News media highlight memorable occurrences that give an event the inaccurate appearance of frequency.
Availability bias is a human cognitive bias that causes people to overestimate the probability of events associated with memorable or vivid occurrences. As memorable events are magnified further by media coverage, prejudice is compounded at the societal level. Two prominent examples would be estimates of the probability of plane crashes and the frequency with which children are abducted. Both of these events are quite rare, but the vast majority of the population believes they are more common than they actually are and behaves accordingly.
Child theft is a rare occurrence, but availability bias suggests a high probability of abduction.
In fact, people are much more likely to die in a car crash than in a plane crash, and children are more likely to die in an accident than to be abducted. Most people think the reverse is true, however, because less likely events are more “available” – more memorable. Looking at the literature or even just the interactions of daily life will reveal thousands of examples of availability bias in action.
Belief in the probability of a plane crash is caused by availability bias.
Availability bias is at the root of many other human biases and culture-level effects. For example, medieval medicine was probably hardly more effective than leaving a disease alone to heal itself, but because the times when therapy “worked” are more readily available in the minds of many, practicing medicine was generally considered effective, whether or not it worked. not. really was.
The study of this bias was initiated by psychologists Amos Tversky and Daniel Kahneman, who founded the field of “heuristics and biases” and developed a model called prospect theory to explain systematic bias in human decision making. Kahneman later won the Nobel Prize in economics in 2002 for his work, despite never having taken an economics course. Tversky, his longtime partner in researching heuristics and biases, died in 1996.
A concept closely linked to availability bias is base rate neglect. Base rate neglect refers to integrating irrelevant information into a probability judgment, biasing it from the natural base rate. An example would be letting someone into college on the basis of an interview alone, when empirical studies have shown that past performance and grades are the best possible indicator of future performance and that interviews only get in the way of assessment. As people like to “see things for themselves”, however, interviews are likely to continue to take place even in the absence of any support for their effectiveness.