Thinking, Fast and Slow

by Daniel Kahneman

The assessments are carried out automatically by System 1, and one of their functions is to determine whether extra effort is required from System 2.

The various causes of ease or strain have interchangeable effects.

Jacoby nicely stated the problem: “The experience of familiarity has a simple but powerful quality of ‘pastness’ that seems to indicate that it is a direct reflection of prior experience.” This quality of pastness is an illusion.

Words that you have seen before become easier to see again—you can identify them better than other words when they are shown very briefly or masked by noise, and you will be quicker (by a few hundredths of a second) to read them than to read other words.

But there were questions where no good answer came to mind, where all I had to go by was cognitive ease. If the answer felt familiar, I assumed that it was probably true. If it looked new (or improbably extreme), I rejected it.

The impression of familiarity is produced by System 1, and System 2 relies on that impression for a true/false judgment.

Anything that makes it easier for the associative machine to run smoothly will also bias beliefs.

A reliable way to make people believe in falsehoods is frequent repetition, because familiarity is not easily distinguished from truth. Authoritarian institutions and marketers have always known this fact.

The familiarity of one phrase in the statement sufficed to make the whole statement feel familiar, and therefore true.

The general principle is that anything you can do to reduce cognitive strain will help, so you should first maximize legibility.

If you use color, you are more likely to be believed if your text is printed in bright blue or red than in middling shades of green, yellow, or pale blue.

do not use complex language where simpler language will do.

In addition to making your message simple, try to make it memorable. Put your ideas in verse if you can; they will be more likely to be taken as truth.

Remember that System 2 is lazy and that mental effort is aversive.

This is the message of figure 5: the sense of ease or strain has multiple causes, and it is difficult to tease them apart. Difficult, but not impossible. People can overcome some of the superficial factors that produce illusions of truth when strongly motivated to do so. On most occasions, however, the lazy System 2 will adopt the suggestions of System 1 and march on.

Cognitive strain, whatever its source, mobilizes System 2, which is more likely to reject the intuitive answer suggested by System 1.

repetition induces cognitive ease and a comforting feeling of familiarity.

Zajonc called it the mere exposure effect.

The mere exposure effect does not depend on the conscious experience of familiarity. In fact, the effect does not depend on consciousness at all: it occurs even when the repeated words or pictures are shown so quickly that the observers never become aware of having seen them. They still end up liking the words or pictures that were presented more frequently.

the mere exposure effect is actually stronger for stimuli that the individual never consciously sees.

A sense of cognitive ease is apparently generated by a very faint signal from the associative machine, which “knows” that the three words are coherent (share an association) long before the association is retrieved.

They found that putting the participants in a good mood before the test by having them think happy thoughts more than doubled accuracy. An even more striking result is that unhappy subjects were completely incapable of performing the intuitive task accurately; their guesses were no better than random.

Mood evidently affects the operation of System 1: when we are uncomfortable and unhappy, we lose touch with our intuition.

A happy mood loosens the control of System 2 over performance: when in a good mood, people become more intuitive and more creative but also less vigilant and more prone to logical errors.

The impression of cognitive ease that comes with the presentation of a coherent triad appears to be mildly pleasurable in itself.

Cognitive ease and smiling occur together, but do the good feelings actually lead to intuitions of coherence? Yes, they do.

The main function of System 1 is to maintain and update a model of your personal world, which represents what is normal in it.

There are two main varieties of surprise. Some expectations are active and conscious—

You will be surprised if an actively expected event does not occur.

you don’t wait for them, but you are not surprised when they happen. These are events that are normal in a situation, though not sufficiently probable to be actively expected.

Under some conditions, passive expectations quickly turn active,

Studies of brain responses have shown that violations of normality are detected with astonishing speed and subtlety.

We have norms for a vast number of categories, and these norms provide the background for the immediate detection of anomalies such as pregnant men and tattooed aristocrats.

System 1, which understands language, has access to norms of categories, which specify the range of plausible values as well as the most typical cases.

Finding such causal connections is part of understanding a story and is an automatic operation of System 1. System 2, your conscious self, was offered the causal interpretation and accepted it.

a statement that can explain two contradictory outcomes explains nothing at all.

Michotte had a different idea: he argued that we see causality, just as directly as we see color.

the perception of intentional causality.

The perception of intention and emotion is irresistible; only people afflicted by autism do not experience it.

Your mind is ready and even eager to identify agents, assign them personality traits and specific intentions, and view their actions as expressing individual propensities.

The experience of freely willed action is quite separate from physical causality.

The psychologist Paul Bloom, writing in The Atlantic in 2005, presented the provocative claim that our inborn readiness to separate physical and intentional causality explains the near universality of religious beliefs.

In Bloom’s view, the two concepts of causality were shaped separately by evolutionary forces, building the origins of religion into the structure of System 1.

people are prone to apply causal thinking inappropriately, to situations that require statistical reasoning.

Unfortunately, System 1 does not have the capability for this mode of reasoning; System 2 can learn to think statistically, but few people receive the necessary training.

The system and the machine are fictions; my reason for using them is that they fit the way we think about causes.

Jumping to conclusions is efficient if the conclusions are likely to be correct and the costs of an occasional mistake acceptable, and if the jump saves much time and effort. Jumping to conclusions is risky when the situation is unfamiliar, the stakes are high, and there is no time to collect more information.

When uncertain, System 1 bets on an answer, and the bets are guided by experience.

System 1 does not keep track of alternatives that it rejects, or even of the fact that there were alternatives.

Conscious doubt is not in the repertoire of System 1; it requires maintaining incompatible interpretations in mind at the same time, which demands mental effort. Uncertainty and doubt are the domain of System 2.