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{{Short description|Bias towards recently acquired information}}
The '''availability heuristic''' is a mental shortcut that occurs when people make judgments about the probability of events by how easy it is to think of examples. The availability heuristic operates on the notion that, "if you can think of it, it must be important." The availability of consequences associated with an action is positively related to perceptions of the magnitude of the consequences of that action. In other words, the easier it is to recall the consequences of something, the greater we perceive these consequences to be. Sometimes, this heuristic is beneficial, but the frequencies that events come to mind are usually not accurate reflections of their actual probability in real life.<ref name="tversky">{{cite journal|last=Tversky|first=A|coauthors=Kahneman|title=Availability: A heuristic for judging frequency and probability|journal=Cognitive Psychology|year=1973|volume=5|issue=1|pages=207–233|doi=10.1016/0010-0285(73)90033-9}}</ref> For example, if someone asked you whether your college had more students from Colorado or more from California, under the availability heuristic, you would probably answer the question based on the relative availability of examples of Colorado students and California students. If you recall more students that come from California that you know, you will be more likely to conclude that more students in your college are from California than from Colorado.<ref>{{cite book|last=Matlin|first=Margaret|title=Cognition|year=2009|publisher=John Wiley & Sons, Inc|location=Hoboken, NJ|isbn=978-0-470-08764-0|page=413}}</ref>


The '''availability heuristic''', also known as '''availability bias''', is a mental shortcut that relies on immediate examples that come to a given person's mind when evaluating a specific topic, concept, method, or decision. This ], operating on the notion that, if something can be ]ed, it must be important, or at least more important than alternative solutions not as readily recalled,<ref name="EsgateGroome2005">{{Cite book |last1=Esgate |first1=Anthony |url=https://books.google.com/books?id=B4agXAUYv6QC |title=An Introduction to Applied Cognitive Psychology |last2=Groome |first2=David |publisher=Psychology Press |year=2005 |isbn=978-1-84169-318-7 |page=201}}</ref> is inherently biased toward recently acquired information.<ref>{{Cite web |title=Availability Heuristic |url=https://www.oxfordreference.com/view/10.1093/oi/authority.20110803095436724 |website=Oxford Reference }}</ref><ref>{{Cite web |last=Phung |first=Albert |date=February 25, 2009 |title=Behavioral Finance: Key Concept- Overreaction and Availability Bias |url=http://www.investopedia.com/university/behavioral_finance/ |access-date=December 1, 2013 |website=Investopedia |page=10}}</ref>
==Overview and History==
When faced with the difficult task of judging probability or frequency, people use a limited number of strategies, called ]s, to simplify these judgements. One of these strategies, the availability heuristic, is the tendency to make a judgement about the frequency of an event based on how easy it is to recall similar instances.<ref name="tversky" /> In 1973, ] and ] first studied this phenomenon and labeled it the Availability Heuristic. The availability heuristic is an unconscious process that operates on the notion that, "if you can think of it, it must be important." <ref name="tversky" /> In other words, how easily an example can be called to mind is related to perceptions about how often this event occurs. Thus, people tend to use a readily accessible attribute to base their beliefs about a relatively distant concept.<ref>{{cite journal|last=Kahneman|first=D|coauthors=Tversky, A|title=The psychology of preferences|journal=Scientific American|year=1982|month=January|volume=246|pages=160–173}}</ref>


The mental availability of an action's consequences is positively related to those consequences' perceived magnitude. In other words, the easier it is to recall the consequences of something, the greater those consequences are often perceived to be. Most notably, people often rely on the content of their recall if its implications are not called into question by the difficulty they have in recalling it.<ref name="schwarz">{{Cite journal |last1=Schwarz |first1=Norbert |last2=Bless |first2=Herbert |last3=Strack |first3=Fritz |last4=Klumpp |first4=Gisela |last5=Rittenauer-Schatka |first5=Helga |last6=Simons |first6=Annette |year=1991 |title=Ease of retrieval as information: Another look at the availability heuristic |url=http://www.ssoar.info/ssoar/handle/document/6723 |journal=Journal of Personality and Social Psychology |volume=61 |issue=2 |pages=195–202 |doi=10.1037/0022-3514.61.2.195}}</ref>
In an experiment to test this heuristic, Tversky and Kahneman presented participants with four lists of names: two lists with the names of 19 famous women and 20 less famous men, and two lists with the names of 19 famous men and 20 less famous women. The first group was asked to recall as many names as possible and the second group was asked to estimate which class of names was more frequent: famous or less famous. The famous names were most easily recalled compared to the less famous names, and despite the fact that the less famous names were more frequent, the majority of the participants incorrectly judged that the famous names occurred more often. While the availability heuristic is an effective strategy in many situations, when judging probability the availability heuristic can lead to systematic errors.<ref name="tversky" />


==Overview and history==
==Research==
].]]
In the late 1960s and early 1970s, ] and ] began work on a series of papers examining "heuristic and ]es" used in judgment under ]. Prior to that, the predominant view in the field of human ] was that humans are ]s. Kahneman and Tversky explained that judgment under uncertainty often relies on a limited number of simplifying heuristics rather than extensive ]ic processing. Soon, this idea spread beyond academic psychology, into law, medicine, and political science. This research questioned the descriptive adequacy of idealized models of judgment, and offered insights into the ]es that explained human error without invoking motivated ].<ref name="books.google.com">{{Cite book |last1=Gilovich |first1=Thomas |url=https://books.google.com/books?id=FfTVDY-zrCoC&q=history+overview+OR+OR+OR+definition+%22availability+heuristics%22&pg=PR11 |title=Heuristics and Biases: The Psychology of Intuitive Judgment |last2=Griffin |first2=Dale |last3=Kahneman |first3=Daniel |date=2002-07-08 |publisher=Cambridge University Press |isbn=9780521796798}}</ref> One simplifying strategy people may rely on is the tendency to make a judgment about the frequency of an event based on how many similar instances are brought to mind. In 1973, Amos Tversky and Daniel Kahneman first studied this phenomenon and labeled it the "availability heuristic". An availability heuristic is a mental shortcut that relies on immediate examples that come to a given person's mind when evaluating a specific topic, concept, method, or decision. As follows, people tend to use a readily available fact to base their beliefs on a comparably distant concept. There has been much research done with this heuristic, but studies on the issue are still questionable with regard to the underlying process. Studies illustrate that manipulations intended to increase the subjective experience of ease of recall are also likely to affect the amount of recall. Furthermore, this makes it difficult to determine whether the obtained estimates of frequency, likelihood, or typicality are based on participants' phenomenal experiences or on a biased sample of recalled information.<ref name="books.google.com" />


However, some textbooks have chosen the latter interpretation introducing the availability heuristic as "one's judgments are always based on what comes to mind".{{citation needed|date=August 2024}} For example, if a person is asked whether there are more words in the English language that start with a k or have k as the third letter, the person will probably be able to think of more words that begin with the letter k, concluding incorrectly that k is more ] as the first letter than the third.<ref>{{Cite news |last1=Gilovich, T. D. |last2=Griffin, D. |last3=Kahneman, D. |date=2002 |title=Heuristics and Biases: The Psychology of Intuitive Judgment |publisher=New York, NY: Cambridge University Press.}}</ref> In this Misplaced Pages article itself, for example, there are multiple instances of words such as "likely", "make", "take", "ask" and indeed "Misplaced Pages", but (aside from names) only a couple of initial K's: "know" and "key".
In a study by Schwarz et al., participants were asked to describe either 6 or 12 examples of assertive or unassertive behavior. Participants were later asked to rate their own assertiveness. The results indicated that participants rated themselves as more assertive after describing 6, rather than 12, examples for the assertive behavior condition, and conversely rated themselves as less assertive after describing 6, rather than 12, examples for the unassertive behavior condition. The study reflected that the recalled content was qualified by the ease with which the content could be brought to mind (it was easier to recall 6 examples than 12).<ref name="schwarz">{{cite journal|last=Schwarz|first=N|coauthors=Strack, F., Bless, H., Klumpp, G., Rittenauer-Schatka, H., & Simons, A.|title=Ease of retrieval as information: Another look at the availability heuristic|journal=Journal of Personality and Social Psychology|year=1991|volume=61|issue=2|pages=195–202}}</ref>


==Research==
In another study, subjects were asked, "If a random word is taken from an English text, is it more likely that the word starts with a K, or that K is the third letter?" Most English-speaking people could immediately think of many words that begin with the letter "K" (kangaroo, kitchen, kale), but it would take a more concentrated effort to think of any words where "K" is the third letter (acknowledge, ask). Results indicated that participants overestimated the number of words that began with the letter "K", but underestimated the number of words that had "K" as the third letter. Researchers concluded that people answer questions like these by comparing the availability of the two categories and assessing how easily they can recall these instances. In other words, it is easier to think of words that begin with "K", than words with "K" as the third letter. Thus, people judge words beginning with a "K" to be a more common occurrence. In reality, however, a typical text contains twice as many words that have "K" as the third letter than "K" as the first letter. There are three times as more words with "K" in the third position than words that begin with "K".<ref name="tversky" />
Chapman (1967) described a bias in the judgment of the frequency with which two events co-occur. This demonstration showed that the ] of paired stimuli resulted in participants overestimating the frequency of the pairings.<ref>{{Cite journal |last=Chapman |first=L.J |year=1967 |title=Illusory correlation in observational report |journal=Journal of Verbal Learning |volume=6 |pages=151–155 |doi=10.1016/s0022-5371(67)80066-5}}</ref> To test this idea, participants were given information about several hypothetical mental patients. The data for each patient consisted of a clinical diagnosis and a drawing made by the patient. Later, participants estimated the frequency with which each diagnosis had been accompanied by various features of the drawing. The subjects vastly overestimated the frequency of this co-occurrence (such as suspiciousness and peculiar eyes). This effect was labeled the ]. Tversky and Kahneman suggested that availability provides a natural account for the illusory-correlation effect. The strength of the association between two events could provide the basis for the judgment of how frequently the two events co-occur. When the association is strong, it becomes more likely to conclude that the events have been paired frequently. Strong associations will be thought of as having occurred together frequently.<ref name="tversky">{{Cite journal |last1=Tversky |first1=Amos |last2=Kahneman |first2=Daniel |year=1973 |title=Availability: A heuristic for judging frequency and probability |journal=Cognitive Psychology |volume=5 |issue=2 |pages=207–232 |doi=10.1016/0010-0285(73)90033-9 |issn=0010-0285}}</ref>


