You’ve probably heard the phrase, “You are what you eat!,” from your parents at one point or another. What they mean is that the state of your physical health will reflect the kinds of foods you’ve been eating – for example, heart disease and obesity are the results of eating too much junk food. Well, in a similar way, the state of your thoughts – meaning the types of subjects you think about and your opinions on those subjects – is greatly determined by the kinds of information that are readily available for you to consume, whether it’s news, film, music, or even gossip you overhear from friends. 


An extreme example of how the kinds of information exposed to a person can influence their beliefs is the shark terror that gripped the summer of 1975. Why did this phenomenon occur? The film Jaws had just been released, and it was an instant hit. Most of the general American public had little prior knowledge about sharks and based all their understanding of sharks on the information given by the movie. 

If you haven’t seen Jaws before, it’s about how a huge great white shark attacks beachgoers near a New England summer vacation hotspot. After watching Jaws, many people were convinced that sharks are a danger to humanity and often prey on humans (which is untrue: shark attacks on humans are extremely rare). Thus, beach attendance dropped nationwide in the summer of 1975, and the number of sharks killed by fishermen increased significantly after the movie’s release. This example demonstrates the availability heuristic perfectly: the availability heuristic occurs whenever a person’s beliefs about a certain topic are shaped by whatever information is most easily accessible to them. 

Definition of Availability Heuristic

“Heuristic” is a scientific word for mental shortcut, and when a person uses a heuristic, they’re basically making an easy-to-understand oversimplification of a given subject. Altogether, the phrase “availability heuristic” refers to when you base your opinions and/or predictions about the future upon only the most easily accessible information, such as an extremely popular movie like Jaws

The History

Tversky and Kahneman wrote one of the first breakthrough papers about the availability heuristic. This paper described a particularly significant experiment, dubbed the “K” study, that involved asking a group of subjects, “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?” A majority of the subjects answered that they thought it was more likely that a random word would start with a K. 

What’s the explanation for this result? Well, Tversky and Kahneman hypothesized that native English speakers can easily and immediately think of many words that begin with K, but would require more time and effort to think of any words that have K as the third letter. Essentially, Tversky and Kahneman’s group of subjects consulted the source of information that was most easily available to them – their own brains. Based on their personal abilities to mentally list more words that begin with K than words that have K as the third letter, subjects made the general assumption that words beginning with K are more common in the English language. However, the reality is that words with K as the third letter are three times more numerous in the English language than words beginning with K. 

This study reveals that people rely on the information that is most readily available to them in order to make judgements – a cognitive bias known as the availability heuristic.

Why Care?

In recent years, the information that is most easily accessible to many people comes from the Internet – especially social media. When most people go to sites like Facebook, they tend to start by searching subjects that they’re already interested in, and click on posts or articles that align with their personal beliefs. Afterwards, most social media sites and even news sites have algorithms that take note of what content you tend to click on, and then they continue to recommend you more of the same stuff. Because of these algorithms, the information that is most easily available to people is a limited collection of articles, ads, and videos that specifically cater to their individual point of view. When the availability heuristic comes into play, this can lead to people being extremely stuck in their own opinions and prevent them from being empathetic to others’ viewpoints.

Let’s give a specific example of how the algorithms on social media and news sites can worsen divisions among people. Here’s a character named Elena who’s a frequent reader of the New York Times website. She doesn’t have all day to read about everything that’s happening, so she always goes directly to her “Recommended for You” list. Elena considers herself a Democrat – that obviously affects the kinds of articles she initially gravitates towards. The New York Times’ algorithm picks up on Elena’s reading preferences, and shows her more articles written from a Democratic viewpoint, reporting Democratic stances in political debates, highlighting the merits of Democratic political candidates, and sometimes criticizing Republican politicians. As this goes on, Elena’s continually surrounded by Democratic opinions that likely support her own political beliefs, and the availability heuristic may cause her to believe that her views are objectively “correct,” or that the majority of the population shares her opinions. What happened to Elena in this hypothetical situation actually happens to members of any and all political parties, making it harder and harder for people of differing political opinions to have civil, open-minded conversations.

    Learn More

    1. Fox, Craig R. “The Availability Heuristic in the Classroom: How Soliciting More Criticism Can Boost Your Course Ratings.” Judgment and Decision Making, vol. 1, no. 1, 2006, p. 6.
    2. Kliger, Doron, and Andrey Kudryavtsev. “The Availability Heuristic and Investors’ Reaction to Company-Specific Events.” Journal of Behavioral Finance, vol. 11, no. 1, Mar. 2010, pp. 50–65. Taylor and Francis+NEJM, doi:10.1080/15427561003591116.
    3. Schwarz, Norbert, et al. “Ease of Retrieval as Information: Another Look at the Availability Heuristic.” Journal of Personality and Social Psychology, vol. 61, no. 2, 1991, pp. 195–202. APA PsycNET, doi:10.1037/0022-3514.61.2.195.
    4. Tversky, Amos, and Daniel Kahneman. “Availability: A Heuristic for Judging Frequency and Probability.” Cognitive Psychology, vol. 5, no. 2, Sept. 1973, pp. 207–32. ScienceDirect, doi:10.1016/0010-0285(73)90033-9.

    Think Further

    1. Other than the Internet, can you list 3 other sources of information that are readily accessible to people?
    2. What are some advantages to using the availability heuristic?
    3. What are some possible negative consequences to using the availability heuristic?

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