Cognitive Heuristics

To explain our tendency to systematically make bad judgements in some circumstances, Kahneman and Tvesky proposed that we often rely on cognitive short-cuts or heuristics. For example, to evaluate the probability or frequency of an event (e.g. how likely am I to be attacked by a shark whilst swimming off the coast of South Africa), we estimate the ease with which we can recall similar events.

This availability heuristic has the advantage of placing only limited demands on our cognitive resources – assessing how easy it would be to recall something from memory is quick and easy. However, it also means that we are prone to overestimate the probability and frequency of events which are particularly memorable - such as shark attacks.

Other psychologists have drawn attention to different ways in which irrationality is commonly manifested. How do you rate your driving ability? Much worse than average, a little worse than average, about average, a little better than average, or a lot better than average? In fact, the number of people who consider themselves better than average drivers outnumber those who consider themselves worse than average.

Clearly at least some of these people are being unrealistically optimistic about their ability.

This unrealistic optimism effect is partnered by two similar ones: the self-serving bias (e.g. most people think they are better looking than the average person) and the illusion of control (we tend to think that we have more control of events than is actually the case).

Indeed some research suggests that those with the most accurate level of optimism, the most accurate views of their own attractiveness, and the most accurate sense of the degree to which they are in control, are the acutely depressed.

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