In Tversky & Kahneman's first examination of availability heuristics, subjects were asked, "If a random word is taken from an English text, is it more likely that the word starts with a K, or that K is the third letter?" They argue that English-speaking people would immediately think of many words that begin with the letter "K" (kangaroo, kitchen, kale), but that it would take a more concentrated effort to think of any words in which "K" is the third letter (acknowledge, ask). Results indicated that participants overestimated the number of words that began with the letter "K" and underestimated the number of words that had "K" as the third letter. Tversky and Kahneman concluded that people answer questions like these by comparing the availability of the two categories and assessing how easily they can recall these instances. In other words, it is easier to think of words that begin with "K", more than words with "K" as the third letter. Thus, people judge words beginning with a "K" to be a more common occurrence. In reality, however, a typical text contains twice as many words that have "K" as the third letter than "K" as the first letter.<ref name="tversky" />
Chapman (1967) described a bias in the judgment of the frequency with which two events co-occur. This demonstration showed that the co-occurrence of paired stimuli resulted in participants overestimating the frequency of the pairings.<ref>{{cite journal|last=Chapman|first=L.J|title=Illusory correlation in observational report|journal=Journal of Verbal Learning|year=1967|volume=6|pages=151–155}}</ref> To test this idea, participants were given information about several hypothetical mental patients. The data for each patient consisted of a clinical diagnosis and a drawing made by the patient. Later, participants estimated the frequency with which each diagnosis had been accompanied by various features of the drawing. The subjects vastly overestimated the frequency of this co-occurrence (such as suspiciousness and peculiar eyes). This effect was labeled the ]. Tversky and Kahneman suggested that availability provides a natural account for the illusory-correlation effect. The strength of the association between two events could provide the basis for the judgment of how frequently the two events co-occur. When the association is strong, it becomes more likely to conclude that the events have been paired frequently. Strong associations will be thought of as having occurred together frequently.<ref name="tversky" />


In Tversky and Kahneman's seminal paper, they include findings from several other studies, which also show support for the availability heuristic. Apart from their findings in the "K" study, they also found:
Research in 1992 used mood manipulation to influence the availability heuristic by placing participants into a sad mood condition or a happy mood condition. People in the sad mood condition recalled better than those in the happy mood condition, revealing that the power of the availability heuristic changes in certain conditions.<ref>{{cite journal|last=Colin|first=M|coauthors=Campbell, L.|title=Memory accessibility and probability of judgements:An experimental evaluation of the availability heuristic|journal=Journal of Personality and Social Psychology|year=1992|volume=63|issue=6|pages=890–902}}</ref>
:When participants were shown two visual structures and asked to pick the structure that had more paths, participants saw more paths in the structure that had more obvious available paths. In the structure that participants chose, there were more columns and shorter obvious paths, making it more available to them. When participants were asked to complete tasks involving estimation, they would often underestimate the end result. Participants were basing their final estimation on a quick first impression of the problem. Participants particularly struggled when the problems consisted of multiple steps. This occurred because participants were basing their estimation on an initial impression. Participants failed to account for the high rate of growth in the later steps due to the impression they formed in the initial steps. This was shown again in a task that asked participants to estimate the answer to a multiplication task, in which the numbers were presented as either 1x2x3x4x5x6x7x8 or 8x7x6x5x4x3x2x1. Participants who were presented the equation with the larger numbers first (8x7x6...), estimated a significantly higher result than participants with the lower numbers first (1x2x3...). Participants were given a short amount of time to make the estimation, thus participants based their estimates off of what was easily available, which in this case was the first few numbers in the sequence.<ref name="tversky" />


==Examples== == Explanations ==
Many researchers have attempted to identify the psychological process which creates the availability heuristic.


Tversky and Kahneman argue that the number of examples recalled from memory is used to infer the frequency with which such instances occur. In an experiment to test this explanation, participants listened to lists of names containing either 19 famous women and 20 less famous men or 19 famous men and 20 less famous women. Subsequently, some participants were asked to recall as many names as possible whereas others were asked to estimate whether male or female names were more frequent on the list. The names of the famous celebrities were recalled more frequently compared to those of the less famous celebrities. The majority of the participants incorrectly judged that the gender associated with more famous names had been presented more often than the gender associated with less famous names. Tversky and Kahneman argue that although the availability heuristic is an effective strategy in many situations when judging probability, use of this heuristic can lead to predictable patterns of errors.<ref name="tversky" />
*A person claims to a group of friends that those who drive red cars receive more speeding tickets. The group agrees with the statement because a member of the group drives a red car and frequently receives speeding tickets. The reality could be that he just drives fast and would receive 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, he is an available example which makes the statement seem more plausible.<ref>{{cite journal|last=Manis|first=Melvin|coauthors=Shelder, J., Jonides, J., Nelson, N.E.|title=Availability Heuristic in Judgments of Set Size and Frequency of Occurrence|journal=Journal of Personality and Social Psychology|year=1993|volume=65|issue=3|pages=448–457}}</ref>


Schwarz and his colleagues, on the other hand, proposed the ''ease of retrieval'' explanation, wherein the ease with which examples come to mind, not the number of examples, is used to infer the frequency of a given class. In a study by Schwarz and colleagues to test their explanation, participants were asked to recall either six or twelve examples of their assertive or very unassertive behavior. Participants were later asked to rate their own assertiveness. Pretesting had indicated that although most participants were capable of generating twelve examples, this was a difficult task. The results indicated that participants rated themselves as more assertive after describing six examples of assertive compared with unassertive behavior, but rated themselves as less assertive after describing twelve examples of assertive compared with unassertive behavior. The study reflected that the extent to which recalled content impacted judgment was determined by the ease with which the content could be brought to mind (it was easier to recall 6 examples than 12), rather than the amount of content brought to mind.<ref name="schwarz" />
*Where an anecdote ("I know a Brazilian man who&nbsp;...") 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 representative of the whole rather than as just an ] example in a range of data.<ref name="tversky" /> An example is when a person argues that cigarette smoking is not unhealthy because his grandfather smoked three packs of cigarettes each day and lived to be 100 years old. (The grandfather's health could be an exception to the rule.)<ref>{{cite book|last=Esgate, Groome|first=A, D|title=An Introduction to Applied Cognitive Psychology|year=2004|publisher=Psychology Press|isbn= 1-84169-317-0}}</ref>


Research by Vaughn (1999) looked at the effects of ] on the use of the availability heuristic. College students were asked to list either three or eight different study methods they could use in order to get an A on their final exams. The researchers also manipulated the time during the semester they would ask the students to complete the questionnaire. Approximately half of the participants were asked for their study methods during the third week of classes, and the other half were asked on the last day of classes. Next, participants were asked to rate how likely they would be to get an A in their easiest and hardest classes. Participants were then asked to rank the difficulty they experienced in recalling the examples they had previously listed. The researchers hypothesized that students would use the availability heuristic, based on the number of study methods they listed, to predict their grade only when asked at the beginning of the semester and about their hardest final. Students were not expected to use the availability heuristic to predict their grades at the end of the semester or about their easiest final. The researchers predicted this use of the availability heuristic because participants would be uncertain about their performance throughout the semester. The results indicated that students used the availability heuristic, based on the ease of recall of the study methods they listed, to predict their performance when asked at the beginning of the semester and about their hardest final. If the student listed only three study methods, they predicted a higher grade at the end of the semester only on their hardest final. If students listed eight study methods, they had a harder time recalling the methods and thus predicted a lower final grade on their hardest final. The results were not seen in the easy final condition because the students were certain they would get an A, regardless of the study method. The results supported this hypothesis and gave evidence to the fact that levels of uncertainty affect the use of the availability heuristic.<ref>{{Cite journal |last=Vaughn |first=Leigh Ann |year=1999 |title=Effects of uncertainty on use of the availability of heuristic for self-efficacy judgments |url=https://deepblue.lib.umich.edu/bitstream/2027.42/34564/1/943_ftp.pdf |journal=European Journal of Social Psychology |volume=29 |issue=2/3 |pages=407–410 |doi=10.1002/(sici)1099-0992(199903/05)29:2/3<407::aid-ejsp943>3.0.co;2-3 |hdl-access=free |hdl=2027.42/34564}}</ref>
*A person sees several news stories about 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 could be more common.<ref name="tversky" />

*A recent newspaper subscriber might compare the number of newspapers delivered versus those that were not delivered in order to calculate newspaper delivery failure. In this case, the calculation of delivery failure depends on the number of incidents recalled. However, it will be hard to recall all specific instances if the subscriber is trying to recall all newspaper deliveries over an extensive period of time.<ref>{{cite journal|last=Folkes|first=Valerie S.|title=The Availability Heuristic and Perceived Risk|journal=Journal of Consumer Research|year=1988|month=June|volume=15|issue=1}}</ref>

