A cognitive bias is a systematic pattern of deviation from norm or rationality in judgment. Individuals create their own "subjective reality" from their perception of the input. An individual's construction of reality, not the objective input, may dictate their behavior in the world. Thus, cognitive biases may sometimes lead to perceptual distortion, inaccurate judgment, illogical interpretation, and irrationality.
While cognitive biases may initially appear to be negative, some are adaptive. They may lead to more effective actions in a given context. Furthermore, allowing cognitive biases enables faster decisions which can be desirable when timeliness is more valuable than accuracy, as illustrated in heuristics. Other cognitive biases are a "by-product" of human processing limitations, resulting from a lack of appropriate mental mechanisms (bounded rationality), the impact of an individual's constitution and biological state (see embodied cognition), or simply from a limited capacity for information processing.
A continually evolving list of cognitive biases has been identified over the last six decades of research on human judgment and decision-making in cognitive science, social psychology, and behavioral economics. The study of cognitive biases has practical implications for areas including clinical judgment, entrepreneurship, finance, and management.
Overview
The notion of cognitive biases was introduced by Amos Tversky and Daniel Kahneman in 1972 and grew out of their experience of people's innumeracy, or inability to reason intuitively with the greater orders of magnitude. Tversky, Kahneman, and colleagues demonstrated several replicable ways in which human judgments and decisions differ from rational choice theory. Tversky and Kahneman explained human differences in judgment and decision-making in terms of heuristics. Heuristics involve mental shortcuts which provide swift estimates about the possibility of uncertain occurrences. Heuristics are simple for the brain to compute but sometimes introduce "severe and systematic errors." For example, the representativeness heuristic is defined as "The tendency to judge the frequency or likelihood" of an occurrence by the extent of which the event "resembles the typical case."
The "Linda Problem" illustrates the representativeness heuristic (Tversky & Kahneman, 1983). Participants were given a description of "Linda" that suggests Linda might well be a feminist (e.g., she is said to be concerned about discrimination and social justice issues). They were then asked whether they thought Linda was more likely to be (a) a "bank teller" or (b) a "bank teller and active in the feminist movement." A majority chose answer (b). This error (mathematically, answer (b) cannot be more likely than answer (a)) is an example of the "conjunction fallacy"; Tversky and Kahneman argued that respondents chose (b) because it seemed more "representative" or typical of persons who might fit the description of Linda. The representativeness heuristic may lead to errors such as activating stereotypes and inaccurate judgments of others (Haselton et al., 2005, p. 726).
Critics of Kahneman and Tversky, such as Gerd Gigerenzer, alternatively argued that heuristics should not lead us to conceive of human thinking as riddled with irrational cognitive biases. They should rather conceive rationality as an adaptive tool, not identical to the rules of formal logic or the probability calculus. Nevertheless, experiments such as the "Linda problem" grew into heuristics and biases research programs, which spread beyond academic psychology into other disciplines including medicine and political science.
Definitions
Types
Biases can be distinguished on a number of dimensions. Examples of cognitive biases include - Biases specific to groups (such as the risky shift) versus biases at the individual level. Biases that affect decision-making, where the desirability of options has to be considered (e.g., sunk costs fallacy). Biases, such as illusory correlation, that affect judgment of how likely something is or whether one thing is the cause of another. Biases that affect memory, such as consistency bias (remembering one's past attitudes and behavior as more similar to one's present attitudes). Biases that reflect a subject's motivation, for example, the desire for a positive self-image leading to egocentric bias and the avoidance of unpleasant cognitive dissonance.
Other biases are due to the particular way the brain perceives, forms memories and makes judgments. This distinction is sometimes described as "hot cognition" versus "cold cognition", as motivated reasoning can involve a state of arousal. Among the "cold" biases,