Cognitive Biases

The heuristics and biases program, initiated by Amos Tversky and Daniel Kahneman in the early 1970s, revolutionized the understanding of human decision-making. Until then, economic and psychological models assumed that people were rational agents who maximized expected utility. Tversky and Kahneman experimentally demonstrated that humans use mental shortcuts — heuristics — that, while efficient in many cases, produce predictable and systematic errors. Anchoring causes our numerical estimates to be influenced by an arbitrary initial value. The availability heuristic leads us to judge the probability of an event by how easily examples come to mind. The representativeness heuristic makes us evaluate the probability that an item belongs to a category based on its resemblance to the category's prototype, ignoring base rates.

Among the most studied biases, confirmation bias stands out for its ubiquity: the tendency to seek, interpret, and remember information that confirms our existing beliefs while ignoring contradictory evidence. The Dunning-Kruger effect describes how people with low competence in an area tend to overestimate their abilities, while highly competent people tend to underestimate theirs. The sunk cost fallacy leads us to continue investing in a losing project because we have already invested heavily, rather than rationally evaluating future prospects. Hindsight bias makes us believe, once we know the outcome, that it was predictable all along.

It is important to distinguish cognitive biases from cognitive distortions. Cognitive biases are universal information-processing tendencies that affect all people under normal conditions — they are part of standard human cognitive functioning. Cognitive distortions, by contrast, are clinically relevant thought patterns associated with psychopathology, identified by Aaron Beck in the context of depression and anxiety. Although there is conceptual overlap — catastrophic thinking can be understood as both a bias and a distortion — the clinical context differs. The "bias blind spot" is particularly fascinating: it is the tendency to see biases in others but not in oneself, and it is one of the hardest biases to correct.

Debiasing techniques include training in statistics and probability, consideration of alternatives, third-person perspective-taking, and creating systems and procedures that reduce the impact of biases on important decisions. However, research shows that simply knowing about a bias is insufficient to avoid it — deliberate practice and often structural supports are needed. Biases can be classified by category: decision-making biases (anchoring, framing effect, loss aversion), social biases (halo effect, in-group bias, fundamental attribution error), memory biases (misinformation effect, cryptomnesia), and attentional biases.

Gerd Gigerenzer has proposed an alternative perspective with his ecological rationality program. According to Gigerenzer, many of the "biases" identified by Tversky and Kahneman are not errors but adaptive heuristics that work well in the natural environments for which they evolved. Fast-and-frugal heuristics — such as "recognition" or "take-the-best" — can produce decisions as good as or better than complex algorithms when information is incomplete and time is limited. This view does not deny the existence of biases but questions their interpretation as cognitive defects, proposing instead that they are the acceptable price of an agile and efficient cognitive system in uncertain environments.