*After seeing many news stories of home foreclosures, people may judge that the likelihood of this event is greater. This may be true because it is easier to think of examples of this event.<ref name="tversky" />


==Applications== ==Applications==


===Media=== ===Media===
After seeing news stories about child abductions, people may judge that the likelihood of this event is greater. 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 "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.<ref>{{cite journal|last=Briñol|first=P|coauthors=Petty, R.E, & Tormala, Z.L.|title=The malleable meaning of subjective ease|journal=Psychological Science|year=2006|volume=17|pages=200–206|doi=10.1111/j.1467-9280.2006.01686.x}}</ref> After seeing news stories about child abductions, people may judge that the ] of this event is greater. ] can help fuel a person's example bias with widespread and extensive coverage of unusual events, such as ] or ]s, and less coverage of more routine, less sensational events, such as common diseases or ]s. For example, when asked to rate the probability of a variety of causes of death, people tend to rate "newsworthy" events as more likely because they can more readily recall an example from memory.<ref>{{Cite web |title=Media's Impact on Society Media & Society Issues Explained |date=27 February 2022 |url=https://mediaandsociety.org/medias-impact-on-society/ |access-date=2022-11-14 |language=en-US}}</ref> Moreover, unusual and vivid events like homicides, ], or ] are more often reported in mass media than common and un-sensational causes of death like common diseases.<ref>{{Cite web |date=2019-08-04 |title=Social Media's Impact on Society |url=https://www.adcouncil.org/all-articles/social-medias-impact-on-society |access-date=2022-11-14 |website=Ad Council Org |language=en}}</ref>


For example, many people think that the likelihood of dying from shark attacks is greater than that of dying from being hit by falling airplane parts, when more people actually die from falling airplane parts. When a shark attack occurs, the deaths are widely reported in the media whereas deaths as a result of being hit by falling airplane parts are rarely reported in the media.<ref>{{cite journal|last=Read|first=J.D.|title=The availability heuristic in person identification: The sometimes misleading consequences of enhanced contextual information|journal=Applied Cognitive Psychology|year=1995|volume=9|pages=91–121}}</ref> For example, many people think that the likelihood of dying from shark attacks is greater than that of dying from being hit by falling airplane parts when more people actually die from falling airplane parts.<ref>{{Cite web |title=Odds and ends - The San Diego Union-Tribune |url=http://legacy.sandiegouniontribune.com/uniontrib/20040222/news_mz1c22odds.html |url-status=dead |archive-url=https://web.archive.org/web/20190325193349/http://legacy.sandiegouniontribune.com/uniontrib/20040222/news_mz1c22odds.html |archive-date=2019-03-25 |website=legacy.sandiegouniontribune.com}}</ref> When a shark attack occurs, the deaths are widely reported in the media whereas deaths as a result of being hit by falling airplane parts are rarely reported in the media.<ref>{{Cite journal |last=Read |first=J.D. |year=1995 |title=The availability heuristic in person identification: The sometimes misleading consequences of enhanced contextual information |journal=Applied Cognitive Psychology |volume=9 |issue=2 |pages=91–121 |doi=10.1002/acp.2350090202}}</ref>


In a 2010 study exploring how vivid television portrayals are used when forming social reality judgments, people watching vivid violent media gave higher estimates of the prevalence of crime and police immorality in the real world than those not exposed to vivid television. These results suggest that television violence does in fact have a direct causal impact on participants' social reality beliefs. Repeated exposure to vivid violence leads to an increase in people's risk estimates about the prevalence of crime and violence in the real world.<ref>{{cite journal|last=riddle|first=Karen|title=Always on My Mind: Exploring How Frequent, Recent, and Vivid Television Portrayals Are Used in the Formation of Social Reality Judgments|journal=Media Psychology|year=2010|volume=13|pages=155–179|doi=10.1080/15213261003800140}}</ref> Counter to these findings, researchers from a similar study argued that these effects may be due to effects of new information. Researchers tested the new information effect by showing movies depicting dramatic risk events and measuring their risk assessment after the film. Contrary to previous research, there were no effects on risk perception due to exposure to dramatic movies.<ref>{{cite journal|last=Sjoberg|first=Lennart|coauthors=Engelberg, E.|title=Risk Perception and Movies: A Study of Availability as a Factor in Risk Perception|journal=Risk Analysis|year=2010|volume=30|issue=1|pages=95–106|doi=10.1111/j.1539-6924.2009.01335.x}}</ref> In a 2010 study exploring how vivid television portrayals are used when forming ] judgments, people watching vivid violent media gave higher estimates of the prevalence of crime and police immorality in the real world than those not exposed to vivid television. These results suggest that ] does in fact have a direct causal impact on participants' social reality beliefs. Repeated exposure to vivid violence leads to an increase in people's risk estimates about the prevalence of crime and violence in the real world.<ref>{{Cite journal |last=Riddle |first=Karen |year=2010 |title=Always on My Mind: Exploring How Frequent, Recent, and Vivid Television Portrayals Are Used in the Formation of Social Reality Judgments |journal=Media Psychology |volume=13 |issue=2 |pages=155–179 |doi=10.1080/15213261003800140 |s2cid=145074578}}</ref> Counter to these findings, researchers from a similar study argued that these effects may be due to effects of new information. Researchers tested the new information effect by showing movies depicting dramatic risk events and measuring their risk assessment after the film. Contrary to previous research, there were no long-term effects on risk perception due to exposure to dramatic movies. However, the study did find evidence of idiosyncratic effects of the movies - that is, people reacted immediately after the movies with enhanced or diminished risk beliefs, which faded after a period of 10 days.<ref name="SjöbergEngelberg2010">{{Cite journal |last1=Sjöberg |first1=Lennart |last2=Engelberg |first2=Elisabeth |year=2010 |title=Risk Perception and Movies: A Study of Availability as a Factor in Risk Perception |journal=Risk Analysis |volume=30 |issue=1 |pages=95–106 |doi=10.1111/j.1539-6924.2009.01335.x |issn=0272-4332 |pmid=20055978|bibcode=2010RiskA..30...95S |s2cid=10584667 }}</ref>

Another measurable effect is the inaccurate estimation of the fraction of deaths caused by terrorism compared to homicides with other causes.<ref></ref>


===Health=== ===Health===
Researchers examined the role of cognitive heuristics in the ] risk-assessment process. 331 physicians reported worry about on-the-job ] exposure, and experience with patients who have HIV. By analyzing answers to questionnaires handed out, researchers concluded that availability of AIDS information did not relate strongly to ].<ref name="HeathAcklin1991">{{Cite journal |last1=Heath |first1=Linda |last2=Acklin |first2=Marvin |last3=Wiley |first3=Katherine |year=1991 |title=Cognitive Heuristics and AIDS Risk Assessment Among Physicians |journal=Journal of Applied Social Psychology |volume=21 |issue=22 |pages=1859–1867 |doi=10.1111/j.1559-1816.1991.tb00509.x |issn=0021-9029}}</ref>
According to the department of Psychology at Nancy University France, studies have examined the impact of the availability heuristic in the perceptions of health-related events: lifetime risk of ], subjective life expectancy, and subjective age of onset of ].<ref name="gana" >{{cite journal|last=Gana|first=K|coauthors=Lourel, M., Trouillet, R., Fort, I., Mezred, D., Blaison, C., Boujemadi, V., K'Delant, P., Ledrich, J.|title=Judgment of riskiness: Impact of personality, naive theories and heuristic thinking among female students|journal=Psychology and Health|year=2010|volume=25|issue=2|pages=131–147|doi=10.1080/08870440802207975}}</ref> In each section, three conditions were set up: control, anchoring heuristic, and availability heuristic. The findings revealed that availability and anchoring were being used to estimate personal health-related events. Hypochondriac tendencies, optimism, depressive mood, subjective health, internal locus of control and recall of information had a significant impact on judgments of riskiness. Availability also impacted perceived health risks.<ref name="gana" />


Participants in a 1992 study read case descriptions of hypothetical patients who varied on their sex and sexual preference. These hypothetical patients showed symptoms that could have been caused by five different diseases (AIDS, leukemia, influenza, meningitis, or appendicitis). Participants were instructed to indicate which disease they thought the patient had and then they rated patient responsibility and interaction desirability. Consistent with the availability heuristic, either the more common (]) or the more publicized (AIDS) disease was chosen.<ref>{{Cite journal |last=Triplet |first=R.G |year=1992 |title=Discriminatory biases in the perception of illness: The application of availability and representativeness heuristics to the AIDS crisis |journal=Basic and Applied Social Psychology |volume=13 |issue=3 |pages=303–322 |doi=10.1207/s15324834basp1303_3}}</ref>
In another study, risk assessments of contracting breast cancer were based on experiences with an abnormal breast symptom, experiences with affected family members and friends.Researchers analyzed interviews from women talking about their own breast cancer risk. They found the availability, simulation, representativeness, affect, and perceived control heuristics, and search were most frequently used for making risk assessments.<ref>{{cite journal|last=Katapodi|first=M.C|coauthors=Facione, N.C., Humphreys, J.C., Dodd, M.J.|title=Perceived breast cancer risk: Heuristic reasoning and search for a dominance structure|journal=Social Science & Medicine|year=2005|volume=60|issue=2|pages=421–432}}</ref>


