Availability Heuristics and Survivorship Bias: confusing visible for important

Why do flights seem scarier after the news of a plane crash?
Why do we get more cautious after we hear that a friend
…and why does starting a business seem easy?

Our brains tend to favour information that is easy to remember or carries a greater emotional weight.
This bias is called Availability Heuristics and is a common brain shortcut.
It may be effective at saving brainpower now, but it can turn into a costly irrational mistake.

Let’s explore it together.

Everyday Availability Bias

Look around you. What do you see?
Chances are, the scene around you is full of details.
People, conversations, colours, textures, movements, objects, smells, pathways, temperature, air pressure, noises, lighting…even if you’re staring at a blank wall, the richness of information is potentially overwhelming. And that’s just the room you’re in. Now.

Filtering and simplifying information prevents us from thought paralysis (and it’s also how the brain can work on “only” 300 calories a day).

Heuristics is just a fancy word for the simple rules the brain uses to constantly assess the situation around us. Availability Heuristics is one of the most common tools our brains use to evaluate our environment, quickly.

Essentially, information that is readily available carries more weight when evaluating the probability of something happening. Here’s what skews our judgement:

  • Ability to recall. How easy it easy to remember something.
  • Frequency and repetition. How much and how often we are exposed to something.
  • Emotional weight. The more graphic and emotionally intense an event or piece of information is, the more it will be given priority over the rest.

This built-in brain bias is a useful shortcut to make fast evaluations with limited information. However, because we tend to be unaware of it happening in the background we trust our perception blindly, turning a shortcut into a brainaccuracy *.

This has dangerous implications: whatever we are exposed to on a regular and intense basis, literally determines our perception and experience of reality.
This puts a lot of power over the quality of your life in the hands of the media and your peer group.

Your peer group (the group of people around you you actually listen to) determines your perception and sets your personal standards at a chemical level. They also decide which topics and point of views your conversations are going to focus on, shaping your reality through Availability Heuristics.

availability heuristics 2

The media, also has great influence over what information and viewpoints you’re exposed, deciding how often and at which intensity (often cranked up to capture your attention).
Like we will see in the next few examples, over time this shapes your perception of the world.
Whatever the media decides to focus on becomes the public’s concerns and priority, which in turn dictate governments’ agendas. Large scale brainaccuracies become reality.

availability heuristics 1

Examples and Studies

Crime rate: perception vs reality

Just before the last US election, 57% of voters said that crime had got worse since 2008.
When we zoom in on Trump voters specifically, that figure was 78%.
However, official government statistics paint a very different picture of reality, with violent crime falling by 19% and property crime falling by 23% between 2008 and 2015 (the most recent data yet available).

availability heuristics crime-rate

However, media coverage does not report the actual level of crime, but what’s “worth reporting on”.
2015 saw a minor blip in the overall downward trend (one of many), extensively documented episodes of violence happening in key cities like Chicago, and the Trump campaign repeating that crime is at a 45 year high triggered our good friend…Availability Heuristics.

Availability Heuristics

Personal safety and life decisions

Here’s a personal example.
On May 22nd, a terrorist attack happened in Manchester, not too far from where I live.
The next day, I had two conversations with people saying “I am considering moving abroad now”. Availability was skewing their perception of safety.
As distressing as that day was, you’re still twice as likely to die in an elevator than in a terrorist attack. When it comes to heart disease caused by poor diet and lifestyle, the odds of dying are over 100,000 times.
In fact, terror-related deaths in the UK in the past 17 years are at a record low: 36 times less than those between 1970 and 2000. A similar trend can be seen across the rest of Europe.

Gender balance

In a study, participants were read a list of personalities from both sexes.
Of the four possible lists, each included 39 names, read at a pace of one name every 2 sec.
Two of the lists included 19 names of famous women and 20 names of less famous men.
The two other lists consisted of 19 names of famous men and 20 names of less famous women.

The result?
More than 80% of participants erroneously judged the class consisting of the more famous names to be more frequent. Ability to recall and emotional weight skewed reality once again.

Everyday examples

More examples of Availability bias are: believing that divorces rates are going up after a few friends divorced; believing that shark attacks are deadlier than falling aeroplane parts; selling all stocks after a market crash; being worried about losing one’s job after seeing headlines of businesses closing down.
I’m sure you can add many more from your own experience.

Survivorship bias

Availability Heuristics gives birth to another dangerous brainaccuracy: Survivorship Bias.
This is the shortcuts to notice people or things that made it past a certain selection process, and ignore those that did not.

The classic example is business success.
Since successful companies get far greater exposure than those that do not succeed, information about successes is much more available and richer in detail. As a consequence, the perception of the difficulty of starting a business is heavily skewed, and often ignores and hides the very weak points that make most companies fold.

The same happens with famous entrepreneurs and personalities: from “Train like Andy Murray” to “Drop out of school like Steve Jobs”, survivorship bias ignores those that follows the same path but had opposite outcomes. It also assumes that these people succeeded because of a particular, decontextualised choice rather than in spite of it.


One of my favourite examples comes from the military.
During World War II, the Navy examined where US bombers were hit most often, in order to determine where to reinforce aircrafts and reduce losses. Initially, the initiative had little success.
Until the Navy realised that they were only assessing bombers that returned safely, ignoring those that were fatally hit.
The programme started to disregard the areas that were heavily hit, since the carriers were able to take damage in those points and still make it home, and started reinforcing the points that remained unscathed on surviving planes.

Through Availability Heuristics, Survivorship Bias makes it easy to misestimate the likelihood of something succeeding, and may actually hide the steps necessary for it to happen.

Now you know

Although the true probability of something happening is unknowable (especially in real time), being aware of what goes on in the background will help you balance Availability Heuristics and make better decisions every day.

In the next post, we are going to talk about why shortcuts and brainaccuracies are a thing in the first place.

— Matt

Now check out what’s the worst time of the day to make a good decision.

*Yes, I made the word ‘Brainaccuracy’ up (and now it’s miiine).