The Availability Bias: How to Overcome a Common Cognitive Distortion

“The attention which we lend to an experience is proportional to its vivid or interesting character, and it is a notorious fact that what interests us most vividly at the time is, other things equal, what we remember best.” —William James

The availability heuristic explains why winning an award makes you more likely to win another award. It explains why we sometimes avoid one thing out of fear and end up doing something else that’s objectively riskier. It explains why governments spend enormous amounts of money mitigating risks we’ve already faced. It explains why the five people closest to you have a big impact on your worldview. It explains why mountains of data indicating something is harmful don’t necessarily convince everyone to avoid it. It explains why it can seem as if everything is going well when the stock market is up. And it explains why bad publicity can still be beneficial in the long run.

Here’s how the availability heuristic works, how to overcome it, and how to use it to your advantage.

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How the availability heuristic works

Before we explain the availability heuristic, let’s quickly recap the field it comes from.

Behavioral economics is a field of study bringing together knowledge from psychology and economics to reveal how real people behave in the real world. This is in contrast to the traditional economic view of human behavior, which assumed people always behave in accordance with rational, stable interests. The field largely began in the 1960s and 1970s with the work of psychologists Amos Tversky and Daniel Kahneman.

Behavioral economics posits that people often make decisions and judgments under uncertainty using imperfect heuristics, rather than by weighing up all of the relevant factors. Quick heuristics enable us to make rapid decisions without taking the time and mental energy to think through all the details.

Most of the time, they lead to satisfactory outcomes. However, they can bias us towards certain consistently irrational decisions that contradict what economics would tell us is the best choice. We usually don’t realize we’re using heuristics, and they’re hard to change even if we’re actively trying to be more rational.

One such cognitive shortcut is the availability heuristic, first studied by Tversky and Kahneman in 1973. We tend to judge the likelihood and significance of things based on how easily they come to mind. The more “available” a piece of information is to us, the more important it seems. The result is that we give greater weight to information we learned recently because a news article you read last night comes to mind easier than a science class you took years ago. It’s too much work to try to comb through every piece of information that might be in our heads.

We also give greater weight to information that is shocking or unusual. Shark attacks and plane crashes strike us more than an accidental drowning or car accidents, so we overestimate their odds.

If we’re presented with a set of similar things with one that differs from the rest, we’ll find it easier to remember. For example, of the sequence of characters “RTASDT9RTGS,” the most common character remembered would be the “9” because it stands out from the letters.

In Behavioural Law and Economics, Timur Kuran and Cass Sunstein write:

“Additional examples from recent years include mass outcries over Agent Orange, asbestos in schools, breast implants, and automobile airbags that endanger children. Their common thread is that people tended to form their risk judgments largely, if not entirely, on the basis of information produced through a social process, rather than personal experience or investigation. In each case, a public upheaval occurred as vast numbers of players reacted to each other’s actions and statements. In each, moreover, the demand for swift, extensive, and costly government action came to be considered morally necessary and socially desirable—even though, in most or all cases, the resulting regulations may well have produced little good, and perhaps even relatively more harm.”

Narratives are more memorable than disjointed facts. There’s a reason why cultures around the world teach important life lessons and values through fables, fairy tales, myths, proverbs, and stories.

Personal experience can also make information more salient. If you’ve recently been in a car accident, you may well view car accidents as more common in general than you did before. The base rates haven’t changed; you just have an unpleasant, vivid memory coming to mind whenever you get in a car. We too easily assume that our recollections are representative and true and discount events that are outside of our immediate memory. To give another example, you may be more likely to buy insurance against a natural disaster if you’ve just been impacted by one than you are before it happens.

Anything that makes something easier to remember increases its impact on us. In an early study, Tversky and Kahneman asked subjects whether a random English word is more likely to begin with “K” or have “K” as the third letter. Seeing as it’s typically easier to recall words beginning with a particular letter, people tended to assume the former was more common. The opposite is true.

In Judgment Under Uncertainty: Heuristics and Biases, Tversky and Kahneman write:

“…one may estimate probability by assessing availability, or associative distance. Lifelong experience has taught us that instances of large classes are recalled better and faster than instances of less frequent classes, that likely occurrences are easier to imagine than unlikely ones, and that associative connections are strengthened when two events frequently co-occur.

…For example, one may assess the divorce rate in a given community by recalling divorces among one’s acquaintances; one may evaluate the probability that a politician will lose an election by considering various ways in which he may lose support; and one may estimate the probability that a violent person will ‘see’ beasts of prey in a Rorschach card by assessing the strength of association between violence and beasts of prey. In all of these cases, the assessment of the frequency of a class or the probability of an event is mediated by an assessment of availability.”

They go on to write:

“That associative bonds are strengthened by repetition is perhaps the oldest law of memory known to man. The availability heuristic exploits the inverse form of this law, that is, it uses strength of association as a basis for the judgment of frequency. In this theory, availability is a mediating variable, rather than a dependent variable as is typically the case in the study of memory.”