===Business and economy===
Researchers examined the role of cognitive heuristics in the ] risk-assessment process. 331 physicians reported worry about on-the-job ] exposure, and experience with patients who have HIV. They tested to see if participants used the availability heuristic by analyzing their response to questions about talking and reading about AIDS. Availability of AIDS information did not relate strongly to perceived risk. Availability was not significantly related to worry after variance associated with simulation and experience with AIDS was removed.<ref>{{cite journal|last=Heath|first=Linda|coauthors=Acklin, M., Wiley, K.|title=Cognitive heuristics and AIDS risk assessment among physicians|journal=Journal of Applied Social Psychology|year=1991|volume=21|issue=22|pages=1859–1867}}</ref>
One study sought to analyze the role of the availability heuristic in financial markets. Researchers defined and tested two aspects of the availability heuristic:<ref name="kliger">{{Cite journal |last1=Kliger |first1=Doron |last2=Kudryavtsev |first2=Andrey |year=2010 |title=The Availability Heuristic and Investors' Reaction to Company-Specific Events |journal=Journal of Behavioral Finance |volume=11 |issue=1 |pages=50–65 |doi=10.1080/15427561003591116 |issn=1542-7560 |s2cid=154727453}}</ref>


* Outcome Availability&nbsp;– availability of positive and negative investment outcomes, and
Participants in a 1992 study read case descriptions of hypothetical patients who varied on their sex and sexual preference. These hypothetical patients showed symptoms of two different diseases. Participants were instructed to indicate which disease they thought the patient had and then they rated patient responsibility and interactional desirability. Consistent with the availability heuristic, either the more common (]) or the more publicized (AIDS) disease was chosen.<ref>{{cite journal|last=Triplet|first=R.G|title=Discriminatory biases in the perception of illness: The application of availability and representativeness heuristics to the AIDS crisis|journal=Basic and Applied Social Psychology|year=1992|volume=13|issue=3|pages=303–322}}</ref>
* Risk Availability&nbsp;– availability of ].<ref name="kliger" />


On days of substantial ] moves, abnormal stock price reactions to upgrades are weaker, than those to downgrades. These availability effects are still significant even after controlling for event-specific and company-specific factors.<ref name="kliger" />
===Business and Economy===
One study sought to analyze the role of the availability heuristic in financial markets. Researchers defined and tested two aspects of the availability heuristic:<ref name="klinger">{{cite journal|last=Klinger|first=D|coauthors=Kudryavtsev, A.|title=The availability heuristic and investors' reactions to company-specific events|journal=The Journal of Behavioral Finance|year=2010|volume=11|issue=50-65|doi=10.1080/15427561003591116}}</ref>
*Outcome Availability&nbsp;– availability of positive and negative investment outcomes, and
*Risk Availability&nbsp;– availability of financial risk<ref name="klinger" />
Researchers tested the availability effect on investors' reactions to analyst recommendation revisions and found that positive stock price reactions to recommendation upgrades are stronger when accompanied by positive ] returns. On the other hand, negative stock price reactions to recommendation downgrades are stronger when accompanied by negative stock market index returns. On days of substantial stock market moves, abnormal stock price reactions to upgrades are weaker, and abnormal stock price reactions to downgrades are stronger. These availability effects are still significant even after controlling for event-specific and company-specific factors.<ref name="klinger" />


Similarly, research has pointed out that under the availability heuristic, humans are not reliable because they assess probabilities by giving more weight to current or easily recalled information instead of processing all relevant information. Since information regarding the current state of the economy is readily available, researchers attempted to expose the properties of business cycles to predict the availability bias in analysts' growth forecasts. They showed the availability heuristic to play a role in analysis of forecasts and influence investments because of this.<ref>{{cite journal|last=Lee|first=B|coauthors=O'Brien, J., Sivaramakrishnan, K.|title=An Analysis of Financial Analysts' Optimism in Long-term Growth Forecasts|journal=The Journal of Behavioral Finance|year=2008|volume=9|pages=171–184|doi=10.1080/15427560802341889}}</ref> Similarly, research has pointed out that under the availability heuristic, humans are not reliable because they assess probabilities by giving more weight to current or easily recalled information instead of processing all relevant information. Since information regarding the current state of the economy is readily available, researchers attempted to expose the properties of business cycles to predict the availability bias in analysts' growth forecasts. They showed the availability heuristic to play a role in analysis of forecasts and influence investments because of this.<ref name="LeeO">{{Cite journal |last1=Lee |first1=Byunghwan |last2=O'Brien |first2=John |last3=Sivaramakrishnan |first3=K. |year=2008 |title=An Analysis of Financial Analysts' Optimism in Long-term Growth Forecasts |journal=Journal of Behavioral Finance |volume=9 |issue=3 |pages=171–184 |doi=10.1080/15427560802341889 |issn=1542-7560 |s2cid=154169718}}</ref>


In effect, investors are using the availability heuristic to make decisions and subsequently, may be obstructing their own investment success. An investor's lingering perceptions of a dire market environment may be causing them to view investment opportunities through an overly negative lens, making it less appealing to consider taking on investment risk, no matter how small the returns on perceived "safe" investments. To illustrate, ]'s annual Global Investor Sentiment Survey 1 asked individuals how they believed the ] performed in 2009, 2010, and 2011. 66 percent of respondents stated that they believed the market was either flat or down in 2009, 48 percent said the same about 2010 and 53 percent also said the same about 2011. In reality, the S&P 500 saw 26.5 percent annual returns in 2009, 15.1 percent annual returns in 2010, and 2.1 percent annual returns in 2011, meaning lingering perceptions based on dramatic, painful events are impacting decision-making even when those events are over.<ref>{{Cite web |date=October 6, 2012 |title=Investors Should Beware The Role of 'Availability Bias' |url=http://www.businessinsider.com/the-availability-bias-is-driving-investor-decisions-2012-10 |access-date=December 1, 2013 |website=Business Insider}}</ref>
Additionally, a study by Hayibor and Wasieleski found that the availability of others who believe that a particular act is morally acceptable is positively related to others' perceptions of the morality of that act. This suggests that availability heuristic also has an effect on ] decision making and ethical behavior in organizations.<ref>{{cite journal|last=Hayibor|first=S|coauthors=Wasieleski, D.M.|title=Effects of the use of availability|journal=Journal of Business Ethics|year=2009|volume=84|pages=151–165|doi=10.1007/s10551-008-9690-7}}</ref>

Additionally, a study by Hayibor and Wasieleski found that the availability of others who believe that a particular act is morally acceptable is positively related to others' perceptions of the morality of that act. This suggests that availability heuristic also has an effect on ] ] and ethical behavior in organizations.<ref name="HayiborWasieleski2008">{{Cite journal |last1=Hayibor |first1=Sefa |last2=Wasieleski |first2=David M. |year=2008 |title=Effects of the Use of the Availability Heuristic on Ethical Decision-Making in Organizations |journal=Journal of Business Ethics |volume=84 |issue=S1 |pages=151–165 |doi=10.1007/s10551-008-9690-7 |issn=0167-4544 |s2cid=144947312}}</ref>


===Education=== ===Education===
A study done by Craig R. Fox provides an example of how availability heuristics can work in the classroom. In this study, Fox tests whether difficulty of recall influences judgment, specifically with course evaluations among college students. In his study he had two groups complete a course evaluation form. He asked the first group to write two recommended improvements for the course (a relatively easy task) and then write two positives about the class. The second group was asked to write ten suggestions where the professor could improve (a relatively difficult task) and then write two positive comments about the course. At the end of the evaluation both groups were asked to rate the course on a scale from one to seven. The results showed that students asked to write ten suggestions (difficult task) rated the course less harshly because it was more difficult for them to recall the information. Students asked to do the easier evaluation with only two complaints had less difficulty in terms of availability of information, so they rated the course more harshly.<ref>{{cite journal|last=Fox|first=Craig R.|title=The availability heuristic in the classroom: How soliciting more criticism can boost your course ratings|journal=Judgment and Decision Making |year=2006 |month=July |volume=1|issue=1|pages=86–90}}</ref> A study done by Craig R. Fox provides an example of how availability heuristics can work in the classroom. In this study, Fox tests whether the difficulty of recall influences judgment, specifically with course evaluations among college students. In his study he had two groups complete a course evaluation form. He asked the first group to write two recommended improvements for the course (a relatively easy task) and then write two positives about the class. The second group was asked to write ten suggestions where the professor could improve (a relatively difficult task) and then write two positive comments about the course. At the end of the evaluation, both groups were asked to rate the course on a scale from one to seven. The results showed that students asked to write ten suggestions (difficult task) rated the course less harshly because it was more difficult for them to recall the information. Most of the students in the group that was asked to fill in 10 suggestions didn't fill in more than two being unable to recall more instances where they were unsatisfied with the class. Students asked to do the easier evaluation with only two complaints had less difficulty in terms of availability of information, so they rated the course more harshly.<ref>{{Cite journal |last=Fox |first=Craig R. |year=2006 |title=The availability heuristic in the classroom: How soliciting more criticism can boost your course ratings |url=http://journal.sjdm.org/jdm06020.pdf |journal=Judgment and Decision Making |volume=1 |issue=1 |pages=86–90 |doi=10.1017/S1930297500000371 |s2cid=4466291 |issn=1930-2975}}</ref>


