Thinking, Fast and Slow

by Daniel Kahneman

The familiarity of one phrase in the statement sufficed to make the whole statement feel familiar, and therefore true. If you cannot remember the source of a statement, and have no way to relate it to other things you know, you have no option but to go with the sense of cognitive ease.

If you care about being thought credible and intelligent, do not use complex language where simpler language will do. My Princeton colleague Danny Oppenheimer refuted a myth prevalent among undergraduates about the vocabulary that professors find most impressive.

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. Participants

Finally, if you quote a source, choose one with a name that is easy to pronounce.

You read this correctly: performance was better with the bad font. Cognitive strain, whatever its source, mobilizes System 2, which is more likely to reject the intuitive answer suggested by System 1. The Pleasure of Cognitive Ease An article titled “Mind at Ease Puts a Smile on the Face” describes an experiment in which participants were briefly shown pictures of objects.

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.

As should be clear by now, System 1 can respond to impressions of events of which System 2 is unaware.

The mere exposure effect occurs, Zajonc claimed, because the repeated exposure of a stimulus is followed by nothing bad. Such a stimulus will eventually become a safety signal, and safety is good.

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

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.

Cognitive ease is both a cause and a consequence of a pleasant feeling.

“Familiarity breeds liking. This is a mere exposure effect.”

“I’m in a very good mood today, and my System 2 is weaker than usual. I should be extra careful.”

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

The model is constructed by associations that link ideas of circumstances, events, actions, and outcomes that co-occur with some regularity, either at the same time or within a relatively short interval.

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.

The prominence of causal intuitions is a recurrent theme in this book because people are prone to apply causal thinking inappropriately, to situations that require statistical reasoning. Statistical thinking derives conclusions about individual cases from properties of categories and ensembles. 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.

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.

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;

Uncertainty and doubt are the domain of System 2.

Gilbert proposed that understanding a statement must begin with an attempt to believe it: you must first know what the idea would mean if it were true.

Only then can you decide whether or not to unbelieve it.

when System 2 is otherwise engaged, we will believe almost anything. System 1 is gullible and biased to believe, System 2 is in charge of doubting and unbelieving, but System 2 is sometimes busy, and often lazy. Indeed, there is evidence that people are more likely to be influenced by empty persuasive messages, such as commercials, when they are tired and depleted.

A deliberate search for confirming evidence, known as positive test strategy, is also how System 2 tests a hypothesis.

If you like the president’s politics, you probably like his voice and his appearance as well. The tendency to like (or dislike) everything about a person—including things you have not observed—is known as the halo effect.

The sequence in which we observe characteristics of a person is often determined by chance. Sequence matters, however, because the halo effect increases the weight of first impressions, sometimes to the point that subsequent information is mostly wasted.

To derive the most useful information from multiple sources of evidence, you should always try to make these sources independent of each other.

The combination of a coherence-seeking System 1 with a lazy System 2 implies that System 2 will endorse many intuitive beliefs, which closely reflect the impressions generated by System 1.

However, System 1 is expected to influence even the more careful decisions. Its input never ceases.

It is the consistency of the information that matters for a good story, not its completeness.

you will often find that knowing little makes it easier to fit everything you know into a coherent pattern.

Overconfidence: As the WYSIATI rule implies, neither the quantity nor the quality of the evidence counts for much in subjective confidence.

Framing effects: Different ways of presenting the same information often evoke different emotions. The

Base-rate neglect:

System 2 receives questions or generates them: in either case it directs attention and searches memory to find the answers. System 1 operates differently. It continuously monitors what is going on outside and inside the mind, and continuously generates assessments of various aspects of the situation without specific intention and with little or no effort. These basic assessments play an important role in intuitive judgment, because they are easily substituted for more difficult questions—this is the essential idea of the heuristics and biases approach.

Two other features of System 1 also support the substitution of one judgment for another. One is the ability to translate values across dimensions,

Finally, there is the mental shotgun. An intention of System 2 to answer a specific question or evaluate a particular attribute of the situation automatically triggers other computations, including basic assessments.

System 1 has been shaped by evolution to provide a continuous assessment of the main problems that an organism must solve to survive: How are things going? Is there a threat or a major opportunity? Is everything normal? Should I approach or avoid?

Good mood and cognitive ease are the human equivalents of assessments of safety and familiarity.

Alex Todorov, my colleague at Princeton, has explored the biological roots of the rapid judgments of

He showed that we are endowed with an ability to evaluate, in a single glance at a stranger’s face, two potentially crucial facts about that person: how dominant (and therefore potentially threatening) he is, and how trustworthy he is, whether his intentions are more likely to be friendly or hostile.

Todorov has found that people judge competence by combining the two dimensions of strength and trustworthiness. The faces that exude competence combine a strong chin with a slight confident-appearing smile.

Political scientists followed up on Todorov’s initial research by identifying a category of voters for whom the automatic preferences of System 1 are particularly likely to play a large role. They found what they were looking for among politically uninformed voters who watch a great deal of television. As expected, the effect of facial competence on voting is about three times larger for information-poor and TV-prone voters than for others who are better informed and watch less television. Evidently,

we often compute much more than we want or need. I call this excess computation the mental shotgun. It is impossible to aim at a single point with a shotgun because it shoots pellets that scatter,

“Evaluating people as attractive or not is a basic assessment. You do that automatically whether or not you want to, and it influences you.”

If a satisfactory answer to a hard question is not found quickly, System 1 will find a related question that is easier and will answer it. I call the operation of answering one question in place of another substitution.

The technical definition of heuristic is a simple procedure that helps find adequate, though often imperfect, answers to difficult questions.

“If you can’t solve a problem, then there is an easier problem you can solve: find it.”

Another capability of System 1, intensity matching, is available to solve that problem. Recall

The automatic processes of the mental shotgun and intensity matching often make available one or more answers to easy questions that could be mapped onto the target question.