A summary of: Thinking, Fast and Slow. It is a 2011 book by psychologist Daniel Kahneman.

The book's main thesis is that of a dichotomy between two modes of thought: "System 1" is fast, instinctive and emotional; "System 2" is slower, more deliberative, and more logical. The book delineates rational and non-rational motivations or triggers associated with each type of thinking process, and how they complement each other, starting with Kahneman's own research on loss aversion. From framing choices to people's tendency to replace a difficult question with one which is easy to answer, the book summarizes several decades of research to suggest that people have too much confidence in human judgement. Kahneman performed his own research, often in collaboration with Amos Tversky, which enriched his experience to write the book. It covers different phases of his career: his early work concerning cognitive biases, his work on prospect theory and happiness, and with the Israel Defense Forces.

The integrity of many of the priming studies cited in the book have been called into question in the midst of the psychological replication crisis, although the results of Kahneman's own studies have been replicated.[citation needed]

The book was a New York Times bestseller and was the 2012 winner of the National Academies Communication Award for best creative work that helps the public understanding of topics in behavioral science, engineering and medicine.

In the book's first section, Kahneman describes two different ways the brain forms thoughts:

System 1: Fast, automatic, frequent, emotional, stereotypic, unconscious. Examples (in order of complexity) of things system 1 can do:
determine that an object is at a greater distance than another
localize the source of a specific sound
complete the phrase "war and ..."
display disgust when seeing a gruesome image
solve 2+2=?
read text on a billboard
drive a car on an empty road
think of a good chess move (if you're a chess master)
understand simple sentences
associate the description 'quiet and structured person with an eye for details' with a specific job
System 2: Slow, effortful, infrequent, logical, calculating, conscious. Examples of things system 2 can do:
prepare yourself for the start of a sprint
direct your attention towards the clowns at the circus
direct your attention towards someone at a loud party
look for the woman with the grey hair
try to recognize a sound
sustain a faster-than-normal walking rate
determine the appropriateness of a particular behavior in a social setting
count the number of A's in a certain text
give someone your telephone number
park into a tight parking space
determine the price/quality ratio of two washing machines
determine the validity of a complex logical reasoning
solve 17 × 24

Content:
INTRODUCTION
PART 1: TWO SYSTEMS
1: THE CHARACTERS OF THE STORY
2: ATTENTION AND EFFORT
3: THE LAZY CONTROLLER
4: THE ASSOCIATIVE MACHINE
5: COGNITIVE EASE
6: NORMS, SURPRISES, AND CAUSES
7: A MACHINE FOR JUMPING TO CONCLUSIONS
9: ANSWERING AN EASIER QUESTION
PART 2: HEURISTICS AND BIASES
10: THE LAW OF SMALL NUMBERS
11: ANCHORING EFFECTS
12: THE SCIENCE OF AVAILABILITY
13: AVAILABILITY, EMOTION, AND RISK
14: TOM W’S SPECIALTY
15: LINDA: LESS IS MORE
17: REGRESSION TO THE MEAN
18: TAMING INTUITIVE PREDICTIONS
PART 3: OVERCONFIDENCE
19: THE ILLUSION OF UNDERSTANDINGCHAPTER
20: THE ILLUSION OF VALIDITY
21: INTUITIONS VS. FORMULAS
22: EXPERT INTUITION: WHEN CAN WE TRUST IT?
23: THE OUTSIDE VIEW
24: THE ENGINE OF CAPITALISM
PART 4: CHOICES
25: BERNOULLI’S ERROR
26: PROSPECT THEORY
27: THE ENDOWMENT EFFECT
28: BAD EVENTS
29: THE FOURFOLD PATTERN
30: RARE EVENTS
31: RISK POLICIES
32: KEEPING SCORE
33: REVERSALS
34: FRAMES AND REALITY
PART 5: TWO SELVES
35: TWO SELVES
37: EXPERIENCED WELL-BEING
38: THINKING ABOUT LIFE