Another study by Marie Geurten sought to test the availability heuristic in young children. Children of varying ages (from 4 to 8 years old) were tasked with generating a list of names, with some being asked for a shorter list and some for a longer list. The study then assessed the children's own impressions of their ability to recall names. Those children who were tasked with generating a shorter list had a higher perception of their ability to recall names than those who were tasked with generating a longer list. According to the study, this suggests that the children based their assessment of their recall abilities on their subjective experience of ease of recall.<ref>{{Cite journal |last1=Geurten |first1=Marie |last2=Willems |first2=Sylvie |last3=Germain |first3=Sophie |last4=Meulemans |first4=Thierry |date=November 2015 |title=Less is more: The availability heuristic in early childhood |url=https://orbi.uliege.be/handle/2268/186448 |journal=British Journal of Developmental Psychology |language=en |volume=33 |issue=4 |pages=405–410 |doi=10.1111/bjdp.12114 |pmid=26332945 |hdl=2268/186448}}</ref>
===Criminal Justice===
The media usually focuses on violent or extreme cases, which are more readily available in the public's mind. This may come into play when it is time for the judicial system to evaluate and determine the proper punishment for a crime. In one study, respondents rated how much they agreed with hypothetical laws and policies such as "Would you support a law that required all offenders convicted of unarmed muggings to serve a minimum prison term of two years?" Participants then read cases and rated each case on several questions about punishment. As hypothesized, respondents recalled more easily from ] stories that contain severe harm, which seemed to influence their sentencing choices to make them push for harsher punishments. This can be eliminated by adding high concrete or high contextually distinct details into the crime stories about less severe injuries.<ref>{{cite journal|last=Stalans|first=L.J|title=Citizens' crime stereotypes, biased recall, and punishment preferences in abstract cases|journal=Law and Human Behavior|year=1993|volume=17|issue=451-469}}</ref>


===Criminal justice===
A similar study asked jurors and college students to choose sentences on four severe criminal cases in which prison was a possible but not an inevitable sentencing outcome. Respondents answering questions about court performance on a public opinion formulated a picture of what the courts do and then evaluated the appropriateness of that behavior. Respondents recalled from public information about crime and sentencing. This type of information is incomplete because the news media present a highly selective and non-] selection of crime, focusing on the violent and extreme, rather than the ordinary. This makes most people think that judges are too lenient. But, when asked to choose the punishments, the sentences given by students were equal to or less severe than those given by judges. In other words, the availability heuristic made people believe that judges and jurors were too lenient in the courtroom, but the participants gave similar sentences when placed in the position of the judge, suggesting that the information they recalled was not correct.<ref>{{cite journal|last=Diamond|first=S.S|coauthors=Stalans, L.J|title=The myth of judicial leniency in sentencing|journal=Behavioral Sciences & the Law|year=1989|volume=7|pages=73–89}}</ref>
The media usually focuses on violent or extreme cases, which are more readily available in the public's mind. This may come into play when it is time for the judicial system to evaluate and determine the proper punishment for a crime. In one study, respondents rated how much they agreed with hypothetical laws and policies such as "Would you support a law that required all offenders convicted of unarmed muggings to serve a minimum prison term of two years?" Participants then read cases and rated each case on several questions about punishment. As hypothesized, respondents recalled more easily from ] stories that contain severe harm, which seemed to influence their sentencing choices to make them push for harsher punishments. This can be eliminated by adding high concrete or high contextually distinct details into the crime stories about less severe injuries.<ref name="Stalans1993">{{Cite journal |last=Stalans |first=Loretta J. |year=1993 |title=Citizens' crime stereotypes, biased recall, and punishment preferences in abstract cases: The educative role of interpersonal sources. |journal=Law and Human Behavior |volume=17 |issue=4 |pages=451–470 |doi=10.1007/BF01044378 |issn=1573-661X |s2cid=142611246}}</ref>


A similar study asked jurors and college students to choose sentences on four severe criminal cases in which prison was a possible but not an inevitable sentencing outcome. Respondents answering questions about court performance on a public opinion formulated a picture of what the courts do and then evaluated the appropriateness of that behavior. Respondents recalled public information about crime and sentencing. This type of information is incomplete because the news media present a highly selective and non-] selection of crime, focusing on the violent and extreme, rather than the ordinary. This makes most people think that judges are too lenient. But, when asked to choose the punishments, the sentences given by students were equal to or less severe than those given by judges. In other words, the availability heuristic made people believe that judges and jurors were too lenient in the courtroom, but the participants gave similar sentences when placed in the position of the judge, suggesting that the information they recalled was not correct.<ref name="DiamondStalans1989">{{Cite journal |last1=Diamond |first1=Shari Seidman |last2=Stalans |first2=Loretta J. |year=1989 |title=The myth of judicial leniency in sentencing |journal=Behavioral Sciences & the Law |volume=7 |issue=1 |pages=73–89 |doi=10.1002/bsl.2370070106 |issn=0735-3936}}</ref>
Researchers in 1989 predicted that mock jurors would rate a witness to be '''more''' deceptive if the witness testified truthfully ''before'' lying than when the witness was caught lying first before telling the truth. If the availability heuristic played a role in this, lying second would remain in jurors' minds (since it was more recent) and they would most likely remember the witness lying over the truthfulness. To test the hypothesis, 312 university students played the roles of mock jurors and watched a videotape of a witness presenting testimony during a trial. Results confirmed the hypothesis, as mock jurors were most influenced by the most recent act.<ref>{{cite journal|last=DeTurck|first=M.A|coauthors=Texter, L.A., Harszlak, J.J.|title=Effects of information processing objectives on judgments of deception following perjury|journal=Communication Research|year=1989|volume=16|issue=3|pages=434–452}}</ref>


Researchers in 1989 predicted that mock jurors would rate a witness to be ''more'' deceptive if the witness testified truthfully ''before'' lying than when the witness was caught lying first before telling the truth. If the availability heuristic played a role in this, lying second would remain in jurors' minds (since it was more recent) and they would most likely remember the witness lying over the truthfulness. To test the hypothesis, 312 university students played the roles of mock jurors and watched a videotape of a witness presenting testimony during a trial. Results confirmed the hypothesis, as mock jurors were most influenced by the most recent act.<ref name="deTurckTexter1989">{{Cite journal |last1=deTurck |first1=M. A. |last2=Texter |first2=L. A. |last3=Harszlak |first3=J. J. |year=1989 |title=Effects of Information Processing Objectives on Judgments of Deception Following Perjury |journal=Communication Research |volume=16 |issue=3 |pages=434–452 |doi=10.1177/009365089016003006 |issn=0093-6502 |s2cid=145495112}}</ref>
==Critiques==


===Perceived risk===
Some researchers have suggested that perceived causes or reasons for an event, rather than imagery of the event itself, influence probability estimates.<ref name="levi">{{cite journal|last=Levi|first=A|coauthors=Pryor, J.B.|title=Use of the availability heuristic in probability estimates of future events: The effects of imagining outcomes versus imagining reasons|journal=Organizational Behavior & Human Performance|year=1987|volume=40|issue=2}}</ref> Evidence for this notion stems from a study where participants either imagined the winner of the debate, or came up with reasons for why ] or ] would win the 1984 U.S. Presidential Candidate debate. The results of this study explained that imagining Reagan or Mondale winning the debate had no effect on predictions of who would win the debate. However, imagining and considering reasons for why Reagan or Mondale would win the debate did significantly affect predictions.<ref name="levi"/>
{{see|Perceived risk}}
Previous studies have indicated that explaining a hypothetical event makes the event seem more likely through the creation of causal connections. However, such effects could arise through the use of the availability heuristic; that is, subjective likelihood is increased by an event becoming easier to imagine.<ref name="Carroll1978">{{Cite journal |last=Carroll |first=John S. |year=1978 |title=The effect of imagining an event on expectations for the event: An interpretation in terms of the availability heuristic |journal=Journal of Experimental Social Psychology |volume=14 |issue=1 |pages=88–96 |doi=10.1016/0022-1031(78)90062-8 |issn=0022-1031}}</ref>


A study done asked those participating to pick between two illnesses. Those doing the study wanted to know which disease they thought was more likely to cause death. In the study, they asked participants to choose between a stroke and asthma as to which one someone was more likely to die from. The researchers concluded that it depended on what experiences were available to them. If they knew someone or heard of someone that died from one of the diseases that is the one they perceived to be a higher risk to die from.<ref>{{Cite journal |last1=Pachur |first1=Thorsten |last2=Hertwig |first2=Ralph |last3=Steinmann |first3=Florian |date=2012 |title=How do people judge risks: Availability heuristic, affect heuristic, or both? |journal=Journal of Experimental Psychology: Applied |language=en |volume=18 |issue=3 |pages=314–330 |doi=10.1037/a0028279 |issn=1939-2192 |pmid=22564084 |hdl-access=free |hdl=11858/00-001M-0000-0024-F052-7}}</ref>
Other psychologists argue that the classic studies on the availability heuristic are vague and do not explain the underlying processes.<ref name="wanke">{{cite journal|last=Wanke|first=M|coauthors=Schwarz, N., Bless, H.|title=The availability heuristic revisited: Experienced ease of retrieval in mundane frequency estimates|journal=Acta Psychologica|year=1995|volume=89|pages=83–90}}</ref> For example, in the famous Tversky and Kahneman study, Wanke et al. believe that this differential ease of recall, may alter subjects' frequency estimates in two different ways. In one way, as the availability heuristic suggests, the subjects may use the subjective experience of ease or difficulty of recall as a basis of judgment. Researchers also assert that if this is done, they would predict a higher frequency if the recall task is experienced as easy rather than difficult. In a contrasting scenario, researchers suggest that the subjects may recall as many words of each type as possible within the time given to them and may base their judgment on the recalled sample of words. If it is easier to recall words which begin with a certain letter, these words would be over-represented in the recalled sample, again producing a prediction of higher frequency. In the second scenario the estimate would be based on recalled content rather than on the subjective experience of ease of recall.<ref name="wanke"/>


===Vividness effects===
Some researchers have shown concern about confounding variables in the original Tversky and Kahneman study.<ref name="schwarz" /> Researchers question if the participants recalling celebrity names were basing frequency estimates on the amount of content recalled or on the ease of recall. Some researchers suggest that the design of the earlier experiment was flawed and did not actually determine how the availability heuristic works.<ref name="schwarz" />
Two studies with 108 undergraduates investigated vivid information and its impact on social judgment and the availability heuristic and its role in mediating vividness effects.


