Skip to main content Accessibility help

Can Social Contact Reduce Prejudice and Discrimination? Evidence from a Field Experiment in Nigeria


Can positive social contact between members of antagonistic groups reduce prejudice and discrimination? Despite extensive research on social contact, observational studies are difficult to interpret because prejudiced people may select out of contact with out-group members. We overcome this problem by conducting an education-based, randomized field experiment—the Urban Youth Vocational Training program (UYVT)—with 849 randomly sampled Christian and Muslim young men in riot-prone Kaduna, Nigeria. After sixteen weeks of positive intergroup social contact, we find no changes in prejudice, but heterogeneous-class subjects discriminate significantly less against out-group members than subjects in homogeneous classes. We trace this finding to increased discrimination by homogeneous-class subjects compared to non-UYVT study participants, and we highlight potentially negative consequences of in-group social contact. By focusing on skill-building instead of peace messaging, our intervention minimizes reporting bias and offers strong experimental evidence that intergroup social contact can alter behavior in constructive ways, even amid violent conflict.

Corresponding author
Alexandra Scacco is a Research Scientist, WZB Berlin Social Science Center, Reichpietschufer 50, 10785 Berlin, Germany (
Shana S. Warren is a Ph.D. Candidate, New York University, Department of Politics, 19 West 4th Street, 2nd Floor, New York, NY 10012 (
Hide All

We are grateful to Eric Arias, Kate Baldwin, Chris Blattman, Dan Butler, Eric Dickson, Pat Egan, Ryan Enos, Don Green, Macartan Humphreys, John Jost, Rebecca Littman, Noam Lupu, Gwyneth McClendon, Jack Snyder, Jonathan Weigel, Rebecca Weitz-Shapiro, and participants in the Contemporary African Political Economy Research Seminar (CAPERS), the NYU Center for Experimental Social Science, and above all to Bernd Beber, for their feedback, advice, and support. Oluwatosin Akinola and Caleb Yanet provided superb leadership in the field. Special thanks go to our dear friend Abel Adejor and to Kyauta Giwa of Community Action for Popular Participation (CAPP), and Chima Nnaedozie and microManna Ltd, our implementing partners. We thank the editor and four anonymous reviewers for helpful comments. The United States Institute of Peace (USIP) and the New York University Research Challenge Fund (URCF) provided funding for this study. This research was approved via NYU IRB Protocol 14-9985. Our pre-analysis plan is available via the Evidence in Governance and Politics (EGAP) Registry, ID 20150617AA. All errors and omissions are our own. Replication files are available on the American Political Science Review Dataverse:

Hide All
Abbink, Klaus, and Herrmann, Benedikt. 2011. “The Moral Costs of Nastiness.” Economic inquiry 49 (2): 631–3.
Abbink, Klaus, and Sadrieh, Abdolkarim. 2009. “The Pleasure of Being Nasty.” Economics Letters 105 (3): 306–8.
Abdu, Hussaini, and Umar, Lydia. 2002. “Hope Betrayed: A Report on Impunity and State-Sponsored Violence in Nigeria.” World Organization Against Torture and Center for Law Enforcement Education (OMCT Report), Lagos, Nigeria.
Acemoglu, Daron, and Wolitzky, Alexander. 2014. “Cycles of Conflict: An Economic Model.” The American Economic Review 104 (4): 1350–67.
Ahmed, Ali M., and Hammarstedt, Mats. 2008. “Discrimination in the Rental Housing Market: A Field Experiment on the Internet.” Journal of Urban Economics 64 (2): 362–72.
Alexander, Marcus, and Christia, Fotini. 2011. “Context Modularity of Human Altruism.” Science 334 (6061): 1392–94.
Allport, Gordon Willard. 1954. The Nature of Prejudice. Reading, MA: Addison-Wesley.
Amir, Yehuda. 1969. “Contact Hypothesis in Ethnic Relations.” Psychological Bulletin 71 (5): 319–42.
Angerbrandt, Henrik. 2011. “Political Decentralisation and Conflict: The Sharia Crisis in Kaduna, Nigeria.” Journal of Contemporary African Studies 29 (1): 1531.
Barnhardt, Sharon. 2009. “Near and Dear? Evaluating the Impact of Neighbor Diversity on Inter-Religious Attitudes.” Unpublished working paper.
Bar-Tal, Daniel. 1997. “Formation and Change of Ethnic and National Stereotypes: An Integrative Model.” International Journal of Intercultural Relations 21 (4): 491523.
Bar-Tal, D., and Avrahamzon, T.. 2016. “Development of Delegitimization and Animosity in the Context of Intractable Conflict.” In Cambridge Handbook of the Psychology of Prejudice, eds. Sibley, C. G., and Barlow, F. K.. Cambridge: Cambridge University Press, 582606.
Beber, Bernd, Roessler, Philip, and Scacco, Alexandra. 2014. “Intergroup Violence and Political Attitudes: Evidence from a Dividing Sudan.” The Journal of Politics 76 (3): 649–65.
Bem, Daryl J. 1972. “Self-Perception Theory.” Advances in Experimental Social Psychology 6: 162.
Bertrand, Marianne, and Mullainathan, Sendhil. 2004. “Are Emily and Brendan More Employable than Latoya and Tyrone? Evidence on Racial Discrimination in the Labor Market from a Large Randomized Experiment.” American Economic Review 94 (4): 9911013.
Bhavnani, Ravi, Donnay, Karsten, Miodownik, Dan, Mor, Maayan, and Helbing, Dirk. 2014. “Group Segregation and Urban Violence.” American Journal of Political Science 58 (1): 226–45.
Bigler, Rebecca S., and Liben, Lynn S. 2007. “Developmental Intergroup Theory Explaining and Reducing Children’s Social Stereotyping and Prejudice.” Current Directions in Psychological Science 16 (3): 162–6.
Bilali, Rezarta, and Staub, Ervin. 2016. “Interventions in Real World Settings. Using Media to Overcome Prejudice and Promote Intergroup Reconciliation in Central Africa.” In Cambridge Handbook of the Psychology of Prejudice, eds. Sibley, C. G., and Barlow, F. K.. Cambridge: Cambridge University Press, 607–31.
Brewer, Marilynn B. 1999. “The Psychology of Prejudice: Ingroup Love and Outgroup Hate?Journal of Social Issues 55 (3): 429–44.
Brown, Rupert. 2011. Prejudice: Its Social Psychology. New York: John Wiley & Sons.
Burns, Justine, Corno, Lucia, and La Ferrara, Eliana. 2015. “Interaction, Prejudice and Performance: Evidence from South Africa.” Unpublished working paper.
Camerer, Colin. 2003. Behavioral Game Theory: Experiments in Strategic Interaction. Princeton, NJ: Princeton University Press.
Cárdenas, Alexander. 2013. “Peace Building through Sport? An Introduction to Sport for Development and Peace.” Journal of Conflictology 4 (1): 2433.
Carrell, Scott E., Hoekstra, Mark, and West, James E.. 2015. The Impact of Intergroup Contact on Racial Attitudes and Revealed Preferences. Technical report. National Bureau of Economic Research. Working Paper 20940.
Cehajic, Sabina, Brown, Rupert, and Castano, Emanuele. 2008. “Forgive and Forget? Antecedents and Consequences of Intergroup Forgiveness in Bosnia and Herzegovina.” Political Psychology 29 (3): 351–67.
Devine, Patricia G. 1989. “Stereotypes and Prejudice: Their Automatic and Controlled Components.” Journal of Personality and Social Psychologyocial Psychology 56 (1): 5–18.
