Availability Heuristic Explained: How Heuristics Affect Decisions

The availability heuristic, also known as the availability bias, refers to the tendency of giving excessive importance to events more readily recalled. A heuristic is a mental shortcut people use to make decisions. This rule of thumb can ease decisions or create a bias that impacts decision-making. Rather than a full assessment of likely outcomes, people often believe that the information that comes quickest to mind is the most relevant.

The availability heuristic was first described by behavioral psychologists Amos Tversky and Daniel Kahneman in the 1970s. A series of their papers on human cognitive biases and behavioral economics, including "Judgment under Uncertainty: Heuristics and Biases” in 1974, discusses how incomplete access to information—plus the pressing needs of everyday decision-making—leads to shortcuts, many of which can lead to erroneous or less-than-ideal behavior.

The availability heuristic, like the representativeness heuristic and other causes of everyday cognitive biases, has a few different reasons:

• Efficiency: Most people don’t have time to look up the statistical probabilities of different outcomes. Human behavior means making decisions all the time, and mental shortcuts are necessary parts of cognition. While this can help people navigate the world, it can also lead to errors in judgment, especially with quick decisions.
• Ease of recall: If an event is especially easy to recall—also known as ease of retrieval—it is likely to have an outsized effect on the decision-making process, even if its real-world likelihood is relatively small. This can be because it has special significance for a person, or is especially vivid, either positively or negatively.
• Recency: If something has happened recently, it will likely be easily remembered, which can greatly affect the decision-making process of the person doing the remembering.

Like many cognitive biases, the availability heuristic is common. In some cases, being aware of the availability heuristic concept can help correct errors, especially when making an important decision. Some examples of scenarios that can create a bias for decision-makers:

1. 1. Causes of death: Certain deadly events can lodge into people’s consciousness, leading them to overestimate their prevalence. For example, people often overestimate the frequency of shark attacks, plane crashes, and other disasters, often due to media coverage of these rare events. In particular, if people have heard about one of these events recently, they will tend to greatly overestimate its likelihood of happening, especially compared to much more common fatal incidents, such as car accidents or heart attacks.
2. 2. Climate change: Climate models have had remarkable success predicting increasing extreme weather events due to climate change. However, it can be easy—especially during a period of weather that is either unusually mild for the time of year or especially cold—to discount the overall data in favor of immediate experience.
3. 3. Language: One classic example of the availability heuristic involves asking a group of people whether they think a given text is likely to have more words starting with the letter “k” than words where “k” is the third letter. Because thinking of words that start with “k” is easier than thinking of words where “k” is the third letter, respondents are likely to conclude that words starting with “k” are more common, which is not statistically accurate.

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