In study 1, Subjects listened to a tape recording that described a woman who lived with her 7-year-old son. Subjects then heard arguments about the woman's fitness as a parent and were asked to draw their own conclusions regarding her fitness or unfitness. The concrete and colorful language were found to influence judgments about the woman's fitness as a mother.
Recent research has provided some evidence that the availability heuristic is only one of many strategies involved in frequency judgment.<ref>{{cite journal|last=Hulme|first=C|coauthors=Roodenrys, S., Brown, G., Mercer, R.|title=The role of long-term memory mechanisms in memory span|journal=British Journal of Psychology|year=1995|volume=86|issue=4|pages=527–536|doi=10.1111/j.2044-8295.1995.tb02570.x}}</ref> Future research should attempt to incorporate all these factors.

In study 2, a series of male and female names were presented to subjects; for each name, subjects were told the university affiliation of the individual (Yale or Stanford). When some names were presented, subjects were simultaneously shown a photograph that purportedly portrayed the named individual. Subsequently, to assess what subjects could remember (as a measure of availability), each name was represented, as well as the appropriate photograph if one had been originally presented. The study considered whether the display or non-display of photographs biased subjects' estimates as to the percentage of Yale (vs Stanford) students in the sample of men and women whose names appeared on the original list, and whether these estimated percentages were causally related to the respondents' memory for the college affiliations of the individual students on the list. The presence of photographs affected judgments about the proportion of male and female students at the two universities. Such effects have typically been attributed to the ready accessibility of vividly presented information in memory—that is, to the availability heuristic.

In both studies, vividness affected both availability (ability to recall) and judgments. However, causal modeling results indicated that the availability heuristic did not play a role in the judgment process.<ref name="ShedlerManis1986">{{Cite journal |last1=Shedler |first1=Jonathan |last2=Manis |first2=Melvin |year=1986 |title=Can the availability heuristic explain vividness effects? |journal=Journal of Personality and Social Psychology |volume=51 |issue=1 |pages=26–36 |doi=10.1037/0022-3514.51.1.26 |issn=1939-1315}}</ref>

===Judging frequency and probability===
In general, availability is correlated with ecological frequency, but it is also affected by other factors. Consequently, the reliance on the availability heuristic leads to systematic biases. Such biases are demonstrated in the judged frequency of classes of words, of combinatoric outcomes, and of repeated events. The phenomenon of ] is explained as an availability bias.<ref name="tversky" />

In the original Tversky and Kahneman (1973) research, three major factors that are discussed are the frequency of repetition, frequency of co-occurrence, and illusory correlation. The use of frequency of repetition aids in the retrieval of relevant instances. The idea behind this phenomenon is that the more an instance is repeated within a category or list, the stronger the link between the two instances becomes. Individuals then use the strong association between the instances to determine the frequency of an instance. Consequently, the association between the category or list and the specific instance often influences frequency judgement. Frequency of co-occurrence strongly relates to Frequency of repetition, such that the more an item-pair is repeated, the stronger the association between the two items becomes, leading to a bias when estimating the frequency of co-occurrence. Due to the phenomena of frequency of co-occurrence, illusory correlations also often play a big role.<ref name="tversky" />

Another factor that affects the availability heuristic in frequency and probability is exemplars. Exemplars are the typical examples that stand out during the process of recall. If asked what participants thought different set sizes were (how many men and how many women are in the class), participants would use exemplars to determine the size of each set. Participants would derive their answers on ease of recall of the names that stood out. Participants read a list of names of members of a class for 30 seconds, and then participants were asked the male to female ratio of the class. The participant's answer would depend on the recall of exemplars. If the participant reading the list recalled seeing more common male names, such as Jack, but the only female names in the class were uncommon names, such as Deepika, then the participant will recall that there were more men than women. The opposite would be true if there were more common female names on the list and uncommon male names. Due to the availability heuristic, names that are more easily available are more likely to be recalled, and can thus alter judgments of probability.<ref name="ReferenceA">{{Cite journal |last1=Manis |first1=Melvin |last2=Jonides |first2=Jonathan |last3=Shedler |first3=John |last4=Nelson |first4=Thomas |date=1993 |title=Availability Heuristic in Judgments of Set Size and Frequency of Occurrence |journal=Journal of Personality & Social Psychology |volume=65 |issue=3 |pages=448–457 |doi=10.1037/0022-3514.65.3.448}}</ref>

Another example of the availability heuristic and exemplars would be seeing a shark in the ocean. Seeing a shark has a greater impact on an individual's memory than seeing a dolphin. If someone sees both sharks and dolphins in the ocean, they will be less aware of seeing the dolphins, because the dolphins had less of an impact on their memory. Due to the greater impact of seeing a shark, the availability heuristic can influence the probability judgement of the ratio of sharks and dolphins in the water. Thus, an individual who saw both a shark and a dolphin would assume a higher ratio of sharks in the water, even if there are more dolphins in reality.<ref name="ReferenceA" />

==Critiques==

=== Ease of recall as a critique ===
One of the earliest and most powerful critiques of the original Tversky and Kahneman<ref name="TverskyKahneman1974">{{Cite journal |last1=Tversky |first1=A. |last2=Kahneman |first2=D. |year=1974 |title=Judgment under Uncertainty: Heuristics and Biases |journal=Science |volume=185 |issue=4157 |pages=1124–1131 |bibcode=1974Sci...185.1124T |doi=10.1126/science.185.4157.1124 |issn=0036-8075 |pmid=17835457 |s2cid=143452957}}</ref> study on the availability heuristic was the Schwarz et al.<ref name="schwarz" /> study which found that the ease of recall was a key component in determining whether a concept became available. Many studies since this criticism of the original availability heuristic model have repeated this initial criticism, that the ease of recall factor became an integral facet of the availability heuristic itself (see Research section).

=== Alternative explanations ===
Much of the criticism against the availability heuristic has claimed that making use of the content that becomes available in our mind is not based on the ease of recall as suggested by Schwarz et al.<ref name="schwarz" /> For example, it could be argued that recalling more words that begin with K than words with the third letter being K could arise from how we categorize and process words into our memory. If we categorize words by the first letter and recall them through the same process, this would show more support for the representative heuristic than the availability heuristic. Based on the possibility of explanations such as these, some researchers have claimed that the classic studies on the availability heuristic are too vague in that they fail to account for people's underlying mental processes. Indeed, a study conducted by Wanke et al. demonstrated this scenario can occur in situations used to test the availability heuristic.<ref name="wanke">{{Cite journal |last1=Wänke |first1=Michaela |last2=Schwarz |first2=Norbert |last3=Bless |first3=Herbert |year=1995 |title=The availability heuristic revisited: Experienced ease of retrieval in mundane frequency estimates |journal=Acta Psychologica |volume=89 |issue=1 |pages=83–90 |doi=10.1016/0001-6918(93)E0072-A |issn=0001-6918}}</ref>

A second line of study has shown that frequency estimation may not be the only strategy we use when making frequency judgments. A recent line of research has shown that our situational working memory can access long-term memories, and this memory retrieval process includes the ability to determine more accurate probabilities.<ref name="HulmeRoodenrys1995">{{Cite journal |last1=Hulme |first1=Charles |last2=Roodenrys |first2=Steven |last3=Brown |first3=Gordon |last4=Mercer |first4=Robin |year=1995 |title=The role of long-term memory mechanisms in memory span |journal=British Journal of Psychology |volume=86 |issue=4 |pages=527–536 |doi=10.1111/j.2044-8295.1995.tb02570.x |issn=0007-1269}}</ref>


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Latest revision as of 21:29, 14 November 2024

Bias towards recently acquired information

The availability heuristic, also known as availability bias, is a mental shortcut that relies on immediate examples that come to a given person's mind when evaluating a specific topic, concept, method, or decision. This heuristic, operating on the notion that, if something can be recalled, it must be important, or at least more important than alternative solutions not as readily recalled, is inherently biased toward recently acquired information.

The mental availability of an action's consequences is positively related to those consequences' perceived magnitude. In other words, the easier it is to recall the consequences of something, the greater those consequences are often perceived to be. Most notably, people often rely on the content of their recall if its implications are not called into question by the difficulty they have in recalling it.

Overview and history

Kahneman's research established that common human errors can arise from heuristics and biases.

In the late 1960s and early 1970s, Amos Tversky and Daniel Kahneman began work on a series of papers examining "heuristic and biases" used in judgment under uncertainty. Prior to that, the predominant view in the field of human judgment was that humans are rational actors. Kahneman and Tversky explained that judgment under uncertainty often relies on a limited number of simplifying heuristics rather than extensive algorithmic processing. Soon, this idea spread beyond academic psychology, into law, medicine, and political science. This research questioned the descriptive adequacy of idealized models of judgment, and offered insights into the cognitive processes that explained human error without invoking motivated irrationality. One simplifying strategy people may rely on is the tendency to make a judgment about the frequency of an event based on how many similar instances are brought to mind. In 1973, Amos Tversky and Daniel Kahneman first studied this phenomenon and labeled it the "availability heuristic". An availability heuristic is a mental shortcut that relies on immediate examples that come to a given person's mind when evaluating a specific topic, concept, method, or decision. As follows, people tend to use a readily available fact to base their beliefs on a comparably distant concept. There has been much research done with this heuristic, but studies on the issue are still questionable with regard to the underlying process. Studies illustrate that manipulations intended to increase the subjective experience of ease of recall are also likely to affect the amount of recall. Furthermore, this makes it difficult to determine whether the obtained estimates of frequency, likelihood, or typicality are based on participants' phenomenal experiences or on a biased sample of recalled information.