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How the availability heuristic misleads us

“People tend to assess the relative importance of issues by the ease with which they are retrieved from memory—and this is largely determined by the extent of coverage in the media.” —Daniel Kahneman, Thinking Fast and Slow

To go back to the points made in the introduction of this post, winning an award can make you more likely to win another award because it gives you visibility, making your name come to mind more easily in connection to that kind of accolade. We sometimes avoid one thing in favor of something objectively riskier, like driving instead of taking a plane, because the dangers of the latter are more memorable. The five people closest to you can have a big impact on your worldview because you frequently encounter their attitudes and opinions, bringing them to mind when you make your own judgments. Mountains of data indicating something is harmful don’t always convince people to avoid it if those dangers aren’t salient, such as if they haven’t personally experienced them. It can seem as if things are going well when the stock market is up because it’s a simple, visible, and therefore memorable indicator. Bad publicity can be beneficial in the long run if it means something, such as a controversial book, gets mentioned often and is more likely to be recalled.

These aren’t empirical rules, but they’re logical consequences of the availability heuristic, in the absence of mitigating factors.

We are what we remember, and our memories have a significant impact on our perception of the world. What we end up remembering is influenced by factors such as the following:

  • Our foundational beliefs about the world
  • Our expectations
  • The emotions a piece of information inspires in us
  • How many times we’re exposed to a piece of information
  • The source of a piece of information

There is no real link between how memorable something is and how likely it is to happen. In fact, the opposite is often true. Unusual events stand out more and receive more attention than commonplace ones. As a result, the availability heuristic skews our perception of risks in two key ways:

We overestimate the likelihood of unlikely events. And we underestimate the likelihood of likely events.

Overestimating the risk of unlikely events leads us to stay awake at night, turning our hair grey, worrying about things that have almost no chance of happening. We can end up wasting enormous amounts of time, money, and other resources trying to mitigate things that have, on balance, a small impact. Sometimes those mitigation efforts end up backfiring, and sometimes they make us feel safer than they should.

On the flipside, we can overestimate the chance of unusually good things happening to us. Looking at everyone’s highlights on social media, we can end up expecting our own lives to also be a procession of grand achievements and joys. But most people’s lives are mundane most of the time, and the highlights we see tend to be exceptional ones, not routine ones.

Underestimating the risk of likely events leads us to fail to prepare for predictable problems and occurrences. We’re so worn out from worrying about unlikely events, we don’t have the energy to think about what’s in front of us. If you’re stressed and anxious much of the time, you’ll have a hard time paying attention to those signals when they really matter.

All of this is not to say that you shouldn’t prepare for the worst. Or that unlikely things never happen (as Littlewood’s Law states, you can expect a one-in-a-million event at least once per month.) Rather, we should be careful about only preparing for the extremes because those extremes are more memorable.

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How to overcome the availability heuristic

Knowing about a cognitive bias isn’t usually enough to overcome it. Even people like Kahneman who have studied behavioral economics for many years sometimes struggle with the same irrational patterns. But being aware of the availability heuristic is helpful for the times when you need to make an important decision and can step back to make sure it isn’t distorting your view. Here are five ways of mitigating the availability heuristic.

#1. Always consider base rates when making judgments about probability.
The base rate of something is the average prevalence of it within a particular population. For example, around 10% of the population are left-handed. If you had to guess the likelihood of a random person being left-handed, you would be correct to say 1 in 10 in the absence of other relevant information. When judging the probability of something, look at the base rate whenever possible.

#2. Focus on trends and patterns.
The mental model of regression to the mean teaches us that extreme events tend to be followed by more moderate ones. Outlier events are often the result of luck and randomness. They’re not necessarily instructive. Whenever possible, base your judgments on trends and patterns—the longer term, the better. Track record is everything, even if outlier events are more memorable.

#3. Take the time to think before making a judgment.
The whole point of heuristics is that they save the time and effort needed to parse a ton of information and make a judgment. But, as we always say, you can’t make a good decision without taking time to think. There’s no shortcut for that. If you’re making an important decision, the only way to get around the availability heuristic is to stop and go through the relevant information, rather than assuming whatever comes to mind first is correct.

#4. Keep track of information you might need to use in a judgment far off in the future.
Don’t rely on memory. In Judgment in Managerial Decision-Making, Max Bazerman and Don Moore present the example of workplace annual performance appraisals. Managers tend to base their evaluations more on the prior three months than the nine months before that. It’s much easier than remembering what happened over the course of an entire year. Managers also tend to give substantial weight to unusual one-off behavior, such as a serious mistake or notable success, without considering the overall trend. In this case, noting down observations on someone’s performance throughout the entire year would lead to a more accurate appraisal.

#5. Go back and revisit old information.
Even if you think you can recall everything important, it’s a good idea to go back and refresh your memory of relevant information before making a decision.

The availability heuristic is part of Farnam Street’s latticework of mental models.