Dual Process Theory

By Ben Ambridge


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Let me start by giving you a puzzle:

A notebook and pencil cost £1.10 in total. The notebook costs £1 more than the pencil. How much does the pencil cost?

10p right? Wrong. It’s 5p. The notebook costs £1 more than the pencil – which is £1.05 – so together they add up to £1.10.

This is a classic, and by now actually quite famous, puzzle that is a good example of something called dual-process theory: the idea that the brain has two different systems, two different ways of thinking or operating. This is actually a very old idea – it goes back at least as far a Harvard University psychologist called William James, who died in 1910.

In the last few years, dual process theory has gone mainstream with two very successful books – Daniel Kahneman’s Thinking, Fast and Slow, and a book by Steve Peters called The Chimp Paradox. In fact, brain scanning studies have actually found some evidence for the idea of two different systems, in two different parts of the brain.

So, what are these two systems? Daniel Kahneman gives them the not-very-exciting names of System 1 and System 2. System 1 (which is like what Steve Peters calls the Chimp brain) is evolutionary old. It’s very fast, automatic, and even unconscious but it doesn’t work logically. It works on emotions, associations, hunches, intuitions.

So if you said 10p earlier, that was your System 1 – notice how it just spat out that answer – you didn’t have to think about it. You just had a hunch that it just had to be 10p (unfortunately this was a bit of a trick question, so it turned out to be wrong).

System 2 (which is like what Steve Peters calls the computer) is much more recent in evolutionary terms. It does slow, logical, conscious reasoning – calculating. If you did manage to get the right answer – 5p – earlier, it won’t have just come to you. You’ll have engaged your System 2 and logically talked through the answer to yourself, so it will have been hard work.

What does all this mean for eCommerce? When they’re designing their site, most people are thinking only about the rational System 2. If you offer a better product, and or a lower price, people will buy from you – right?

Wrong! Because System 2 is slow and effortful, people generally are actually very bad at coolly weighing up the pros and cons before making a purchase. You need to engage their emotional, automatic System 1 too.

In fact, some of the buying decisions that might seem to call for the most rational logic – for example buying a very expensive item such as a new car – are just those ones that, in practice, are often most affected by the emotional System 1.

So, no matter what your site is selling, the way to do it most effectively is to make sure you’re always appealing to your customers’ emotional System 1 side, since it’s involved in EVERY decision that we make.

Ben Ambridge
Hi, I’m Ben. I’m a Reader in Psychology at the University of Liverpool and I lead consumer psychology at Endless Gain. I’m interested in how research findings from academic psychology can be applied in our everyday lives as consumers. And, importantly how psychology plays an influential role in ecommerce. I write a weekly psychology column for The Observer, and my book Psy-Q: You Know Your IQ - Now Test Your Psychological Intelligence has been translated into 15 languages. Check out my TED talk, "Ten Myths about Psychology, Debunked".

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