Devine, Patricia G., Plant, E. Ashby, Amodio, David M., Harmon-Jones, Eddie, and Vance, Stephanie L.. 2002. “The Regulation of Explicit and Implicit Race Bias: the Role of Motivations to Respond without Prejudice.” Journal of Personality and Social Psychology 82 (5): 835–48.
De Waal, Alex. 2005. “Who Are the Darfurians? Arab and African Identities, Violence and External Engagement.” African Affairs 104 (415): 181205.
Dixon, John, Durrheim, Kevin, Tredoux, Colin, Tropp, Linda, Clack, Beverley, and Eaton, Liberty. 2010. “A Paradox of Integration? Interracial Contact, Prejudice Reduction, and Perceptions of Racial Discrimination.” Journal of Social Issues 66 (2): 401–16.
Enos, Ryan D. 2016. “What the Demolition of Public Housing Teaches Us about the Impact of Racial Threat on Political Behavior.” American Journal of Political Science 60 (1): 123–42.
Enos, Ryan D., and Gidron, Noam. 2016. “Intergroup Behavioral Strategies as Contextually Determined: Experimental Evidence from Israel.” The Journal of Politics 78 (3): 851–67.
Falola, Toyin. 1998. Violence in Nigeria: The Crisis of Religious Politics and Secular Ideologies. Rochester, NY: University of Rochester Press.
Fazio, Russell H. 1987. Self-perception Theory: A Current Perspective. In Social Influence: the Ontario Symposium. Vol. 5. eds. Olson, James M., Zanna, Mark P., Herman, C. Peter; Hillsdale: Lawrence Erlbaum Associates, Inc., 129–50.
Fearon, James D., and Laitin, David D.. 2000. “Violence and the Social Construction of Ethnic Identity.” International Organization 54 (4): 845–77.
Fershtman, Chaim, and Gneezy, Uri. 2001. “Discrimination in a Segmented Society: An Experimental Approach.” Quarterly Journal of Economics 116 (1): 351377.
Fiske, Susan T. 1989. “Examining the Role of Intent: Toward Understanding Its Role in Stereotyping and Prejudice.” In Unintended Thought, Vol. 253, eds. Uleman, J. S., and Bargh, J. A.. New York: Guilford Press, 283.
Fiske, Susan T. 2000. “Stereotyping, Prejudice, and Discrimination at the Seam between the Centuries: Evolution, Culture, Mind, and Brain.” European Journal of Social Psychology 30 (3): 299322.
Gambrell, Jon. 2012. “Suicide Car Bombing Kills 38 in Nigeria on Easter Sunday.” Associated Press, April 9.
Gasser, Patrick K., and Levinsen, Anders. 2004. “Breaking Post-War Ice: Open Fun Football Schools in Bosnia and Herzegovina.” Sport in Society 7 (3): 457–72.
Gerber, Alan S., and Green, Donald P.. 2012. Field Experiments: Design, Analysis, and Interpretation. New York: WW Norton.
Gibson, James L. 2004. “Does Truth Lead to Reconciliation? Testing the Causal Assumptions of the South African Truth and Reconciliation Process.” American Journal of Political Science 48 (2): 201–17.
Gibson, James L., and Claassen, Christopher. 2010. “Racial Reconciliation in South Africa: Interracial Contact and Changes over Time.” Journal of Social Issues 66 (2): 255–72.
Gilligan, Michael J., Pasquale, Benjamin J., and Samii, Cyrus. 2014. “Civil War and Social Cohesion: Lab-in-the-Field Evidence from Nepal.” American Journal of Political Science 58 (3): 604–19.
Glaeser, Edward L. 2005. “The Political Economy of Hatred.” The Quarterly Journal of Economics 120 (1): 4586.
Green, Donald P., and Seher, Rachel L.. 2003. “What Role Does Prejudice Play in Ethnic Conflict?Annual Review of Political Science 6 (1): 509–31.
Green, Donald P., and Wong, Janelle S.. 2008. “Tolerance and the Contact Hypothesis: A Field Experiment.” In The Political Psychology of Democratic Citizenship, eds. Borgida, Eugene, Federico, Christopher M. and Sullivan, John L.. London: Oxford University Press, 228–46.
Greenwald, Anthony G., and Pettigrew, Thomas F. 2014. “With Malice Toward None and Charity for Some: Ingroup Favoritism Enables Discrimination.” American Psychologist 69 (7): 669–84.
Habyarimana, James, Humphreys, Macartan, Posner, Daniel N., and Weinstein, Jeremy M.. 2007. “Why Does Ethnic Diversity Undermine Public Goods Provision?American Political Science Review 101 (04): 709–25.
Hainmueller, Jens, and Hangartner, Dominik. 2013. “Who Gets a Swiss Passport? A Natural Experiment in Immigrant Discrimination.” American Political Science Review 107 (1): 159–87.
