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  • Bitesize Behaviour Host

Series 1, Episode 5: Heuristics

Now before we go on, let’s do a really quick recap of everything we’ve discussed so far.

From an evolutionary point of view, we haven’t evolved to deal with complexity very well. On top of this, the amount of information we can store and process in our heads at any one time is really, really limited. To deal with decision making, we’ve evolved two systems. System one which is quick and intuitive, and system two which is slow and takes a great deal of effort to use. Now, when we try to make decisions that are complicated, we have evolved a neat trick that allows us to take a shortcut in order to reach decision, and this is what we will focus on in this episode. Today, we discuss heuristics.

Now, please don’t be put off by the scientific sounding word. What it means and how it works, is much easier to understand.


Everyday we make decisions and in some cases, yes, we can give these slow, deliberate thought; really think about stuff. But most of the time, we need to make a quick decision - and this is where heuristics come in to play. They are simply rules-of-thumb we’ve developed, mental tools to help us make quick decisions.

Now, it’s important to note that heuristics, these rules-of thumb aren’t about making the perfect decision, they are about making a quick decision with as little effort as possible. There are several heuristics that we use but today we will discuss three examples that everyone reading will recognise and it will make everything we’ve discussed so far in the previous episodes all start to make perfect sense. At least I hope it will.

The following heuristics (rules-of-thumb) all have self explanatory names, names that tell us exactly what they are about, and the first one is about the “availability of information”.


The availability heuristic is one of the most powerful shortcuts we use in decision making. In essence, when we need to make a decision we have to first get past the first thing that comes to our mind.

If I said to you all, do you think flying is safe, you’ll find it hard to not think first of the odd plane crash instead of the millions of safely landed plane journeys. That’s because we have a natural tendency to focus on vivid or negative messages, or use something we’re recently seen or experienced to dominate our thoughts.

So as another example, we may make a decision that a place, a holiday destination, is unsafe to visit simply because the news is talking about it a lot in a negative way - and we can see on the news what they mean because they are showing us vidid, negative, images. What we see, which is often what they want us to see, distorts our fact-based reality, and we remember this for a long, long time. I know people who still won’t go on holiday to Bosnia, Croatia, or Serbia because of a brutal war that ended 25 year ago.


The second heuristic - called the representativeness heuristic - is the one we use to decide whether a person, an event, or a thing should be put into a certain category (safe, dangerous, friendly, nasty) by comparing it to how similar it is to what we believe is typical.

What I mean by this is, for example, a chair may have four legs, a seating part, and some sort of back support. If we see something that looks like a chair, then we will automatically, without even thinking about it, place it in the category of ‘chair’.

Unfortunately we do this with people all the time. We look at certain characteristics of a person and put them, almost without question, into a category. Nice, friendly, unfriendly, smart, stupid - before we even get to really know the person. Remember we were taught to never judge a book by its cover, but I suspect we go through life judging lots of books by their cover.


The final heuristic is all really powerful and links back to everything we’ve discussed in this and the previous episodes. The affect heuristic is a mental shortcut we use to make a decision but one that is heavily influenced by our current emotion - fear, pleasure, surprise, and so on.

Like the other two heuristics we’ve talked about, this is a shortcut that reduces the decision-making process and allows people to function without having to complete an extensive search for information. The affect heuristic is often used when we need to make a decision involving risk versus reward - or exploring the benefits of something, depending on the positive or negative feelings that we associate with it.

In other words, the affect heuristic is pretty much “going with your gut”. If our feelings towards something are positive, then we are more likely to judge the risks as low and the benefits high. On the other hand, if we’re feeling negative towards something, we are more likely to perceive the risks as high and benefits low.

So, those are the three main heuristics, rules of thumb, that we unconsciously use when we are making decisions. Now, if by using these rules-of-thumb we still don’t reach a satisfactory decision, and we need to dig a little deeper, or become more specific, this is when we will apply our own filters to the information we need to use to reach a decision as quickly as we can, and these filters, are in essence, our behaviour biases.


A quick online search for “behavioural biases” will reveal there are hundreds to learn about. There are so many! And that’s why we will dedicate the entire next series to exploring 18 specific behavioural biases, all of which have a strong influence how we make decisions, all of which impact how we navigate the world around us, and all of which have their own unique role to play in our overall wellbeing.

That’s it for this kind of foundational Series One. I hope that’s given you an insight into what is going on in your head when you’re making decisions, although the picture will become much clearer as we go through series two!