Why do we treat our in-group better than we do our out-group?

In-Group Bias

, explained.
Bias

What is In-Group Bias?

In-group bias (also known as in-group favoritism) is the tendency of people to give preferential treatment to others who belong to the same group as they do. This bias can show up even when people are put into groups randomly, making group membership effectively meaningless.

An illustration showing two groups of stick figures walking abstract creatures. One figure in the first group says, 'I don't trust this guy,' while pointing at the second group, illustrating in-group bias.

Where this bias occurs

Have you ever felt an instant connection with someone just because you’re part of the same group? Let’s say you’re a football fan and you root for the New England Patriots. At work, you have a couple of coworkers who are also into football: John, who is also a Patriots fan, and Julie, who supports the Philadelphia Eagles. Even though you get along with both of your coworkers equally well, you feel a closer connection to John. You find yourself chatting with him more often, backing him up in group meetings, and maybe even trusting his opinion on work projects a little more. This doesn’t necessarily mean that you dislike Julie, but rather that you favor John because the two of you share a social group.

Even small, seemingly insignificant group labels can influence how we interact with the people around us. This pattern, known as in-group bias, is well-documented across a wide range of social contexts.19 Whether it’s something as arbitrary as a favorite sports team or something more deep-rooted like our ethnic or cultural background, we often act more prosocially toward members of our own group than toward those outside our group—whether we notice it or not.

Related Biases

Sources

  1. Cadsby, C. B., Du, N., & Song, F. (2016). In-group favoritism and moral decision-making. Journal of Economic Behavior & Organization, 128, 59–71. https://doi.org/10.1016/j.jebo.2016.05.008 
  2. Gazal-Ayal, O., & Sulitzeanu-Kenan, R. (2010). Let my people go: Ethnic in-group bias in judicial decisions—Evidence from a randomized natural experiment. Journal of Empirical Legal Studies, 7(3), 403–428. https://doi.org/10.1111/j.1740-1461.2010.01183.x 
  3. Billig, M., & Tajfel, H. (1973). Social categorization and similarity in intergroup behaviour. European Journal of Social Psychology, 3(1), 27–52. https://doi.org/10.1002/ejsp.2420030103 
  4. Tajfel, H. (1982). Social psychology of intergroup relations. Annual Review of Psychology, 33(1), 1–39. https://doi.org/10.1146/annurev.ps.33.020182.000245 
  5. Kaufman, S. B. (2019, June 7). In-group favoritism is difficult to change, even when the social groups are meaningless. Scientific American. https://blogs.scientificamerican.com/beautiful-minds/in-group-favoritism-is-difficult-to-change-even-when-the-social-groups-are-meaningless/ 
  6. Hogg, M. A., Terry, D. J., & White, K. M. (1995). A tale of two theories: A critical comparison of identity theory with social identity theory. Social Psychology Quarterly, 58(4), 255–269. https://doi.org/10.2307/2787127 
  7. Golec de Zavala, A., Federico, C. M., Sedikides, C., Guerra, R., Lantos, D., Mroziński, B., Cypryańska, M., & Baran, T. (2019). Low self-esteem predicts out-group derogation via collective narcissism, but this relationship is obscured by in-group satisfaction. Journal of Personality and Social Psychology, 119(3), 741–764. https://doi.org/10.1037/pspp0000260 
  8. Yamagishi, T., Jin, N., & Miller, A. S. (1998). In-group bias and culture of collectivism. Asian Journal of Social Psychology, 1(3), 315–328. https://doi.org/10.1111/1467-839x.00020 
  9. Konnikova, M. (2012, September 5). Revisiting robbers cave: The easy spontaneity of intergroup conflict. Scientific American. https://blogs.scientificamerican.com/literally-psyched/revisiting-the-robbers-cave-the-easy-spontaneity-of-intergroup-conflict/ 
  10. Perry, G. (2014, November). The view from the boys. The Psychologist. https://thepsychologist.bps.org.uk/volume-27/edition-11/view-boys 
  11. Schnake, S., Beal, D., & Ruscher, J. (2006). Modern racism and intergroup bias in causal explanation. Race, Gender & Class, 13(1/2), 133–143. http://www.jstor.org/stable/41675227 
  12. Stagnaro, M., Dunham, Y., & Rand, D. G. (2018). Profit versus prejudice: Harnessing self-interest to reduce in-group bias. Social Psychological and Personality Science, 9(1), 50–58. https://doi.org/10.1177/1948550617699254 
  13. Gaertner, S. L., Dovidio, J. F., Rust, M. C., Nier, J. A., Banker, B. S., Ward, C. M., Mottola, G. R., & Houlette, M. (1999). Reducing intergroup bias: Elements of intergroup cooperation. Journal of Personality and Social Psychology, 76(3), 388. https://doi.org/10.1037/0022-3514.76.3.388 
  14. Rand, D. G., Pfeiffer, T., Dreber, A., Sheketoff, R. W., Wernerfelt, N. C., & Benkler, Y. (2009). Dynamic remodeling of in-group bias during the 2008 presidential election. Proceedings of the National Academy of Sciences, 106(15), 6187–6191. https://doi.org/10.1073/pnas.0811552106 
  15. Wann, D. L., & Grieve, F. G. (2005). Biased evaluations of in-group and out-group spectator behavior at sporting events: The importance of team identification and threats to social identity. The Journal of Social Psychology, 145(5), 531–546. https://doi.org/10.3200/socp.145.5.531-546 
  16. Shariatmadari, D. (2018, April 16). A real-life Lord of the Flies: the troubling legacy of the Robbers Cave experiment. The Guardian. https://www.theguardian.com/science/2018/apr/16/a-real-life-lord-of-the-flies-the-troubling-legacy-of-the-robbers-cave-experiment
  17. Sheng, F., Liu, Y., Zhou, B., Zhou, W., & Han, S. (2013). Oxytocin modulates the racial bias in neural responses to others’ suffering. Biological Psychology, 92(2), 380–386. https://doi.org/10.1016/j.biopsycho.2012.11.018 
  18. Kang, P., Burke, C. J., Tobler, P. N., & Hein, G. (2021). Why we learn less from observing outgroups. Journal of Neuroscience, 41(1), 144–152. https://doi.org/10.1523/JNEUROSCI.0926-20.2020 
  19. Everett, J. A., Faber, N. S., & Crockett, M. (2015). Preferences and beliefs in ingroup favoritism. Frontiers in Behavioral Neuroscience, 9(15), 1–21. https://doi.org/10.3389/fnbeh.2015.00015 
  20. Chae, J., Kim, K., Kim, Y., Lim, G., Kim, D., & Kim, H. (2022). Ingroup favoritism overrides fairness when resources are limited. Scientific Reports, 12(4560). https://doi.org/10.1038/s41598-022-08460-1  
  21. Corbeel, B. (2023, December 22). How Does Ingroup Bias Affect Social Cohesion and Integration? Medium. https://medium.com/@brechtcorbeel/how-does-ingroup-bias-affect-social-cohesion-and-integration-fd37172fe3fe 
  22. Marques, J. M., & Paez, D. (1994). The ‘black sheep effect’: Social categorization, rejection of ingroup deviates, and perception of group variability. European Review of Social Psychology, 5(1), 37–68. https://doi.org/10.1080/14792779543000011 
  23. Molenberghs, P. (2013). The neuroscience of in-group bias. Neuroscience & Biobehavioral Reviews, 37(8), 1530–1536. https://doi.org/10.1016/j.neubiorev.2013.06.002 
  24. Bizumic, B., Duckitt, J., Popadic, D., Dru, V., & Krauss, S. (2009). A cross‐cultural investigation into a reconceptualization of ethnocentrism. European Journal of Social Psychology, 39(6), 871–899. https://doi.org/10.1002/ejsp.589

