The Availability Heuristic: How Recall Ability Affects Perception


Anyone that had access to social media probably remembers the Ebola panic: when, in fall 2014, Ebola was everywhere– from TV and radio to all across the internet– triggered by cases of Ebola being found in the United States.

Compared to an individual being in, for example, sub-Saharan Africa, an individual in America was much more unlikely to contract (let alone die from) the disease.  However, a Gallup poll conducted in October 2014 showed that 1 in every 6 people in the U.S. were worried about contracting the Ebola virus, and a Washington Post-ABS Poll showed that 65% of Americans surveyed feared a widespread Ebola epidemic, with 31% saying that it was very concerning.

However, just 10 cases of Ebola have been documented in the U.S., compared to more than 20,000 in Africa.

So what can explain the inaccurate and heavily skewed judgments in our minds for the probability of certain events?


The Availability Heuristic (from Greek “Εὑρίσκω”, “find” or “discover”): an experience-based mental technique for problem solving, learning, and discovery that finds a a solution quickly through mental shortcuts to ease cognitive loads, using immediate examples that come to an individual’s mind to evaluate and analyze a topic, concept, method, or decision.

Basically, the brain works to find a satisfactory solution, rather than an accurate, logical one, in order to deliver a solution to a problem quickly while reducing strain on itself.  In this case, the “danger” of Ebola was emphasized and much more dominant in the news feed, and hence in the mind, it was the first example that was recalled when thinking of threats to health or mortality.

However, when compared to deaths related to smoking and alcohol, the dangers of Ebola shy in comparison: 800,000 U.S. deaths per year vs. 1, respectively.

“There are situations in which people assess the frequency of a class or the probability of an event by the ease with which instances or occurrences can be brought to mind. For example, one may assess the risk of heart attack among middle-aged people by recalling such occurrences among one’s acquaintances. Similarly, one may evaluate the probability that a given business venture will fail by imagining various difficulties it could encounter. This judgmental heuristic is called availability. Availability ia a useful clue for assessing frequency or probability, because instances of large classes are usually reached better and faster than instances of less frequent classes. However, availability is affected by factors other than frequency and probability. Consequently, the reliance on availability leads predictable biases,[…]” – Tversky and Kahneman (1974)

The Availability Heuristic is a powerful cognitive distortion that shows the dangers of “out of sight, out of mind”: the believability of something is attributed to the ease of recall; if the brain cannot remember it, then it must not be true.

It operates on the assumption that if something can be recalled, it must be important or more important than alternative solutions which are not as readily recalled.  A decision maker relies upon knowledge that is readily available rather than examine other alternatives or procedures; as a result, individuals tend to heavily weigh their judgments toward more recent information, making new opinions biased toward that latest news.

In other words, the easier it is to recall the consequences of something, the greater those consequences are often perceived to be.

This is inaccurate because our recall of facts and events is distorted by the vividness of information, the number of repetitions we are exposed to through advertisements on radio and television, and their subsequent familiarity.


Here are some more examples: a survey conducted in 2010 in the U.S. examined the most feared ways to die.  Six of the top ten results were: terrorist attacks, shark attacks, airplane crashes, murders, natural disasters, and falling.  What do these six results have in common?  Although they are the most “feared”, they are also some of the most unlikely causes of death in the United States.

  1. Terrorist attack: Your chances of dying from such an attack are 1 in 9.3 million, which is slightly greater than your risk of dying in an avalanche.  Front page news of terrorist incidents worldwide exacerbate the availability heuristic-
  2. Shark attacks: Even if you live near the ocean, your chances of being attacked by a shark are 1 in 11.5 million. In the last 500 years, only 1,909 confirmed shark attacks occurred worldwide; of the 737 that happened in the United States, only 38 people died. The chances of being killed by a shark are much slimmer than that of a shark attack: 0 in 264.1 million.
  3. Airplane crashes: Your chances of being involved in a fatal airline accident are once every 19,000 years.
  4. Being murdered: “Worldwide, one person is murdered every 60 seconds!” “Every year, ___ people are murdered.”  However, in the year 2000, about 520,000 people were murdered, compared with 6 million who died of cancer that same year.
  5. Natural disaster: The chances of dying in a natural disaster (ex. hurricane, tornado, flood, etc.), is 1 in 3,357.
  6. Falling: In 2001, 12,000 people aged 65+ died from a fall.  However, only 80 people die from falling from a tall height annually.

The actual annual leading causes of death in the U.S., the ones that should be feared, are:

  1. Tobacco usage: 435,000 deaths, 18.1% of total U.S. deaths
  2. Poor diet/physical inactivity: 400,000 deaths, 16.6%
  3. Alcohol consumption: 85,000 deaths, 3.5%
  4. Microbial agents: 75,000
  5. Toxic agents: 55,000
  6. Motor vehicle crashes: 43,000
  7. Incidents involving firearms: 29,000
  8. Sexual behaviors: 20,000
  9. Illicit use of drugs: 17,000

Statistically speaking, you will not die in an airplane crash, be eaten by a shark, or fall to your death.  Yet we are all much more scared of these unlikely events than we are of diabetes, heart disease, or traffic accidents.

When we’re asked to think of how likely something is, we ignore the statistical probabilities, but ask ourselves a much simpler question: “How easily can I think of an example?”; this is how the frequency and probability of events become skewed in our minds: overestimation of subjective probabilities causing overreaction.  Dramatic deaths are more memorable and more exposed by the news, so examples from all different countries are constantly shown– intensifying the effects of this heuristic.

Availability provides a mechanism by which occurrences of extreme utility (or disutility) may appear more likely than they actually are… so be aware of this– remember, we live in what we perceive.

Have you ever experienced the availability heuristic in action? Leave your comments and thoughts below!

CARROLL, J.S., 1978. … an event on expectations for the event: An interpretation in terms of the availability heuristic. Journal of Experimental Social Psychology.

CHAPMAN, L.J., 1967. “Illusory correlation in observational report”. Journal of Verbal Learning 6: 151–155.

FOLKES, V.S., 1988. The Availability Heuristic and Perceived Risk. Journal of Consumer Research.

GABRIELCIK, A. and R.H. FAZIO, 1984. Priming and frequency estimation: A strict test of the availability heuristic. Personality and Social Psychology Bulletin.

SHEDLER, J. and M. MANIS, 1986. Can the availability heuristic explain vividness effects. Journal of Personality and Social Psychology.

SCHWARZ, N., et al., 1991. Ease of retrieval as information: Another look at the availability heuristic. Journal of Personality and Social Psychology.

SCHWARZ, N. and L.A. VAUGHN, 2002. The availability heuristic revisited: Ease of recall and content of recall as distinct sources of …. Heuristics and biases: The psychology of intuitive judgment.

TVERSKY, A. and D. KAHNEMAN, 1973. Availability: A heuristic for judging frequency and probability. Cognitive Psychology.

WAENKE, M., N. SCHWARZ and H. BLESS, 1995. The availability heuristic revisited: Experienced ease of retrieval in mundane frequency estimates. Acta Psychologica.

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