Why do we favor our existing beliefs?

The 

Confirmation Bias

, explained.
Bias

What is confirmation bias?

Confirmation bias describes our underlying tendency to notice, focus on, and give greater credence to evidence that aligns with our existing beliefs.

An illustration of two stick figures. The figure on the left, under a sun, is smiling and saying, "Did you read my paper on confirmation bias?" The figure on the right responds, "Yes, but it only proved what I already knew..." Between them is a blackboard with the Bayesian probability formula: P(A|B) = [P(B|A)P(A)] / P(B).

Where this bias occurs

Consider the following hypothetical situation: Jane is the manager of a local coffee shop. She is a firm believer in the motto, “Hard Work Equals Success.” The coffee shop, however, has seen a slump in sales over the past few months. Since Jane strongly believes that hard work is a means to success, she concludes that the dip in the coffee shop’s sales is because her staff are not working hard enough. To account for this, Jane puts several measures in place to ensure that her staff is working consistently. Consequently, she ends up spending more money by having a greater number of employees staffed on a shift, exceeding the shop’s budget and thus contributing to overall losses.

Consulting with other business owners in her area, Jane is able to identify her store’s new, less visible location as the primary cause of her sales slump. Her belief in hard work as the most important metric of success led her to mistakenly identify her employees’ lack of effort as the reason for the store’s falling revenue while ignoring evidence that pointed to the true cause: the shop’s poor location. Jane has fallen victim to confirmation bias, which caused her to notice and give greater credence to evidence that fit with her pre-existing beliefs.

As this example illustrates, our personal beliefs can weigh us down when conflicting information is present. Not only does it stop us from finding a solution, but we also may not even be able to identify the problem to begin with.

Sources

  1. Healy, P. (2016, August 18). Confirmation bias: How it affects your organization and how to overcome it. Business Insights Blog. https://online.hbs.edu/blog/post/confirmation-bias-how-it-affects-your-organization-and-how-to-overcome-it 
  2. Ling, R. (2020). Confirmation bias in the era of mobile news consumption: The social and psychological dimensions. Digital Journalism, 8(5), 596–604. https://doi.org/10.1080/21670811.2020.1766987 
  3. Hastall, M. R. (2020). Selective exposure, perception, and retention. In D. L. Merskin (Ed.), The SAGE international encyclopedia of mass media and society (Vol. 5, pp. 1537–1539). SAGE Publications, Inc. https://doi.org/10.4135/9781483375519   
  4. Schlosser, J. A. (2013). “Hope, danger’s comforter”: Thucydides, hope, politics. The Journal of Politics, 75(1), 169–182. https://doi.org/10.1017/s0022381612000941  
  5. Badcock, C. (2012, May 5). Making sense of Wason. Psychology Today. https://www.psychologytoday.com/ca/blog/the-imprinted-brain/201205/making-sense-wason  
  6. Lord, C. G., Ross, L., & Lepper, M. R. (1979). Biased assimilation and attitude polarization: The effects of prior theories on subsequently considered evidence. Journal of Personality and Social Psychology, 37(11), 2098–2109. https://doi.org/10.1037/0022-3514.37.11.2098  
  7. Pariser, E. (2012). The filter bubble: What the internet is hiding from you. Penguin Books. 
  8. Sarkis, S. A. (2023, September 28). How Cognitive Biases Impact Our Relationships. Psychology Today. https://www.psychologytoday.com/ca/blog/here-there-and-everywhere/202309/how-cognitive-biases-impact-our-relationships  
  9. Thomas, O., & Reimann, O. (2022). The bias blind spot among HR employees in hiring decisions. German Journal of Human Resource Management, 37(1), 5–22. https://doi.org/10.1177/23970022221094523 
  10. Herberger, K. (2025, May 20). Delusion Networks: Understanding and Addressing Collective Mass Delusions. Medium. https://medium.com/@beforebreakfast/delusion-networks-understanding-and-addressing-collective-mass-delusions-f3169ebfb295 
  11. The University of Texas Permian Basin. (2025) Psychology of Political Extremes: Exploring Group Polarization. UT Permian Basin. https://online.utpb.edu/about-us/articles/psychology/psychology-of-political-extremes-exploring-group-polarization/ 
  12. Nickerson, R. S. (1998). Confirmation bias: A ubiquitous phenomenon in many guises. Review of General Psychology, 2(2), 175–220. https://doi.org/10.1037/1089-2680.2.2.175 
  13. Casad, B. & Luebering, J. E. (2025, June 16). Confirmation bias. Encyclopædia Britannica. https://www.britannica.com/science/confirmation-bias 
  14. Team Taju Coaching. (2024, March 30). Understanding the Circular Reasoning Fallacy. Taju Coaching. https://www.tajucoaching.com/blog/understanding-circular-reasoning-fallacy 
  15. Baron, J. (2000). Thinking and deciding. Cambridge University Press.
  16. Guo, D., & Shing, Y. L. (2024). Linking the congruency effect in memory to confirmation bias in decision-making across the lifespan – Common roles of the medial prefrontal cortex: A selective review. European Psychologist, 29(4), 245–256. https://doi.org/10.1027/1016-9040/a000536 
  17. Snyder, M., & Cantor, N. (1979). Testing hypotheses about other people: The use of historical knowledge. Journal of Experimental Social Psychology, 15(4), 330–342. https://doi.org/10.1016/0022-1031(79)90042-8 
  18. Ruzzier, C. A., & Woo, M. D. (2023). Discrimination with inaccurate beliefs and confirmation bias. Journal of Economic Behavior & Organization, 210, 379–390. https://doi.org/10.1016/j.jebo.2023.04.018

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