About the Authors

A man in a blue, striped shirt smiles while standing indoors, surrounded by green plants and modern office decor.

Dan Pilat

Dan is a Co-Founder and Managing Director at The Decision Lab. He is a bestselling author of Intention - a book he wrote with Wiley on the mindful application of behavioral science in organizations. Dan has a background in organizational decision making, with a BComm in Decision & Information Systems from McGill University. He has worked on enterprise-level behavioral architecture at TD Securities and BMO Capital Markets, where he advised management on the implementation of systems processing billions of dollars per week. Driven by an appetite for the latest in technology, Dan created a course on business intelligence and lectured at McGill University, and has applied behavioral science to topics such as augmented and virtual reality.

A smiling man stands in an office, wearing a dark blazer and black shirt, with plants and glass-walled rooms in the background.

Dr. Sekoul Krastev

Dr. Sekoul Krastev is a decision scientist and Co-Founder of The Decision Lab, one of the world's leading behavioral science consultancies. His team works with large organizations—Fortune 500 companies, governments, foundations and supernationals—to apply behavioral science and decision theory for social good. He holds a PhD in neuroscience from McGill University and is currently a visiting scholar at NYU. His work has been featured in academic journals as well as in The New York Times, Forbes, and Bloomberg. He is also the author of Intention (Wiley, 2024), a bestselling book on the science of human agency. Before founding The Decision Lab, he worked at the Boston Consulting Group and Google.

About us

We are the leading applied research & innovation consultancy

Our insights are leveraged by the most ambitious organizations

Image

“

I was blown away with their application and translation of behavioral science into practice. They took a very complex ecosystem and created a series of interventions using an innovative mix of the latest research and creative client co-creation. I was so impressed at the final product they created, which was hugely comprehensive despite the large scope of the client being of the world's most far-reaching and best known consumer brands. I'm excited to see what we can create together in the future.

Heather McKee

BEHAVIORAL SCIENTIST

GLOBAL COFFEEHOUSE CHAIN PROJECT

OUR CLIENT SUCCESS

$0M

Annual Revenue Increase

By launching a behavioral science practice at the core of the organization, we helped one of the largest insurers in North America realize $30M increase in annual revenue.

0%

Increase in Monthly Users

By redesigning North America's first national digital platform for mental health, we achieved a 52% lift in monthly users and an 83% improvement on clinical assessment.

0%

Reduction In Design Time

By designing a new process and getting buy-in from the C-Suite team, we helped one of the largest smartphone manufacturers in the world reduce software design time by 75%.

0%

Reduction in Client Drop-Off

By implementing targeted nudges based on proactive interventions, we reduced drop-off rates for 450,000 clients belonging to USA's oldest debt consolidation organizations by 46%

Let's chat

Read Next

IKEA Effect

Why do we place disproportionately high value on things we helped to create?

Why do we place disproportionately high value on things we helped to create?

Learn More

Illusion of Control

Why do we think we have more control over the world than we do?

Why do we think we have more control over the world than we do?

Learn More

Illusion of Validity

Why are we overconfident in our predictions?

Why are we overconfident in our predictions?

Learn More
See All
Notes illustration

Eager to learn about how behavioral science can help your organization?

Contact us