Top of mind

Which is the greater risk to life when you’re swimming in the ocean: shark attack or drowning? While news reports, viral videos, and films like Jaws might lead you to believe sharks are the biggest threat to an afternoon at the beach, you’re much more likely to die by drowning, even though it attracts a lot less attention. 

Why does your brain get it so wrong? This is “availability bias” at work – a mental shortcut that judges the probability of events by how quickly and easily examples come to mind. It helps you make decisions quickly, but they’re not always well-informed. 

Luckily, it’s possible to beat the bias and make better as well as more balanced choices. 

Recall, not fact

Availability bias is everywhere. It’s why we buy a lottery ticket after reading stories about multi-millionaire winners. It’s a huge contributor to fear of plane crashes. It’s why people are more likely to purchase insurance after a natural disaster. 

Medical professionals aren’t immune – one study found doctors who diagnosed two cases of a serious disease were likely to diagnose it again in the next patient even if that patient presented with a milder illness. And there’s evidence that investors make judgments about stocks they’ve heard about in the news, only to find they underperform in later years. 

At work, availability bias – a term first coined by psychologists Amos Tversky and Daniel Kahneman in a landmark 1973 paper – gets in the way of everything from rating suppliers you’ve used recently as superior to those you use infrequently, to fretting you’ll be made redundant because of news reports about people losing their jobs. 

It’s also why performance reviews are often based around one noteworthy project – that went well or, perhaps, not. 

The common thread is this: we often make decisions or cultivate opinions based on recall rather than fact, so we develop distorted perceptions of the likelihood of a shark attack, lottery win or job loss. If you can quickly think of examples of something happening, you’ll believe it’s more common. 

“Any time you’re trying to judge the probability of something happening, like getting run over by a car if you cross the road, or getting attacked by terrorists if you go to one place versus another, you’re relying on some form of availability bias,” says Ben Newell, a professor of cognitive psychology at the University of New South Wales. 

“If you don’t immediately go to Google and look up a statistic, then you’re relying on some sort of impression that you form from your memory.”

Behind the bias

What causes availability bias? 

   It’s actually pretty simple: efficiency. Making decisions – which we do 35,000 times every day – is hard work, and we often lack the time or resources to investigate all of the options relating to our choice. So the brain follows a basic principle along the lines of, ‘If I can remember it easily, it must be important’. 

“The task [of decision making] is very expensive to execute accurately, so our brain has developed a shortcut that is less accurate but works well enough that the decrease in accuracy is more than made up for by the cognitive savings in getting to an answer,” says Dr Brooke Struck, Research Director at The Decision Lab, a Canadian think-tank specialising in behavioural science. 

The trouble is that if we rely on faulty estimates of the probability of an event, our perceptions of risk and error may be skewed and lead us to make poor choices – like not swimming in the ocean for fear of a shark attack or buying a lottery ticket believing we have a realistic chance of winning next week’s jackpot. 

Beat the bias

Resisting the pull of availability bias means examining the evidence before making a decision, rather than relying on your memory. 

“What you can do is think, ‘What is the basis for this decision? Am I doing that just because I saw something on the news about it this morning or someone mentioned something about it?” says Professor Newell. 

“It’s really about stopping and thinking, ‘Okay, well if I think this, what’s the evidence that I’m basing it on?’ Your ability to step back and think about the sample of evidence that’s in front of you, or how you might be searching through your memory to find the answer, is one way of overcoming this tendency to just go with the first thing that pops into your mind.”

Checking the statistics on how many sharks attack people each year, the proportion of people who win the lottery each week, and how often planes crash before deciding whether to swim, gamble or fly is a great start. 

At work, Dr Struck says it’s helpful to rely on reports, data and other quantitative measures when it comes to measuring things like the performance of employees and external suppliers to keep availability bias in check. 

“At The Decision Lab, we track the time we spend on our client projects, our publication and various internal functions,” she says. “When it comes time to conducting performance evaluations, that time-tracking data is really useful. 

“For example, an employee stands out in my mind so clearly because of her exceptional performance on a certain project. 

“But when I look at the time-tracking data I get brought back to earth: that project was only 10 per cent of what she did last year. 

“So if I followed my intuition, which is heavily influenced by availability bias, I would neglect to pay attention to 90 per cent of the work that she does.”