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Reducing Prejudice Through Brain Stimulation

Published:April 24, 2015DOI:https://doi.org/10.1016/j.brs.2015.04.003

      Highlights

      • Increasing cognitive control may overcome negative bias toward members of social out-groups.
      • The medial prefrontal cortex (mPFC) may contribute to self-regulatory and cognitive-control processes implemented to override social stereotypes.
      • Anodal excitability-enhancing tDCS of the mPFC decreased implicit biased attitudes toward out-group members.

      Abstract

      Background

      Social categorization and group identification are essential ingredients for maintaining a positive self-image that often lead to negative, implicit stereotypes toward members of an out-group. The medial prefrontal cortex (mPFC) may be a critical component in counteracting stereotypes activation.

      Objective

      Here, we assessed the causal role of the mPFC in these processes by non-invasive brain stimulation via transcranial direct current stimulation (tDCS).

      Method

      Participants (n = 60) were randomly and equally assigned to receive anodal, cathodal, or sham stimulation over the mPFC while performing an Implicit Association Test (IAT): They were instructed to categorize in-group and out-group names and positive and negative attributes.

      Results

      Anodal excitability-enhancing stimulation decreased implicit biased attitudes toward out-group members compared to excitability-diminishing cathodal and sham stimulation.

      Conclusions

      These results provide evidence for a critical role of the mPFC in counteracting stereotypes activation. Furthermore, our results are consistent with previous findings showing that increasing cognitive control may overcome negative bias toward members of social out-groups.

