vahvistusharhaa

Vahvistusharha, or confirmation bias, is a cognitive bias in which individuals favor information that confirms their preconceptions and dismiss or downplay information that contradicts them. It affects the way people search for, interpret, and remember information.

It manifests in several ways: selective exposure to sources that align with one’s views; biased interpretation of ambiguous evidence in a way that supports existing beliefs; and memory recall that privileges confirming evidence while forgetting disconfirming data. It often accompanies motivated reasoning and efforts to reduce cognitive dissonance.

In everyday life and public discourse, vahvistusharha can reinforce incorrect beliefs, amplify misinformation, and contribute to polarization. It can distort scientific appraisal, risk assessment, and political judgments, especially under time pressure or when stakes are high. It also influences how people evaluate arguments, weigh evidence, and make decisions.

Mitigating strategies include actively seeking disconfirming evidence, preregistering hypotheses, using structured decision protocols, and engaging diverse viewpoints. In research, methods to counteract bias include blind analysis, replication, and explicit consideration of alternative explanations. Being aware of base rates, applying statistical reasoning, and slowing down the reasoning process can further reduce its impact. Related concepts include cognitive dissonance, belief perseverance, and motivated reasoning.