Hewstone, Miles, Cairns, Ed, Voci, Alberto, Hamberger, Juergen, and Niens, Ulrike. 2006. “Intergroup Contact, Forgiveness, and Experience of ‘The Troubles’ in Northern Ireland.” Journal of Social Issues 62 (1): 99120.
Jibrin, Ibrahim. 1991. “Religion and Political Turbulence in Nigeria.” The Journal of Modern African Studies 29 (1): 115–36.
Iyengar, Shanto, and Westwood, Sean J.. 2015. “Fear and Loathing across Party Lines: New Evidence on Group Polarization.” American Journal of Political Science 59 (3): 690707.
Kaas, Leo, and Manger, Christian. 2012. “Ethnic Discrimination in Germany’s Labour Market: A Field Experiment.” German Economic Review 13 (1): 120.
Kasara, Kimuli. 2013. “Separate and Suspicious: the Social Environment and Inter-Ethnic Trust in Kenya.” The Journal of Politics 75 (4): 921–36.
Kaufmann, Chaim. 1996. “Possible and Impossible Solutions to Ethnic Civil Wars.” International Security 20 (4): 136–75.
Kopstein, Jeffrey S., and Wittenberg, Jason. 2009. “Does Familiarity Breed Contempt? Interethnic Contact and Support for Illiberal Parties.” The Journal of Politics 71 (2): 414–28.
Krosnick, Jon A., and Alwin, Duane F.. 1989. “Aging and Susceptibility to Attitude Change.” Journal of Personality and Social Psychology 57 (3): 416–25.
Kunovich, Robert M., and Hodson, Randy. 2002. “Ethnic Diversity, Segregation, and Inequality: A Structural Model of Ethnic Prejudice in Bosnia and Croatia.” The Sociological Quarterly 43 (2): 185212.
Kuriansky, Judith, ed. 2007. Beyond Bullets and Bombs: Grassroots Peacebuilding between Israelis and Palestinians. Westport, CT: Greenwood Publishing Group.
Lewis, Peter. 2007. “Identity, Institutions and Democracy in Nigeria.” Afrobarometer Working Paper No.68.
Lewis, Peter, and Bratton, Michael. 2000. Attitudes Toward Democracy and Markets in Nigeria: Report of a National Opinion Survey; January-February 2000. Internat. Foundation for Election Systems.
Madu, Augustine, and Brock, Joe. 2012. “Nigerian Christian Worship Subdued by Church Bombs.” Reuters, June 24.
Malhotra, Deepak, and Liyanage, Sumanasiri. 2005. “Long-Term Effects of Peace Workshops in Protracted Conflicts.” Journal of Conflict Resolution 49 (6): 908–24.
Maoz, Ifat. 2000. “An Experiment in Peace: Reconciliation-Aimed Workshops of Jewish-Israeli and Palestinian Youth.” Journal of Peace Research 37 (6): 721–36.
McCauley, Clark. 2002. “Head First versus Feet First in Peace Education.” In Peace Education: The Concept, Principles, and Practices Around the World, eds. Salomon, Gavriel and Nevo, Baruch. Mahwah, NJ: Lawrence Erlbaum Associates, 247–58.
McConnell, Allen R., and Leibold, Jill M.. 2001. “Relations among the Implicit Association Test, Discriminatory Behavior, and Explicit Measures of Racial Attitudes.” Journal of Experimental Social Psychology 37 (5): 435–42.
McKenna, Joseph C. 1969. “Elements of a Nigerian Peace.” Foreign Affairs 47 (4): 668.
Michelitch, Kristin. 2015. “Does Electoral Competition Exacerbate Interethnic or Interpartisan Economic Discrimination? Evidence from a Field Experiment in Market Price Bargaining.” American Political Science Review 109 (1): 4361.
Mironova, Vera, and Whitt, Sam. 2014. “Ethnicity and Altruism After Violence: the Contact Hypothesis in Kosovo.” Journal of Experimental Political Science 1 (2): 170–80.
Nigeria National Bureau of Statistics. 2012. Nigeria Annual Abstract of Statistics. Abjuda, Nigeria: Federal Republic of Nigeria.
Okpanachi, Eyene. 2010. “Ethno-Religious Identity and Conflict in Northern Nigeria: Understanding the Dynamics of Sharia in Kaduna and Kebbi States.” IFRA-Nigeria e-Papers 07.
Paluck, Elizabeth Levy. 2009. “Reducing Intergroup Prejudice and Conflict Using the Media: A Field Experiment in Rwanda.” Journal of Personality and Social Psychology 96 (3): 574.
Paluck, Elizabeth Levy. 2010. “Is It Better Not to Talk? Group Polarization, Extended Contact, and Perspective Taking in Eastern Democratic Republic of Congo.” Personality and Social Psychology Bulletin 36 (9): 1170–85.
Paluck, Elizabeth Levy, and Green, Donald P.. 2009 a. “Deference, Dissent, and Dispute Resolution: An Experimental Intervention Using Mass Media to Change Norms and Behavior in Rwanda.” American Political Science Review 103 (4): 622–44.