      Keywords

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      References

        • Amodio D.M.
        The neuroscience of prejudice and stereotyping.
        Nat Rev Neurosci. 2014; 15: 670-682
        • Allport G.W.
        The nature of prejudice.
        Addison Wesley Publishing Company, Reading, MA1979
        • Hogg M.A.
        • Abrams D.
        Social identifications: a social psychology of intergroup relations and group processes.
        Routledge, London1988
        • Medin D.L.
        • Smith E.E.
        Concepts and concept formation.
        Annu Rev Psychol. 1984; 35: 113-138
        • Tajfel H.
        • Turner J.C.
        An integrative theory of intergroup conflict.
        in: Austin W.G. Worchel S. The social psychology of intergroup relations. Brooks/Cole, Monterey1979: 33-47
        • Brewer M.B.
        In-group bias in the minimal intergroup situation: a cognitive motivational analysis.
        Psychol Bull. 1979; 86: 307-324
        • Tajfel H.
        • Turner J.C.
        The social identity theory of intergroup behavior.
        in: Worchel S. Austing W.G. Psychology of intergroup relations. Nelson-Hall, Chicago1986: 7-24
        • Greenwald A.G.
        • Banaji M.R.
        Implicit social cognition: attitudes self-esteem and stereotypes.
        Psychol Rev. 1995; 102: 4-27
        • Wheeler S.C.
        • Petty R.E.
        The effects of stereotype activation on behavior: a review of possible mechanisms.
        Psychol Bull. 2001; 127: 797-826
        • Dovidio J.F.
        • Kawakami K.
        • Gaertner S.L.
        Implicit and explicit prejudice and interracial interactions.
        J Pers Soc Psychol. 2002; 82: 62-68
        • Greenwald A.G.
        • Poehlman T.A.
        • Uhlmann E.
        • Banaji M.R.
        Understanding and using the Implicit Association Test: III Meta-analysis of predictive validity.
        J Pers Soc Psychol. 2009; 97: 17-41
        • Crosby F.
        • Bromley F.
        • Saxe L.
        Recent unobtrusive studies of black and white discrimination and prejudice.
        Psychol Bull. 1980; 87: 546-563
        • Ito T.A.
        • Bartholow B.D.
        The neural correlates of race.
        Trends Cogn Sci. 2009; 13: 524-531
        • Falk E.
        • Lieberman M.
        The neural bases of attitudes evaluations and behavior change.
        in: Kruger F. Grafman J. The neural basis of human belief systems. Taylor and Francis Psychology Press, London2012: 71-94
        • Devine P.G.
        Stereotypes and prejudice: their automatic and controlled components.
        J Pers Soc Psychol. 1989; 56: 5-18
        • Conrey F.R.
        • Sherman J.W.
        • Gawronski B.
        • Hugenberg K.
        • Groom C.J.
        Separating multiple processes in implicit social cognition: the quad Model of implicit task performance.
        J Pers Soc Psychol. 2005; 89: 469-487
        • Sherman J.W.
        • Gawronski B.
        • Gonsalkorale K.
        • Hugenberg K.
        • Allen T.J.
        • Groom C.J.
        The self-regulation of automatic associations and behavioral impulses.
        Psychol Rev. 2008; 115: 314-335
        • Amodio D.M.
        • Devine P.G.
        • Harmon-Jones E.
        Individual differences in the regulation of intergroup bias: the role of conflict monitoring and neural signals for control.
        J Pers Soc Psychol. 2008; 94: 60-74
        • Bartholow B.D.
        • Henry E.A.
        Response conflict and affective responses in the control and expression of race bias.
        Soc Personal Psychol Compass. 2010; 4: 871-888
        • Botvinick M.M.
        • Braver T.S.
        • Carter C.S.
        • Barch D.M.
        • Cohen J.D.
        Conflict monitoring and cognitive control.
        Psychol Rev. 2001; 108: 624-652
        • Kerns J.G.
        • Cohen J.D.
        • MacDonald A.W.
        • Cho R.Y.
        • Stenger V.A.
        • Carter C.S.
        Anterior cingulate conflict monitoring and adjustments in control.
        Science. 2004; 303: 1023-1026
        • Richeson J.A.
        • Baird A.A.
        • Gordon H.L.
        • et al.
        An fMRI examination of the impact of interracial contact on executive function.
        Nat Neurosci. 2003; 6: 1323-1328
        • Richeson J.A.
        • Shelton J.N.
        When prejudice does not pay effects of interracial contact on executive function.
        Psychol Sci. 2003; 14: 287-290
        • Payne B.K.
        Prejudice and perception: the role of automatic and controlled processes in misperceiving a weapon.
        J Pers Soc Psychol. 2001; 81: 181-192
        • Easdon C.M.
        • Vogel-Sprott M.
        Alcohol and behavioral control: impaired response inhibition and flexibility in social drinkers.
        Exp Clin Psychopharmacol. 2000; 8: 387-394
        • Hasher L.
