..
Keise Izuma The neural basis of social influence and attitude change Current Opinion in Neurobiology 2013
Social Influence
Valuation
Dopamine system
Decision
Option 1
Option 2
Option 3
Option 4
Option 5
�dissonance thermometer’
Wisdom of the crowd
median guess = 1207 pounds
the true weight = 1198 pounds
Sir Francis Galton
(1822 –1911)
800 farmers people participated in a contest to estimate the weight of a ox
• An evolutionarily stable strategy – a
strategy which, if most members of a
population adopt it, cannot be
bettered by an alternative strategy.
• Since each individual is trying to
maximize his own success, the only
strategy that persists in the population
will be one which, once evolved cannot
be bettered by any deviant individual.
… selection will penalize deviation
from it.
• “best strategy for an individual
depends on what the majority of the
population are doing.”
General mechanism of Social
influence
• People compare their own decisions with others’
decisions.
• Perceived difference evokes an “error” signal indicating
deviations from group normative behavior.
• This signal could then be used to adjust one’s own
decision, depending on how much weight it is given.
• Such social “error” signal could share the same neural
mechanism as the “reward prediction error” underlying
reinforcement learning.
Level of complexity
biosphere
society
cognition
brain
neuron
gene
Neuro-Economics
Many thanks to:
GuillГ©n FernГЎndez
Ale Smidts
Anna Shestakova
Alexey Ossadtchi Ivan Zubarev
Sergey Tugin
Jörg Rieskamp
Mark Rijpkema
Kaisa Hytonen
Moniek Munneke
Thank you for your attention!
No money return.
2013В©
Zaki et al. 2011 Psych. Science
Need for uniqueness (NF) - intrinsic satisfaction from the perception that
they are unique, special, and separable from the masses (Fromkin and
Snyder, 1980)
GM/WM volume (GMV/WMV), using voxel-based morphometry
Takeuchi (2012) NeuroImage
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