Thinking About Design, Fast and Slow Theory

Thinking About Design, Fast and Slow

The premise of Daniel Kahneman’s book Thinking, Fast and Slow is that we employ two very different ways of thinking. The book is very dense, and a highly recommended read. Kahneman says that the main goal of his book is to arm people with a better vocabulary about thinking, which in turn allows them to understand our biases, decisions and behavior better. While that is great for everyone, I think it’s especially valuable for designers. It lets you see that most of the time, there is no ‘one’ user, but one with multiple modes of thinking. Most good designers have observed their users interacting with their products multiple times. Insights from this book let you put more weight on these observations.

Kahneman refers to the fast and slow modes of thinking ‘systems’. System 1 is fast, automatic, intuitive, and associative. It can’t be switched off—just try not to think about pink polar bears while reading this sentence, and you will understand. System 2 is slow, effortful and thorough. In contrast to System 1, it needs to be switched on deliberately. Thinking slow is more difficult and costs energy. You can try some mental arithmetic to experience it in action—try solving 17 x 24.

Make me think fast

The most popular book on usability is Steve Krug’s Don’t make me think. In the spirit of Kahneman, I think that what he really means is don’t make me think slow. When we try to determine if something is designed well, we almost only use System 1. A good design needs to react in the right way if we only use our intuition to make choices. We associate quickly and find it easy to think in metaphors. We want designers to take advantage of those skills, so we can understand an interface from the first time we use it.

We mostly use System 1 for interacting with the tools we use everyday, like our email client and text editor. Ideally, System 2 only comes to play when you are actually working with the content or subject of the tool, like an email or written story. This is why I believe that a good designer understands and uses emotion when designing interfaces and tools. The fast mode of thinking is highly sensitive to cues from our environment and other people. We use it to react to signs of danger, and to read body language. It often affects our emotions subconsciously: someone or something can just give us a good or bad feeling, while we don’t feel the need to explain why. Something you use everyday needs to do a good job at communicating with you on the level of System 1.

The limits of fast thinking

Because using System 2 is hard and easily tires us out, we usually accept what System 1 tells us to do. This is not always a good thing, because the speed of System 1 comes at a cost. It oversimplifies things, does not think ahead much, it gossips and reaches shortsighted conclusions. It is the reason human beings have so many cognitive biases and are terribly bad at understanding statistics.

The list of cognitive biases is enormous, and some of them can have a great impact on how people perceive your design. A good example is the fundamental attribution error, which describes the tendency of people to explain the behavior of others by their personality, while explaining their own behavior with situational factors. When a user pushes the wrong button while using an interface, the way the button is placed or styled gets blamed. But when the user didn’t make a mistake and gets an error, a lot of the time it gets personal: it must be that the makers of the tool that are incompetent, don’t care, or maybe be even actively out to hurt them.

Kahneman uses an example where he describes how a chief investment officer decided to invest 10 million dollars in the stock of Ford. Instead of researching if the stock was underpriced, he explained he recently attended an automobile show and had been impressed by their car-making skills, and decided to buy the stock shortly thereafter. This is the affect heuristic in play: his judgement was directly guided by feelings of liking or disliking. System 1 guided him in a million dollar decision, without considering extra information.

Keep this in mind while making your interface

I only scratched the surface of this amazing book, but I think these are the most important takeaways for designers:

  • Understand that your users are mostly employing System 1 while using your product. Keep that in mind while trying to get into your users heads. Your System 2 likes to overthink your design decisions: be aware of that, and try to rely on your gut.

  • System 1 predictably makes cognitive mistakes. You can adjust your design to help users avoid these mistakes, or use the biases to let them feel good about you.

  • Beware of your own biases while designing. Kahneman argues that this is much easier to see in others than in yourself. That’s why designing in pairs can be a huge benefit.

I hope you will like the book as much as I did!

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