However, some textbooks have chosen the latter interpretation introducing the availability heuristic as "one's judgments are always based on what comes to mind". For example, if a person is asked whether there are more words in the English language that start with a k or have k as the third letter, the person will probably be able to think of more words that begin with the letter k, concluding incorrectly that k is more frequent as the first letter than the third. In this Misplaced Pages article itself, for example, there are multiple instances of words such as "likely", "make", "take", "ask" and indeed "Misplaced Pages", but (aside from names) only a couple of initial K's: "know" and "key".

Research

Chapman (1967) described a bias in the judgment of the frequency with which two events co-occur. This demonstration showed that the co-occurrence of paired stimuli resulted in participants overestimating the frequency of the pairings. To test this idea, participants were given information about several hypothetical mental patients. The data for each patient consisted of a clinical diagnosis and a drawing made by the patient. Later, participants estimated the frequency with which each diagnosis had been accompanied by various features of the drawing. The subjects vastly overestimated the frequency of this co-occurrence (such as suspiciousness and peculiar eyes). This effect was labeled the illusory correlation. Tversky and Kahneman suggested that availability provides a natural account for the illusory-correlation effect. The strength of the association between two events could provide the basis for the judgment of how frequently the two events co-occur. When the association is strong, it becomes more likely to conclude that the events have been paired frequently. Strong associations will be thought of as having occurred together frequently.

In Tversky & Kahneman's first examination of availability heuristics, subjects were asked, "If a random word is taken from an English text, is it more likely that the word starts with a K, or that K is the third letter?" They argue that English-speaking people would immediately think of many words that begin with the letter "K" (kangaroo, kitchen, kale), but that it would take a more concentrated effort to think of any words in which "K" is the third letter (acknowledge, ask). Results indicated that participants overestimated the number of words that began with the letter "K" and underestimated the number of words that had "K" as the third letter. Tversky and Kahneman concluded that people answer questions like these by comparing the availability of the two categories and assessing how easily they can recall these instances. In other words, it is easier to think of words that begin with "K", more than words with "K" as the third letter. Thus, people judge words beginning with a "K" to be a more common occurrence. In reality, however, a typical text contains twice as many words that have "K" as the third letter than "K" as the first letter.

In Tversky and Kahneman's seminal paper, they include findings from several other studies, which also show support for the availability heuristic. Apart from their findings in the "K" study, they also found:

When participants were shown two visual structures and asked to pick the structure that had more paths, participants saw more paths in the structure that had more obvious available paths. In the structure that participants chose, there were more columns and shorter obvious paths, making it more available to them. When participants were asked to complete tasks involving estimation, they would often underestimate the end result. Participants were basing their final estimation on a quick first impression of the problem. Participants particularly struggled when the problems consisted of multiple steps. This occurred because participants were basing their estimation on an initial impression. Participants failed to account for the high rate of growth in the later steps due to the impression they formed in the initial steps. This was shown again in a task that asked participants to estimate the answer to a multiplication task, in which the numbers were presented as either 1x2x3x4x5x6x7x8 or 8x7x6x5x4x3x2x1. Participants who were presented the equation with the larger numbers first (8x7x6...), estimated a significantly higher result than participants with the lower numbers first (1x2x3...). Participants were given a short amount of time to make the estimation, thus participants based their estimates off of what was easily available, which in this case was the first few numbers in the sequence.

Explanations

Many researchers have attempted to identify the psychological process which creates the availability heuristic.

Tversky and Kahneman argue that the number of examples recalled from memory is used to infer the frequency with which such instances occur. In an experiment to test this explanation, participants listened to lists of names containing either 19 famous women and 20 less famous men or 19 famous men and 20 less famous women. Subsequently, some participants were asked to recall as many names as possible whereas others were asked to estimate whether male or female names were more frequent on the list. The names of the famous celebrities were recalled more frequently compared to those of the less famous celebrities. The majority of the participants incorrectly judged that the gender associated with more famous names had been presented more often than the gender associated with less famous names. Tversky and Kahneman argue that although the availability heuristic is an effective strategy in many situations when judging probability, use of this heuristic can lead to predictable patterns of errors.

Schwarz and his colleagues, on the other hand, proposed the ease of retrieval explanation, wherein the ease with which examples come to mind, not the number of examples, is used to infer the frequency of a given class. In a study by Schwarz and colleagues to test their explanation, participants were asked to recall either six or twelve examples of their assertive or very unassertive behavior. Participants were later asked to rate their own assertiveness. Pretesting had indicated that although most participants were capable of generating twelve examples, this was a difficult task. The results indicated that participants rated themselves as more assertive after describing six examples of assertive compared with unassertive behavior, but rated themselves as less assertive after describing twelve examples of assertive compared with unassertive behavior. The study reflected that the extent to which recalled content impacted judgment was determined by the ease with which the content could be brought to mind (it was easier to recall 6 examples than 12), rather than the amount of content brought to mind.

Research by Vaughn (1999) looked at the effects of uncertainty on the use of the availability heuristic. College students were asked to list either three or eight different study methods they could use in order to get an A on their final exams. The researchers also manipulated the time during the semester they would ask the students to complete the questionnaire. Approximately half of the participants were asked for their study methods during the third week of classes, and the other half were asked on the last day of classes. Next, participants were asked to rate how likely they would be to get an A in their easiest and hardest classes. Participants were then asked to rank the difficulty they experienced in recalling the examples they had previously listed. The researchers hypothesized that students would use the availability heuristic, based on the number of study methods they listed, to predict their grade only when asked at the beginning of the semester and about their hardest final. Students were not expected to use the availability heuristic to predict their grades at the end of the semester or about their easiest final. The researchers predicted this use of the availability heuristic because participants would be uncertain about their performance throughout the semester. The results indicated that students used the availability heuristic, based on the ease of recall of the study methods they listed, to predict their performance when asked at the beginning of the semester and about their hardest final. If the student listed only three study methods, they predicted a higher grade at the end of the semester only on their hardest final. If students listed eight study methods, they had a harder time recalling the methods and thus predicted a lower final grade on their hardest final. The results were not seen in the easy final condition because the students were certain they would get an A, regardless of the study method. The results supported this hypothesis and gave evidence to the fact that levels of uncertainty affect the use of the availability heuristic.

Applications

Media

After seeing news stories about child abductions, people may judge that the likelihood of this event is greater. 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 "newsworthy" events as more likely because they can more readily recall an example from memory. Moreover, unusual and vivid events like homicides, shark attacks, or lightning are more often reported in mass media than common and un-sensational causes of death like common diseases.

For example, many people think that the likelihood of dying from shark attacks is greater than that of dying from being hit by falling airplane parts when more people actually die from falling airplane parts. When a shark attack occurs, the deaths are widely reported in the media whereas deaths as a result of being hit by falling airplane parts are rarely reported in the media.

In a 2010 study exploring how vivid television portrayals are used when forming social reality judgments, people watching vivid violent media gave higher estimates of the prevalence of crime and police immorality in the real world than those not exposed to vivid television. These results suggest that television violence does in fact have a direct causal impact on participants' social reality beliefs. Repeated exposure to vivid violence leads to an increase in people's risk estimates about the prevalence of crime and violence in the real world. Counter to these findings, researchers from a similar study argued that these effects may be due to effects of new information. Researchers tested the new information effect by showing movies depicting dramatic risk events and measuring their risk assessment after the film. Contrary to previous research, there were no long-term effects on risk perception due to exposure to dramatic movies. However, the study did find evidence of idiosyncratic effects of the movies - that is, people reacted immediately after the movies with enhanced or diminished risk beliefs, which faded after a period of 10 days.

Another measurable effect is the inaccurate estimation of the fraction of deaths caused by terrorism compared to homicides with other causes.

Health

Researchers examined the role of cognitive heuristics in the AIDS risk-assessment process. 331 physicians reported worry about on-the-job HIV exposure, and experience with patients who have HIV. By analyzing answers to questionnaires handed out, researchers concluded that availability of AIDS information did not relate strongly to perceived risk.

Participants in a 1992 study read case descriptions of hypothetical patients who varied on their sex and sexual preference. These hypothetical patients showed symptoms that could have been caused by five different diseases (AIDS, leukemia, influenza, meningitis, or appendicitis). Participants were instructed to indicate which disease they thought the patient had and then they rated patient responsibility and interaction desirability. Consistent with the availability heuristic, either the more common (influenza) or the more publicized (AIDS) disease was chosen.

Business and economy

One study sought to analyze the role of the availability heuristic in financial markets. Researchers defined and tested two aspects of the availability heuristic:

  • Outcome Availability – availability of positive and negative investment outcomes, and
  • Risk Availability – availability of financial risk.

On days of substantial stock market moves, abnormal stock price reactions to upgrades are weaker, than those to downgrades. These availability effects are still significant even after controlling for event-specific and company-specific factors.

Similarly, research has pointed out that under the availability heuristic, humans are not reliable because they assess probabilities by giving more weight to current or easily recalled information instead of processing all relevant information. Since information regarding the current state of the economy is readily available, researchers attempted to expose the properties of business cycles to predict the availability bias in analysts' growth forecasts. They showed the availability heuristic to play a role in analysis of forecasts and influence investments because of this.