        • Zacks R.T.
        Working memory comprehension and aging: a review and a new view.
        Psychol Learn Motiv. 1988; 22: 193-225
        • Bartholow B.D.
        • Dickter C.L.
        • Sestir M.A.
        Stereotype activation and control of race bias: cognitive control of inhibition and its impairment by alcohol.
        J Pers Soc Psychol. 2006; 90: 272-287
        • Gonsalkorale K.
        • Sherman J.W.
        • Allen T.J.
        • Klauer K.C.
        • Amodio D.M.
        Accounting for successful control of implicit racial bias the roles of association activation response monitoring and overcoming bias.
        Pers Soc Psychol Bull. 2011; 37: 1534-1545
        • van Nunspeet F.
        • Ellemers N.
        • Derks B.
        • Nieuwenhuis S.
        Moral concerns increase attention and response monitoring during IAT performance: ERP evidence.
        Soc Cogn Affect Neurosci. 2014; 9: 141-149
        • Amodio D.M.
        • Devine P.G.
        • Harmon-Jones E.
        A dynamic model of guilt: implications for motivation and self-regulation in the context of prejudice.
        Psychol Sci. 2007; 18: 524-530
        • MacDonald A.W.
        • Cohen J.D.
        • Stenger V.A.
        • Carter C.S.
        Dissociating the role of the dorsolateral prefrontal and anterior cingulate cortex in cognitive control.
        Science. 2000; 288: 1835-1838
        • Cunningham W.A.
        • Johnson M.K.
        • Raye C.L.
        • Gatenby J.C.
        • Gore J.C.
        • Banaji M.R.
        Neural components of conscious and unconscious evaluations of Black and White faces.
        Psychol Sci. 2004; 15: 806-813
        • Amodio D.M.
        • Kubota J.T.
        • Harmon-Jones E.
        • Devine P.G.
        Alternative mechanisms for regulating racial responses according to internal vs external cues.
        Soc Cogn Affect Neurosci. 2006; 1: 26-36
        • Amodio D.M.
        Coordinated roles of motivation and perception in the regulation of intergroup responses: frontal cortical asymmetry effects on the P2 event-related potential and behavior.
        J Cogn Neurosci. 2010; 22: 2609-2617
        • Stanley D.
        • Phelps E.A.
        • Banaji M.R.
        The neural basis of implicit attitudes.
        Curr Dir Psychol Sci. 2008; 17: 164-170
        • Amodio D.M.
        • Frith C.D.
        Meeting of minds: the medial frontal cortex and social cognition.
        Nat Rev Neurosci. 2006; 7: 268-277
        • Fiske S.T.
        • Ames D.L.
        • Cikara M.
        • Harris L.T.
        Scanning for scholars: how neuro-imaging the MPFC provides converging evidence for interpersonal stratification.
        in: Derks B. Scheepers D. Ellemers N. Neuroscience of prejudice and intergroup relations. Taylor and Francis Psychology Press, London2013: 89-109
        • Frith C.D.
        • Frith U.
        Interacting minds-a biological basis.
        Science. 1999; 286: 1692-1695
        • Harris L.T.
        • Fiske S.T.
        Dehumanizing the lowest of the low neuroimaging responses to extreme out-groups.
        Psychol Sci. 2006; 17: 847-853
        • Cikara M.
        • Bruneau E.G.
        • Saxe R.R.
        Us and them intergroup failures of empathy.
        Curr Dir Psychol Sci. 2011; 20: 149-153
        • Amodio D.M.
        • Ratner K.
        Mechanisms for the regulation of intergroup responses: a social neuroscience analysis.
        in: Decety J. Cacioppo J.T. Handbook of social neuroscience. Oxford University Press, New York2011: 729-741
        • Paulus W.
        Transcranial electrical stimulation (tES – tDCS; tRNS tACS) methods.
        Neuropsychol Rehabil. 2011; 21: 602-617
        • Nitsche M.A.
        • Paulus W.
        Transcranial direct current stimulation–update 2011.
        Restor Neurol Neurosci. 2011; 29: 463-492
        • Nitsche M.A.
        • Liebetanz D.
        • Lang N.
        • Antal A.
        • Tergau F.
        • Paulus W.
        Safety criteria for transcranial direct current stimulation tDCS in humans.
        Clin Neurophysiol. 2003; 114: 2220-2222
        • Nitsche M.A.
        • Cohen L.G.
        • Wassermann E.M.
        • et al.
        Transcranial direct current stimulation: State of the art 2008.
        Brain Stimul. 2008; 1: 206-223
        • Kuo M.F.
        • Nitsche M.A.
        Effects of transcranial electrical stimulation on cognition.
        Clin EEG Neurosci. 2012; 43: 192-199
        • Bellaïche L.
        • Asthana M.
        • Ehlis A.-C.
        • Polak T.
        • Herrmann M.J.
        The modulation of error processing in the medial frontal cortex by transcranial direct current stimulation.
        Neurosci J. 2013; https://doi.org/10.1155/2013/187692
        • Civai C.
        • Miniussi C.
        • Rumiati R.I.
