Adaptive bias is the idea that the human brain has evolved to reason adaptively, rather than truthfully or even rationally, and that cognitive bias may have evolved as a mechanism to reduce the overall cost of cognitive errors as opposed to merely reducing the number of cognitive errors, when faced with making a decision under conditions of uncertainty.

Error Management Theory

According to Error Management Theory, when making decisions under conditions of uncertainty, two kinds of errors need to be taken into account - "false positives", i.e. deciding that a risk or benefit exists when it does not, and "false negatives", i.e. failing to notice a risk or benefit that exists. False positives are also commonly called "Type 1 errors", and false negatives are called "Type 2 errors".

Where the cost or impact of a type 1 error is much greater than the cost of a type 2 error (e.g. the water is safe to drink), it can be worthwhile to bias the decision making system towards making fewer type 1 errors, i.e. making it less likely to conclude that a particular situation exists. This by definition would also increase the number of type 2 errors. Conversely, where a false positive is much less costly than a false negative (blood tests, smoke detectors), it makes sense to bias the system towards maximising the probability that a particular (very costly) situation will be recognised, even if this often leads to the (relatively un-costly) event of noticing something that is not actually there. This situation is exhibited in modern airport screening -- maximizing the probably of preventing a high cost terrorist event results in frequent, low-cost screening hassles for harmless travelers who represent a minimal threat.

Martie G. Haselton and David M. Buss (2003) state that cognitive bias can be expected to have developed in humans for cognitive tasks where:

• Decision making is complicated by a significant signal-detection problem (i.e. when there is uncertainty)
• The solution to the particular kind of decision making problem has had a recurrent effect on survival and fitness throughout evolutionary history.
• The costs of a "false positive" or "false negative" error dramatically outweighs the cost of the alternative type of error

The Costly Information Hypothesis

The costly information hypothesis is used to explore how adaptive biases relate to cultural evolution within the field of dual inheritance theory. The focus is on the evolutionary trade-offs in cost between individual learning, (e.g., operant conditioning) and social learning. If more accurate information that could be acquired through individual learning is too costly, evolution may favor learning mechinisms that, in turn, are biased towards less costly, (though potentially less accurate), information via social learning.

See also

• Guided variation & biased transmission - Adaptive biases in dual inheritance theory
• Psychological adaptation

References

• Haselton, M.G., Nettle, D. & Andrews, P.W. (2005). The evolution of cognitive bias. In D. M. Buss (Ed.), Handbook of evolutionary psychology (pp. 724-746). Hoboken: Wiley. Full text
• Haselton, M.G. & Buss, D.M. (2003). Biases in Social Judgment: Design Flaws or Design Features? In J. Forgas, K. Williams, & B. von Hippel (Eds.), Responding to the social world: Implicit and explicit processes in social judgments and decisions. New York, NY: Cambridge. Full text
• Henrich, J. & McElreath, R. (2007). Dual Inheritance Theory: The evolution of human cultural capacities and cultural evolution. In R. Dunbar and L. Barrett, (Eds.), Oxford Handbook of Evolutionary Psychology, Ch. 38. Oxford: Oxford Univ Press. Full text