Thinking, Fast and Slow summary

To see how the two systems work, try solving this famous bat-and-ball problem:

A bat and ball cost $1.10. The bat costs one dollar more than the ball. How much does the ball cost?

What do you think when you see the word fragment “SO_P”? Probably nothing. What if you first consider the word “EAT”? Now, when you look again at the word “SO_P,” you would probably complete it as “SOUP.” This process is known as priming.

We’re primed when exposure to a word, concept or event causes us to summon related words and concepts. If you had seen the word “SHOWER” instead of “EAT” above, you probably would’ve completed the letters as “SOAP.”

Imagine you meet someone named Ben at a party, and you find him easy to talk to. Later, someone asks if you know anybody who might want to contribute to their charity. You think of Ben, even though the only thing you know about him is that he is easy to talk to.

In other words, you liked one aspect of Ben’s character, and so you assumed you would like everything else about him. We often approve or disapprove of a person even when we know little about them.

Often we find ourselves in situations where we need to make a quick judgment. To help us do this, our minds have developed little shortcuts to help us immediately understand our surroundings. These are called heuristics.

Most of the time, these processes are very helpful, but the trouble is that our minds tend to overuse them. Applying them in situations for which they aren’t suited can lead us to make mistakes. To get a better understanding of what heuristics are and what mistakes they can lead to, we can examine two of their many types: the substitution heuristic and the availability heuristic.

How can you make predictions on whether certain things will happen?

One effective way is to keep the base rate in mind. This refers to a statistical base, which other statistics rely on. For example, imagine a large taxi company has 20 percent yellow cabs and 80 percent red cabs. That means the base rate for yellow taxi cabs is 20 percent and the base rate for red cabs is 80 percent. If you order a cab and want to guess its color, remember the base rates and you will make a fairly accurate prediction.

Our minds don’t remember experiences in a straightforward way. We have two different apparatuses, called memory selves, both of which remember situations differently.

First, there is the experiencing self, which records how we feel in the present moment. It asks the question: “How does it feel now?”

Our minds use different amounts of energy depending on the task. When there’s no need to mobilize attention and little energy is needed, we are in a state of cognitive ease. Yet, when our minds must mobilize attention, they use more energy and enter a state of cognitive strain.

These changes in the brain’s energy levels have dramatic effects on how we behave.

The way we judge ideas and approach problems is heavily determined by the way they are expressed to us. Slight changes to the details or focus of a statement or question can dramatically alter the way we address it.

A great example of this can be found in how we assess risk.

How do we as individuals make choices?

For a long time, a powerful and influential group of economists suggested that we made decisions based purely on rational argument. They argued that we all make choices according to utility theory, which states that when individuals make decisions, they look only at the rational facts and choose the option with the best overall outcome for them, meaning the most utility.

If utility theory doesn’t work, then what does?

One alternative is prospect theory, developed by the author.

In order to understand situations, our minds naturally use cognitive coherence; we construct complete mental pictures to explain ideas and concepts. For example, we have many images in our brain for the weather. We have an image for, say, summer weather, which might be a picture of a bright, hot sun bathing us in heat.

As well as helping us to understand things, we also rely on these images when making a decision.