Thinking, Fast and Slow

by Daniel Kahneman

The mental work that produces impressions, intuitions, and many decisions goes on in silence in our mind.

We are often confident even when we are wrong, and an objective observer is more likely to detect our errors than we are.

improve the ability to identify and understand errors of judgment and choice, in others and eventually in ourselves, by providing a richer and more precise language to discuss them.

People tend to assess the relative importance of issues by the ease with which they are retrieved from memory—and this is largely determined by the extent of coverage in the media.

A recurrent theme of this book is that luck plays a large role in every story of success; it is almost always easy to identify a small change in the story that would have turned a remarkable achievement into a mediocre outcome.

situation has provided a cue; this cue has given the expert access to information stored in memory, and the information provides the answer. Intuition is nothing more and nothing less than recognition.”

The executive’s decision would today be described as an example of the affect heuristic, where judgments and decisions are guided directly by feelings of liking and disliking, with little deliberation or reasoning.

intuitive heuristics: when faced with a difficult question, we often answer an easier one instead, usually without noticing the substitution.

1 The Characters of the Story

System 1 operates automatically and quickly, with little or no effort and no sense of voluntary control. System 2 allocates attention to the effortful mental activities that demand it, including complex computations. The operations of System 2 are often associated with the subjective experience of agency, choice, and concentration.

The highly diverse operations of System 2 have one feature in common: they require attention and are disrupted when attention is drawn away.

The gorilla study illustrates two important facts about our minds: we can be blind to the obvious, and we are also blind to our blindness.

System 1 continuously generates suggestions for System 2: impressions, intuitions, intentions, and feelings. If endorsed by System 2, impressions and intuitions turn into beliefs, and impulses turn into voluntary actions. When all goes smoothly, which is most of the time, System 2 adopts the suggestions of System 1 with little or no modification. You generally believe your impressions and act on your desires, and that is fine—usually.

In summary, most of what you (your System 2) think and do originates in your System 1, but System 2 takes over when things get difficult, and it normally has the last word.

In other words, System 2 is in charge of self-control.

illusions of thought, which we call cognitive illusions.

The best we can do is a compromise: learn to recognize situations in which mistakes are likely and try harder to avoid significant mistakes when the stakes are high.

The premise of this book is that it is easier to recognize other people’s mistakes than our own.

The premise of the book is that it is easier to recognize other peoples mistakes than your own.

The mind—especially System 1—appears to have a special aptitude for the construction and interpretation of stories about active agents, who have personalities, habits, and abilities.

The defining feature of System 2, in this story, is that its operations are effortful, and one of its main characteristics is laziness, a reluctance to invest more effort than is strictly necessary. As a consequence, the thoughts and actions that System 2 believes it has chosen are often guided by the figure at the center of the story, System 1.

Even in modern humans, System 1 takes over in emergencies and assigns total priority to self-protective actions.

A general “law of least effort” applies to cognitive as well as physical exertion. The law asserts that if there are several ways of achieving the same goal, people will eventually gravitate to the least demanding course of action. In the economy of action, effort is a cost, and the acquisition of skill is driven by the balance of benefits and costs. Laziness is built deep into our nature.

System 2 is the only one that can follow rules, compare objects on several attributes, and make deliberate choices between options. The automatic System 1 does not have these capabilities.

System 1 detects simple relations (“they are all alike,” “the son is much taller than the father”) and excels at integrating information about one thing, but it does not deal with multiple distinct topics at once, nor is it adept at using purely statistical information.

A crucial capability of System 2 is the adoption of “task sets”: it can program memory to obey an instruction that overrides habitual responses.

Psychologists speak of “executive control” to describe the adoption and termination of task sets, and neuroscientists have identified the main regions of the brain that serve the executive function.

One of the significant discoveries of cognitive psychologists in recent decades is that switching from one task to another is effortful, especially under time pressure.

Time pressure is another driver of effort.

The most effortful forms of slow thinking are those that require you to think fast.

Speaking of Attention and Effort “I won’t try to solve this while driving. This is a pupil-dilating task. It requires mental effort!” “The law of least effort is operating here. He will think as little as possible.” “She did not forget about the meeting. She was completely focused on something else when the meeting was set and she just didn’t hear you.” “What came quickly to my mind was an intuition from System 1. I’ll have to start over and search my memory deliberately.”

Self-control and deliberate thought apparently draw on the same limited budget of effort.

Flow neatly separates the two forms of effort: concentration on the task and the deliberate control of attention.

It is now a well-established proposition that both self-control and cognitive effort are forms of mental work. Several psychological studies have shown that people who are simultaneously challenged by a demanding cognitive task and by a temptation are more likely to yield to the temptation.

System 1 has more influence on behavior when System 2 is busy,

People who are cognitively busy are also more likely to make selfish choices, use sexist language, and make superficial judgments in social situations.

The conclusion is straightforward: self-control requires attention and effort. Another way of saying this is that controlling thoughts and behaviors is one of the tasks that System 2 performs.

an effort of will or self-control is tiring; if you have had to force yourself to do something, you are less willing or less able to exert self-control when the next challenge comes around. The phenomenon has been named ego depletion.

The evidence is persuasive: activities that impose high demands on System 2 require self-control, and the exertion of self-control is depleting and unpleasant. Unlike cognitive load, ego depletion is at least in part a loss of motivation. After exerting self-control in one task, you do not feel like making an effort in another, although you could do it if you really had to.

The bold implication of this idea is that the effects of ego depletion could be undone by ingesting glucose,

One of the main functions of System 2 is to monitor and control thoughts and actions “suggested” by System 1, allowing some to be expressed directly in behavior and suppressing or modifying others.

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

The bat-and-ball problem is our first encounter with an observation that will be a recurrent theme of this book: many people are overconfident, prone to place too much faith in their intuitions. They apparently find cognitive effort at least mildly unpleasant and avoid it as much as possible.

Intelligence is not only the ability to reason; it is also the ability to find relevant material in memory and to deploy attention when needed.

“personalities.” System 1 is impulsive and intuitive; System 2 is capable of reasoning, and it is cautious, but at least for some people it is also lazy. We recognize related differences among individuals: some people are more like their System 2; others are closer to their System 1.

Speaking of Control “She did not have to struggle to stay on task for hours. She was in a state of flow.” “His ego was depleted after a long day of meetings. So he just turned to standard operating procedures instead of thinking through the problem.” “He didn’t bother to check whether what he said made sense. Does he usually have a lazy System 2 or was he unusually tired?” “Unfortunately, she tends to say the first thing that comes into her mind. She probably also has trouble delaying gratification. Weak System 2.”

process called associative activation: ideas that have been evoked trigger many other ideas, in a spreading cascade of activity in your brain.

All this happens quickly and all at once, yielding a self-reinforcing pattern of cognitive, emotional, and physical responses that is both diverse and integrated—it has been called associatively coherent.

This remarkable priming phenomenon—the influencing of an action by the idea—is known as the ideomotor effect.

The general theme of these findings is that the idea of money primes individualism: a reluctance to be involved with others, to depend on others, or to accept demands from others.

Speaking of Priming “The sight of all these people in uniforms does not prime creativity.” “The world makes much less sense than you think. The coherence comes mostly from the way your mind works.” “They were primed to find flaws, and this is exactly what they found.” “His System 1 constructed a story, and his System 2 believed it. It happens to all of us.” “I made myself smile and I’m actually feeling better!”