Availability heuristic
Encyclopedia
The availability heuristic is a phenomenon
(which can result in a cognitive bias
) in which people predict the frequency of an event, or a proportion within a population, based on how easily an example can be brought to mind.
This phenomenon was first reported by psychologist
s Amos Tversky
and Daniel Kahneman
, who also identified the representativeness heuristic
. To see how availability differs from related terms vividness and salience
, see availability, salience and vividness
.
operates on the notion that "if you can think of it, it must be important." Media coverage can help fuel a person's example bias with widespread and extensive coverage of unusual events, such as homicide or airline accidents, and less coverage of more routine, less sensational events, such as common diseases or car accidents. For example, when asked to rate the probability of a variety of causes of death, people tend to rate more "newsworthy" events as more likely because they can more readily recall an example from memory. For example, in the USA, people rate the chance of death by homicide higher than the chance of death by stomach cancer, even though death by stomach cancer is five times higher than death by homicide. Moreover, unusual and vivid events like homicides, shark attacks, or lightning are more often reported in mass media than common and unsensational causes of death like common diseases. Another instance of biased ratings is the relative overestimation of plane crash deaths, compared to car-accident deaths.
In one experiment that occurred before the 1976 US Presidential election, participants were asked simply to imagine Gerald Ford
winning the upcoming election. Those who were asked to do this subsequently viewed Ford as being significantly more likely to win the upcoming election. A similar result was obtained from participants that had been asked to imagine Jimmy Carter
winning. Analogous results were found with vivid versus pallid descriptions of outcomes in other experiments.
These very stories are an example of Availability Heuristic as they might lean the reader into regarding them as likely, even before going through the citations to confirm their truthfulness.
Phenomenon
A phenomenon , plural phenomena, is any observable occurrence. Phenomena are often, but not always, understood as 'appearances' or 'experiences'...
(which can result in a cognitive bias
Cognitive bias
A cognitive bias is a pattern of deviation in judgment that occurs in particular situations. Implicit in the concept of a "pattern of deviation" is a standard of comparison; this may be the judgment of people outside those particular situations, or may be a set of independently verifiable...
) in which people predict the frequency of an event, or a proportion within a population, based on how easily an example can be brought to mind.
This phenomenon was first reported by psychologist
Psychologist
Psychologist is a professional or academic title used by individuals who are either:* Clinical professionals who work with patients in a variety of therapeutic contexts .* Scientists conducting psychological research or teaching psychology in a college...
s Amos Tversky
Amos Tversky
Amos Nathan Tversky, was a cognitive and mathematical psychologist, a pioneer of cognitive science, a longtime collaborator of Daniel Kahneman, and a key figure in the discovery of systematic human cognitive bias and handling of risk. Much of his early work concerned the foundations of measurement...
and Daniel Kahneman
Daniel Kahneman
Daniel Kahneman is an Israeli-American psychologist and Nobel laureate. He is notable for his work on the psychology of judgment and decision-making, behavioral economics and hedonic psychology....
, who also identified the representativeness heuristic
Representativeness heuristic
The representativeness heuristic is a psychological term describing a phenomenon wherein people judge the probability or frequency of a hypothesis by considering how much the hypothesis resembles available data as opposed to using a Bayesian calculation. While often very useful in everyday life, it...
. To see how availability differs from related terms vividness and salience
Salience
Salience or saliency may refer to:* Salience , the state or quality of an item that stands out relative to neighboring items* Salience , relative importance or prominence of a piece of a sign...
, see availability, salience and vividness
Availability, salience and vividness
Availability, salience and vividness are three terms which refer to very similar things in social psychology but have slightly different meanings. They may actually all refer to the same underlying concept, and they positively influence one another, but they are each used consistently in different...
.
Overview
Essentially the availability heuristicHeuristic
Heuristic refers to experience-based techniques for problem solving, learning, and discovery. Heuristic methods are used to speed up the process of finding a satisfactory solution, where an exhaustive search is impractical...
operates on the notion that "if you can think of it, it must be important." Media coverage can help fuel a person's example bias with widespread and extensive coverage of unusual events, such as homicide or airline accidents, and less coverage of more routine, less sensational events, such as common diseases or car accidents. For example, when asked to rate the probability of a variety of causes of death, people tend to rate more "newsworthy" events as more likely because they can more readily recall an example from memory. For example, in the USA, people rate the chance of death by homicide higher than the chance of death by stomach cancer, even though death by stomach cancer is five times higher than death by homicide. Moreover, unusual and vivid events like homicides, shark attacks, or lightning are more often reported in mass media than common and unsensational causes of death like common diseases. Another instance of biased ratings is the relative overestimation of plane crash deaths, compared to car-accident deaths.
Examples
- A person argues that cigarette smoking is not unhealthy because his grandfather smoked three packs of cigarettes a day and lived to be 100. The grandfather's health could simply be an unusual case that does not speak to the health of smokers in general.
- A politician says that walnut farmers need a special farm subsidy. He points to a farmer standing nearby and explains how that farmer will benefit. Others who watch and discuss later agree that the subsidy is needed based on the benefit to that farmer. The farmer, however, might be the only person who will benefit from the subsidy. Walnut farmers in general may not necessarily need this subsidy.
- A person claims to a group of friends that drivers of red cars get more speeding tickets. The group agrees with the statement because a member of the group, "Jim," drives a red car and frequently gets speeding tickets. The reality could be that Jim just drives fast and would get a speeding ticket regardless of the color of car that he drove. Even if statistics show fewer speeding tickets were given to red cars than to other colors of cars, Jim is an available example which makes the statement seem more plausible.