        Medial prefrontal cortex reacts to unfairness if this damages the self: a tDCS study.
        Soc Cogn Affect Neurosci. 2014; (pii: nsu154)
        • Fregni F.
        • Orsati F.
        • Pedrosa W.
        • et al.
        Transcranial direct current stimulation of the prefrontal cortex modulates the desire for specific foods.
        Appetite. 2008; 51: 34-41
        • Boggio P.S.
        • Sultani N.
        • Fecteau S.
        • et al.
        Prefrontal cortex modulation using transcranial DC stimulation reduces alcohol craving: a double-blind sham-controlled study.
        Drug Alcohol Depend. 2008; 92: 55-60
        • Fregni F.
        • Liguori P.
        • Fecteau S.
        • Nitsche M.A.
        • Pascual-Leone A.
        • Boggio P.S.
        Cortical stimulation of the prefrontal cortex with transcranial direct current stimulation reduces cue-provoked smoking craving: a randomized sham-controlled study.
        J Clin Psychiatry. 2008; 69: 32-40
        • Greenwald A.G.
        • McGhee D.E.
        • Schwartz J.L.K.
        Measuring individual differences in implicit cognition: the implicit association test.
        J Pers Soc Psychol. 1998; 74: 1464-1480
        • De Houwer J.
        • Teige-Mocigemba S.
        • Spruyt A.
        • Moors A.
        Implicit measures: a normative analysis and review.
        Psychol Bull. 2009; 135: 347-368
        • Colzato L.S.
        • Sellaro R.
        • van den Wildenberg W.P.M.
        • Hommel B.
        tDCS of medial prefrontal cortex does not enhance interpersonal trust.
        J Psychophysiol. 2015;
        • Miranda P.D.
        • Lomarev M.
        • Hallett M.
        Modeling the current distribution during transcranial direct current stimulation.
        Clin Neurophysiol. 2006; 117: 1623-1629
        • Nitsche M.A.
        • Niehaus L.
        • Hoffmann K.T.
        • et al.
        MRI study of human brain exposed to weak direct current stimulation of the frontal cortex.
        Clin Neurophysiol. 2004; 115: 2419-2423
        • Gandiga P.C.
        • Hummel F.C.
        • Cohen L.G.
        Transcranial DC stimulation tDCS.: a tool for double-blind sham-controlled clinical studies in brain stimulation.
        Clin Neurophysiol. 2006; 117: 845-850
        • Nitsche M.A.
        • Paulus W.
        Excitability changes induced in the human motor cortex by weak transcranial direct current stimulation.
        J Physiol. 2000; 527: 633-639
        • Poreisz C.
        • Boros K.
        • Antal A.
        • Paulus W.
        Safety aspects of transcranial direct current stimulation concerning healthy subjects and patients.
        Brain Res Bull. 2007; 72: 208-214
        • Ambrus G.G.
        • Al-Moyed H.
        • Chaieb L.
        • Sarp L.
        • Antal A.
        • Paulus W.
        The fade-in–short stimulation–fade out approach to sham tDCS–reliable at 1 mA for naive and experienced subjects, but not investigators.
        Brain Stimul. 2012; 5: 499-504
        • Palm U.
        • Reisinger E.
        • Keeser D.
        • et al.
        Evaluation of sham transcranial direct current stimulation for randomized placebo-controlled clinical trials.
        Brain Stimul. 2013; 6: 690-695
        • Greenwald A.G.
        • Nosek B.A.
        • Banaji M.R.
        Understanding and using the Implicit Association Test: I. An improved scoring algorithm.
        J Pers Soc Psychol. 2003; 85: 197-216
        • Matsunaga K.
        • Nitsche M.A.
        • Tsuji S.
        • Rothwell J.C.
        Effect of transcranial DC sensorimotor cortex stimulation on somatosensory evoked potentials in humans.
        Clin Neurophysiol. 2004; 115: 456-460
        • Jacobson L.
        • Koslowsky M.
        • Lavidor M.
        Review tDCS polarity effects in motor and cognitive domains: a meta-analytical review.
        Exp Brain Res. 2012; 216: 1-10
        • Gallate J.
        • Wong C.
        • Ellwood S.
        • Chi R.
        • Snyder A.
        Noninvasive brain stimulation reduces prejudice scores on an implicit association test.
        Neuropsychology. 2011; 25: 185-192
        • Terbeck S.
        • Kahane G.
        • McTavish S.
        • Savulescu J.
        • Cowen P.J.
        • Hewstone M.
        Propranolol reduces implicit negative racial bias.
        Psychopharmacology. 2012; 222: 419-424
        • MacLeod C.M.
        Half a century of research on the Stroop effect: an integrative review.
        Psychol Bull. 1991; 109: 163-203
        • Simon J.R.
        • Small Jr., A.M.
        Processing auditory information: Interference from an irrelevant cue.
        J Appl Psychol. 1969; 53: 433-435
        • Gladwin T.E.
        • den Uyl T.E.
        • Wiers R.W.
        Anodal tDCS of dorsolateral prefontal cortex during an Implicit Association Test.
        Neurosci Lett. 2012; 517: 82-86