The Availability Heuristic and Public Policy Priorities

Or, Why Terrorist Benefits Cheats Aren’t Taking Your Jobs.

“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?”

In 1973, this question was posed to 150 people, and over two thirds responded that the word is more likely to begin with K. In fact, the English language has about three times as many words with K in the third position than in the first. Similar results were found for the letters L, N, R and V – which all appear far more frequently in the third position, yet were deemed far more likely to be starting letters.

In explaining these results, Nobel Prize winning psychologists Amos Tversky and Daniel Kahnemann (1973) coined the term availability heuristicThey discovered that when faced with the first-or-third letter problem, people estimated the frequency of each group by seeing how easily examples of each could be recalled. It is easy to think of words beginning with K, L, N, and R; less so to think of words with these letters in third position. Accordingly, K, L, N and R were deemed to be more frequent as first letters, and less so as third.

This phenomenon was found to extend far beyond the letter game: We all fall back on availability heuristic when we assess how frequent or likely something is by the ease with which examples come to mind.

In assessing risks, for example, the heuristic prompts us to substitute the question, “how dangerous is this?” for “how easily can I recall examples of this being dangerous?” This distinction may not have been critical for our ancestors – common dangers (predators) would naturally have been easier to recall than uncommon ones (meteors), and would also pose the most serious threat to survival. The onset of mass media, however, has destroyed all equivalence between ‘recallability’ and danger.

So what it is that now makes some threats more recallable than others? Several factors seem to be at work, most notably the level of emotion the risk elicits, its familiarity, and its salience.

Where strong emotions are involved, people tend to focus on the badness of the outcome, rather than on the probability that the outcome will occur. The resulting “probability neglect” helps to explain excessive reactions to low-probability risks of catastrophe (Sunstein, 2003). A risk that is familiar, like that associated with terrorism, will be seen as more serious than a risk that is less familiar, like that associated with sun-bathing. Salience is also important: “The impact of seeing a house burning on the subjective probability of such accidents is probably greater than the impact of reading about a fire in the local paper” (Tversky and Kahneman, 1982).

Lets now examine these availability factors in relation to the UK media and public policy priorities, in particular the highly-covered topics of terrorism, immigration, and benefit fraud.

Terrorism is a statistically tiny risk to public safety, yet looms alarmingly large in the public eye. M15 instructs UK citizens to “always remain alert to the danger of terrorism”, yet since 2001 fewer British citizens have been killed by terrorism than by bee stings. It is clear, of course, why the risk has been socially amplified beyond proportion; the threat of random, violent attacks is could scarcely be more emotionally charged, familiar, and salient.

The threat posed by excessive immigration is  clearly less violent, but  no less emotional in its (much exploited) suggestions of injustice and  insecurity- and is certainly made familiar by overrepresentation in the news.

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Accordingly, the British public overestimate the scale of immigration; believing on average that immigrants make up 24.4% of the population (the real figure is c.13%).

For similar reasons, we also overestimate the amount of public money that goes towards fraudulent state benefit claims, and believe that £24 out of every £100 is claimed fraudulently, when the true figure is 70p (34 times less than the estimate).

Importantly, the result of being mistaken about these numbers is not simply the loss of having true beliefs about the world, or the trouble of worrying about things that are not half as bad as you thought. Placing undue emphasis on the availability of a risk also allows for hugely disproportionate, and often questionably legal, law making. Lets continue with the examples of terrorism, immigration, and state benefits.

Over the last 15 years, the UK has seen six terrorism related Acts, which have variously allowed the state to indefinitely detain foreign nationals without charge, to commit pre-charge detention in terrorism cases, and to stop and search citizens without suspicion.

Since 2012, the Immigration Rules have required applicants or their partners to have an annual income of at least £18,600 (the National Minimum Wage, incidentally, is approximately c. £13,500) in possible violation of Article 8 of the European Convention on Human Rights.

Since 2013, people living in social housing with one or two spare bedrooms had their benefit payments reduced by 14% or 25% respectively, even when a disability has meant they could not relocate. Given the number of disabled people facing unemployment, 64% of claimants found themselves in this situation; the case is to be held before the Supreme Court.

These examples are illustrative only, and there are undeniably situations that merit a restriction on human rights, a limit on immigration, or restraints on welfare payments. But it is valuable to acknowledge that in a cataclysm of public concern, legislators will be far more able to push through questionable legislation by exploiting a fear that is not rooted in numbers or probabilities, but rather emotion, familiarity, and salience.

The the availability heuristic can also prevent the rational and cost-effective pursuit of goals we care about. Perhaps people support counter-terrorism efforts, for example, out of a concern for the right to life, or for the promotion of peace, or for fear of losing fundamental rights and freedoms in the West. If so, a better approach may consider preventing heart disease or cancer, supporting organisations that encourage inter-state cooperation, or backing social change organisations that seek to entrench human rights.

The availability heuristic is arguably so pervasive to public policy that is does not warrant mentioning: As the argument goes, the public should get what it wants, and something must be seen to be done in response to perceived threats. But if we care about making decisions that will affect the state of the world, then it heuristic is devastating in its distortion of priorities. One response might be to read less news, and think more thoughts; as Rolf Dobelli writes, “News is to the mind what sugar is to the body”.


Briñol, P., Petty, R. E., & Tormala, Z. L. (2006). The malleable meaning of subjective ease. Psychological Science, 17(3), 200-206.

Sunstein, C. R. (2003). Terrorism and probability neglect. Journal of Risk and Uncertainty, 26(2-3), 121-136.

Tversky, A., & Kahneman, D. (1973). Availability: A heuristic for judging frequency and probability. Cognitive psychology, 5(2), 207-232.

1 Comment

  1. Fascinating. Love the prose style. Understated and persuasive. And on such charged issues. Well done.

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