- Someone is asked to estimate the proportion of words that begin with the letter "R" or "K" versus those words that have the letter "R" or "K" in the third position. Most English-speaking people could immediately think of many words that begin with the letters "R" (roar, rusty, ribald) or "K" (kangaroo, kitchen, kale), but it would take a more concentrated effort to think of any words where "R" or "K" is the third letter (street, care, borrow, acknowledge); the immediate answer would probably be that words that begin with "R" or "K" are more common. The reality is that words that have the letter "R" or "K" in the third position are more common. In fact, there are three times as many words that have the letter "K" in the third position, as have it in the first position.
- Where an anecdote ("I know a Brazilian man who...") is used to "prove" an entire proposition or to support a bias, the availability heuristic is in play. In these instances the ease of imagining an example or the vividness and emotional impact of that example becomes more credible than actual statistical probability. Because an example is easily brought to mind or mentally "available," the single example is considered as representative of the whole rather than as just a single example in a range of data.
- A person sees several news stories of cats leaping out of tall trees and surviving, so he believes that cats must be robust to long falls. However, these kinds of news reports are far more common than reports where a cat falls out of the tree and dies, which may in fact be a more common event.
Imagining outcomes
One important corollary finding to this heuristic is that people asked to imagine an outcome tend to immediately view it as more likely than people that were not asked to imagine the specific outcome. If group A were asked to imagine a specific outcome and then asked if it were a likely outcome, and group B were asked whether the same specific outcome were likely without being asked to imagine it first, the members of group A tend to view the outcome as more likely than the members of group B, thereby demonstrating the tendency toward using an availability heuristic as a basis for logic.{Caroll, 1978}In one experiment that occurred before the 1976 US Presidential election, participants were asked simply to imagine Gerald Ford
Gerald Ford
Gerald Rudolph "Jerry" Ford, Jr. was the 38th President of the United States, serving from 1974 to 1977, and the 40th Vice President of the United States serving from 1973 to 1974...
winning the upcoming election. Those who were asked to do this subsequently viewed Ford as being significantly more likely to win the upcoming election. A similar result was obtained from participants that had been asked to imagine Jimmy Carter
Jimmy Carter
James Earl "Jimmy" Carter, Jr. is an American politician who served as the 39th President of the United States and was the recipient of the 2002 Nobel Peace Prize, the only U.S. President to have received the Prize after leaving office...
winning. Analogous results were found with vivid versus pallid descriptions of outcomes in other experiments.
These very stories are an example of Availability Heuristic as they might lean the reader into regarding them as likely, even before going through the citations to confirm their truthfulness.
See also
- Affect heuristicAffect heuristicThe affect heuristic is a heuristic in which current affect influences decisions. Simply put, it is a "rule of thumb" instead of a deliberative decision...
- Anecdotal evidenceAnecdotal evidenceThe expression anecdotal evidence refers to evidence from anecdotes. Because of the small sample, there is a larger chance that it may be true but unreliable due to cherry-picked or otherwise unrepresentative of typical cases....
- Anecdotal valueAnecdotal valueIn economics, anecdotal value refers to the primarily social and political value of an anecdote or anecdotal evidence in promoting understanding of a social, cultural, or economic phenomenon...
- Attribute substitutionAttribute substitutionAttribute substitution is a psychological process thought to underlie a number of cognitive biases and perceptual illusions. It occurs when an individual has to make a judgment that is computationally complex, and instead substitutes a more easily calculated heuristic attribute...
- Gambler's fallacyGambler's fallacyThe Gambler's fallacy, also known as the Monte Carlo fallacy , and also referred to as the fallacy of the maturity of chances, is the belief that if deviations from expected behaviour are observed in repeated independent trials of some random process, future deviations in the opposite direction are...
- Misleading vividnessMisleading vividnessMisleading vividness is a term that can be applied to anecdotal evidence describing an occurrence, even if it is an exceptional occurrence, with sufficient detail to permit hasty generalizations about the occurrence...
- Processing fluencyProcessing fluencyProcessing fluency is the ease with which information is processed in the mind. The ease with which perceptual stimuli are processed is perceptual fluency; the ease with which information can be retrieved from memory is retrieval fluency....
- Representativeness heuristicRepresentativeness heuristicThe representativeness heuristic is a psychological term describing a phenomenon wherein people judge the probability or frequency of a hypothesis by considering how much the hypothesis resembles available data as opposed to using a Bayesian calculation. While often very useful in everyday life, it...
- Texas sharpshooter fallacyTexas sharpshooter fallacyThe Texas sharpshooter fallacy is a logical fallacy in which pieces of information that have no relationship to one another are called out for their similarities, and that similarity is used for claiming the existence of a pattern. This fallacy is the philosophical/rhetorical application of the...
- Agenda-setting theoryAgenda-setting theoryAgenda-Setting Theory states that the news media have a large influence on audiences, in terms of what stories to consider newsworthy and how much prominence and space to give them. Agenda-setting theory’s main postulate is salience transfer. Salience transfer is the ability of the news media to...
- List of cognitive biases
External links
- http://www.posbase.uib.no/posbase/Presentasjoner/P_Tversky%20&%20Kahneman%20(1973).ppt - A Powerpoint presentation on the classical experiments about the availability heuristic by Tversky and Kahneman.
- http://posbase.uib.no/posbase/Presentasjoner/P_Lichtenstein%20et%20al.%20(1978).ppt - A Powerpoint presentation on the frequency estimate study by Lichtenstein and colleagues.
- Test Yourself: Decision Making and the Availability Heuristic