In effect, investors are using the availability heuristic to make decisions and subsequently, may be obstructing their own investment success. An investor's lingering perceptions of a dire market environment may be causing them to view investment opportunities through an overly negative lens, making it less appealing to consider taking on investment risk, no matter how small the returns on perceived "safe" investments. To illustrate, Franklin Templeton's annual Global Investor Sentiment Survey 1 asked individuals how they believed the S&P 500 Index performed in 2009, 2010, and 2011. 66 percent of respondents stated that they believed the market was either flat or down in 2009, 48 percent said the same about 2010 and 53 percent also said the same about 2011. In reality, the S&P 500 saw 26.5 percent annual returns in 2009, 15.1 percent annual returns in 2010, and 2.1 percent annual returns in 2011, meaning lingering perceptions based on dramatic, painful events are impacting decision-making even when those events are over.

Additionally, a study by Hayibor and Wasieleski found that the availability of others who believe that a particular act is morally acceptable is positively related to others' perceptions of the morality of that act. This suggests that availability heuristic also has an effect on ethical decision making and ethical behavior in organizations.

Education

A study done by Craig R. Fox provides an example of how availability heuristics can work in the classroom. In this study, Fox tests whether the difficulty of recall influences judgment, specifically with course evaluations among college students. In his study he had two groups complete a course evaluation form. He asked the first group to write two recommended improvements for the course (a relatively easy task) and then write two positives about the class. The second group was asked to write ten suggestions where the professor could improve (a relatively difficult task) and then write two positive comments about the course. At the end of the evaluation, both groups were asked to rate the course on a scale from one to seven. The results showed that students asked to write ten suggestions (difficult task) rated the course less harshly because it was more difficult for them to recall the information. Most of the students in the group that was asked to fill in 10 suggestions didn't fill in more than two being unable to recall more instances where they were unsatisfied with the class. Students asked to do the easier evaluation with only two complaints had less difficulty in terms of availability of information, so they rated the course more harshly.

Another study by Marie Geurten sought to test the availability heuristic in young children. Children of varying ages (from 4 to 8 years old) were tasked with generating a list of names, with some being asked for a shorter list and some for a longer list. The study then assessed the children's own impressions of their ability to recall names. Those children who were tasked with generating a shorter list had a higher perception of their ability to recall names than those who were tasked with generating a longer list. According to the study, this suggests that the children based their assessment of their recall abilities on their subjective experience of ease of recall.

Criminal justice

The media usually focuses on violent or extreme cases, which are more readily available in the public's mind. This may come into play when it is time for the judicial system to evaluate and determine the proper punishment for a crime. In one study, respondents rated how much they agreed with hypothetical laws and policies such as "Would you support a law that required all offenders convicted of unarmed muggings to serve a minimum prison term of two years?" Participants then read cases and rated each case on several questions about punishment. As hypothesized, respondents recalled more easily from long-term memory stories that contain severe harm, which seemed to influence their sentencing choices to make them push for harsher punishments. This can be eliminated by adding high concrete or high contextually distinct details into the crime stories about less severe injuries.

A similar study asked jurors and college students to choose sentences on four severe criminal cases in which prison was a possible but not an inevitable sentencing outcome. Respondents answering questions about court performance on a public opinion formulated a picture of what the courts do and then evaluated the appropriateness of that behavior. Respondents recalled public information about crime and sentencing. This type of information is incomplete because the news media present a highly selective and non-representative selection of crime, focusing on the violent and extreme, rather than the ordinary. This makes most people think that judges are too lenient. But, when asked to choose the punishments, the sentences given by students were equal to or less severe than those given by judges. In other words, the availability heuristic made people believe that judges and jurors were too lenient in the courtroom, but the participants gave similar sentences when placed in the position of the judge, suggesting that the information they recalled was not correct.

Researchers in 1989 predicted that mock jurors would rate a witness to be more deceptive if the witness testified truthfully before lying than when the witness was caught lying first before telling the truth. If the availability heuristic played a role in this, lying second would remain in jurors' minds (since it was more recent) and they would most likely remember the witness lying over the truthfulness. To test the hypothesis, 312 university students played the roles of mock jurors and watched a videotape of a witness presenting testimony during a trial. Results confirmed the hypothesis, as mock jurors were most influenced by the most recent act.

Perceived risk

Further information: Perceived risk

Previous studies have indicated that explaining a hypothetical event makes the event seem more likely through the creation of causal connections. However, such effects could arise through the use of the availability heuristic; that is, subjective likelihood is increased by an event becoming easier to imagine.

A study done asked those participating to pick between two illnesses. Those doing the study wanted to know which disease they thought was more likely to cause death. In the study, they asked participants to choose between a stroke and asthma as to which one someone was more likely to die from. The researchers concluded that it depended on what experiences were available to them. If they knew someone or heard of someone that died from one of the diseases that is the one they perceived to be a higher risk to die from.

Vividness effects

Two studies with 108 undergraduates investigated vivid information and its impact on social judgment and the availability heuristic and its role in mediating vividness effects.

In study 1, Subjects listened to a tape recording that described a woman who lived with her 7-year-old son. Subjects then heard arguments about the woman's fitness as a parent and were asked to draw their own conclusions regarding her fitness or unfitness. The concrete and colorful language were found to influence judgments about the woman's fitness as a mother.

In study 2, a series of male and female names were presented to subjects; for each name, subjects were told the university affiliation of the individual (Yale or Stanford). When some names were presented, subjects were simultaneously shown a photograph that purportedly portrayed the named individual. Subsequently, to assess what subjects could remember (as a measure of availability), each name was represented, as well as the appropriate photograph if one had been originally presented. The study considered whether the display or non-display of photographs biased subjects' estimates as to the percentage of Yale (vs Stanford) students in the sample of men and women whose names appeared on the original list, and whether these estimated percentages were causally related to the respondents' memory for the college affiliations of the individual students on the list. The presence of photographs affected judgments about the proportion of male and female students at the two universities. Such effects have typically been attributed to the ready accessibility of vividly presented information in memory—that is, to the availability heuristic.

In both studies, vividness affected both availability (ability to recall) and judgments. However, causal modeling results indicated that the availability heuristic did not play a role in the judgment process.

Judging frequency and probability

In general, availability is correlated with ecological frequency, but it is also affected by other factors. Consequently, the reliance on the availability heuristic leads to systematic biases. Such biases are demonstrated in the judged frequency of classes of words, of combinatoric outcomes, and of repeated events. The phenomenon of illusory correlation is explained as an availability bias.

In the original Tversky and Kahneman (1973) research, three major factors that are discussed are the frequency of repetition, frequency of co-occurrence, and illusory correlation. The use of frequency of repetition aids in the retrieval of relevant instances. The idea behind this phenomenon is that the more an instance is repeated within a category or list, the stronger the link between the two instances becomes. Individuals then use the strong association between the instances to determine the frequency of an instance. Consequently, the association between the category or list and the specific instance often influences frequency judgement. Frequency of co-occurrence strongly relates to Frequency of repetition, such that the more an item-pair is repeated, the stronger the association between the two items becomes, leading to a bias when estimating the frequency of co-occurrence. Due to the phenomena of frequency of co-occurrence, illusory correlations also often play a big role.

Another factor that affects the availability heuristic in frequency and probability is exemplars. Exemplars are the typical examples that stand out during the process of recall. If asked what participants thought different set sizes were (how many men and how many women are in the class), participants would use exemplars to determine the size of each set. Participants would derive their answers on ease of recall of the names that stood out. Participants read a list of names of members of a class for 30 seconds, and then participants were asked the male to female ratio of the class. The participant's answer would depend on the recall of exemplars. If the participant reading the list recalled seeing more common male names, such as Jack, but the only female names in the class were uncommon names, such as Deepika, then the participant will recall that there were more men than women. The opposite would be true if there were more common female names on the list and uncommon male names. Due to the availability heuristic, names that are more easily available are more likely to be recalled, and can thus alter judgments of probability.

Another example of the availability heuristic and exemplars would be seeing a shark in the ocean. Seeing a shark has a greater impact on an individual's memory than seeing a dolphin. If someone sees both sharks and dolphins in the ocean, they will be less aware of seeing the dolphins, because the dolphins had less of an impact on their memory. Due to the greater impact of seeing a shark, the availability heuristic can influence the probability judgement of the ratio of sharks and dolphins in the water. Thus, an individual who saw both a shark and a dolphin would assume a higher ratio of sharks in the water, even if there are more dolphins in reality.

Critiques

Ease of recall as a critique

One of the earliest and most powerful critiques of the original Tversky and Kahneman study on the availability heuristic was the Schwarz et al. study which found that the ease of recall was a key component in determining whether a concept became available. Many studies since this criticism of the original availability heuristic model have repeated this initial criticism, that the ease of recall factor became an integral facet of the availability heuristic itself (see Research section).

Alternative explanations

Much of the criticism against the availability heuristic has claimed that making use of the content that becomes available in our mind is not based on the ease of recall as suggested by Schwarz et al. For example, it could be argued that recalling more words that begin with K than words with the third letter being K could arise from how we categorize and process words into our memory. If we categorize words by the first letter and recall them through the same process, this would show more support for the representative heuristic than the availability heuristic. Based on the possibility of explanations such as these, some researchers have claimed that the classic studies on the availability heuristic are too vague in that they fail to account for people's underlying mental processes. Indeed, a study conducted by Wanke et al. demonstrated this scenario can occur in situations used to test the availability heuristic.

A second line of study has shown that frequency estimation may not be the only strategy we use when making frequency judgments. A recent line of research has shown that our situational working memory can access long-term memories, and this memory retrieval process includes the ability to determine more accurate probabilities.

See also

References

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