Confirmation Bias

Gal Harpaz, The Open University of Israel
doctorharpaz@gmail.com

Confirmation bias is the tendency to seek, interpret, and remember information that supports existing beliefs while ignoring or minimising contradictory evidence. This bias is strongest in emotionally charged issues, desired outcomes, and deeply held beliefs. It manifests through selective information search—actively seeking only information that aligns with one’s views—biased interpretation, where ambiguous or mixed information is interpreted in a way that supports pre-existing beliefs, and memory bias, in which information confirming prior beliefs is better recalled while conflicting data is forgotten or downplayed.

Confirmation bias contributes to several cognitive and social phenomena, including attitude polarisation, where people become more extreme in their beliefs even when presented with the same evidence as others, and belief perseverance, in which individuals continue to believe something even after it has been clearly disproven. It also plays a role in the primacy effect, where early information is weighted more heavily than later evidence, and in the perception of false patterns, where individuals perceive relationships between unrelated events—for example, linking specific behaviors to group stereotypes without valid evidence.

This bias can lead to flawed decisions in everyday life, foster overconfidence, and increase resistance to corrective information. In research, it contributes to systematic errors by favoring supportive data while dismissing anomalies. On social media, algorithms amplify this bias by filtering content to match users’ preferences, creating echo chambers. The term was refined by psychologist Peter Wason, who demonstrated how individuals prefer confirming over disconfirming evidence. Unlike self-fulfilling prophecies that affect behavior, confirmation bias influences how information is processed—often automatically and unconsciously—making it difficult to recognise or overcome.

Keywords: beliefs, evidence, information

References:
Darley, J. M., & Gross, P. H. (1983). A hypothesis-confirming bias in labeling effects. Journal of Personality and Social Psychology, 44(1), 20–33. https://psycnet.apa.org/doi/10.1037/0022-3514.44.1.20
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
Plous, S. (1993), The psychology of judgement and decision making. McGraw-Hill
Wason, P. C. (1960). On the failure to eliminate hypotheses in a conceptual task. Quarterly Journal of Experimental Psychology, 12(3), 129-140. https://doi.org/10.1080/17470216008416717