Paluck, Elizabeth Levy, and Green, Donald P.. 2009 b. “Prejudice Reduction: What Works? A Review and Assessment of Research and Practice.” Annual Review of Psychology 60: 339–67.
Paluck, Elizabeth Levy, Green, Seth, and Green, Donald P.. 2018. “The Contact Hypothesis Revisited.” Behavioural Public Policy.
Pettigrew, Thomas F. 1998. “Intergroup Contact Theory.” Annual Review of Psychology 49 (1): 6585.
Pettigrew, Thomas F., and Tropp, Linda R.. 2006. “A Meta-Analytic Test of Intergroup Contact Theory.” Journal of Personality and Social Psychology 90 (5): 751.
Pettigrew, Thomas F., and Tropp, Linda R.. 2008. “How Does Intergroup Contact Reduce Prejudice? Meta-Analytic Tests of Three Mediators.” European Journal of Social Psychology 38 (6): 922–34.
Posen, Barry R. 1993. “The Security Dilemma and Ethnic Conflict.” Survival 35 (1): 2747.
Samii, Cyrus. 2013. “Perils or Promise of Ethnic Integration? Evidence from a Hard Case in Burundi.” American Political Science Review 107 (3): 558–73.
Sani, Shehu. 2007. The Killing Fields: Religious Violence in Northern Nigeria. Ibadan, Nigeria: Spectrum Books Ltd.
Scacco, Alexandra. 2016. “Anatomy of a Riot: Participation in Ethnic Violence in Nigeria.” Book manuscript, New York University.
Schofield, J. W., and Eurich-Fulcer, R.. 2001. “When and How School Desegregation Improves Intergroup Relations.” In Blackwell Handbook of Social Psychology: Intergroup Processes, eds. Brown, Rupert and Gaertner, Samuel L.. Oxford: Blackwell, 475–94.
Sears, David O. 1983. “The Person-Positivity Bias.” Journal of Personality and Social Psychology 44 (2): 233.
Semyonov, Moshe, and Glikman, Anya. 2009. “Ethnic Residential Segregation, Social Contacts, and Anti-Minority Attitudes in European Societies.” European Sociological Review 25 (6): 693708.
Shook, Natalie J., and Fazio, Russell H.. 2008. “Interracial Roommate Relationships: An Experimental Field Test of the Contact Hypothesis.” Psychological Science 19 (7): 717–23.
Stephan, W. G. 1978. “School Desegregation: An Evaluation of Predictions Made in Brown v. Board of Education.” Psychological Bulletin 85: 217–38.
Tertsakian, Carina. 2003. Nigeria: the “Miss World Riots”: Continued Impunity for Killings in Kaduna. New York: Human Rights Watch.
Tertsakian, Carina. 2005. Revenge in the Name of Religion: The Cycle of Violence in Plateau and Kano States. Vol. 17, New York: Human Rights Watch.
Turner, Rhiannon N., Hewstone, Miles, and Voci, Alberto. 2007. “Reducing Explicit and Implicit Outgroup Prejudice via Direct and Extended Contact: the Mediating Role of Self-Disclosure and Intergroup Anxiety.” Journal of Personality and Social Psychology 93 (3): 369.
Van Laar, Colette, Levin, Shana, Sinclair, Stacey, and Sidanius, Jim. 2005. “The Effect of University Roommate Contact on Ethnic Attitudes and Behavior.” Journal of Experimental Social Psychology 41 (4): 329–45.
Varshney, Ashutosh. 2003. Ethnic Conflict and Civic Life: Hindus and Muslims in India. New Haven, CT: Yale University Press.
Voigtländer, Nico, and Voth, Hans-Joachim. 2012. “Persecution Perpetuated: the Medieval Origins of Anti-Semitic Violence in Nazi Germany.” Quarterly Journal of Economics 127 (3): 1339–92.
Wapwera, Samuel Danjuma, and Gajere, Jiriko Kefas. 2017. “Ethnoreligious Urban Violence and Residential Mobility in Nigerian Cities: The Kaduna Experience.” Urban Studies Research 2017: 1–10.
Whitt, Sam, and Wilson, Rick K.. 2007. “The Dictator Game, Fairness and Ethnicity in Postwar Bosnia.” American Journal of Political Science 51 (3): 655–68.
Zizzo, Daniel John, and Oswald, Andrew J.. 2001. “Are People Willing to Pay to Reduce Others’ Incomes?Annales d’Economie et de Statistique 63/64: 3965.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

American Political Science Review
  • ISSN: 0003-0554
  • EISSN: 1537-5943
  • URL: /core/journals/american-political-science-review
Please enter your name
Please enter a valid email address
Who would you like to send this to? *
Type Description Title
Supplementary materials

Scacco and Warren supplementary material 1
Online Appendix

 PDF (2.7 MB)
2.7 MB
Supplementary materials

Scacco and Warren Dataset



Altmetric attention score

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed