Confirmation bias

Confirmation bias is one of the most documented cognitive biases in social psychology. The tendency to seek, interpret and remember information in a way that confirms pre-existing beliefs is not a moral failing or a sign of extreme irrationality: it is a mechanism the human brain uses automatically to reduce the cognitive load of processing contradictory information. The problem is that this mechanism generates systematic errors in decision-making when the pre-existing beliefs are incorrect.

The bias manifests at multiple levels. At the individual level, the person who believes an investment is good will read news about that company filtering positive signals and discarding negative ones. At the group level, homogeneous teams make worse decisions than heterogeneous ones precisely because the collective bias reinforces shared blind spots. At the social level, the problem is amplified by social network algorithms, which learn user preferences and serve content that confirms their worldview.

The path to reducing its impact involves concrete strategies: actively seeking information that contradicts the working hypothesis, assigning someone the role of "devil's advocate" in important decisions, tracking own predictions and evaluating them retrospectively. None of these strategies eliminates the bias because it is structural to cognitive functioning, but they reduce its impact on decisions that really matter.