Thinking, Fast and Slow

Thinking, Fast and Slow

by

Daniel Kahneman

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Müller-Lyer Illusion Symbol Analysis

Müller-Lyer Illusion Symbol Icon

The Müller-Lyer illusion symbolizes people’s inability to change how they process information, even when they know they are wrong. The Müller-Lyer illusion is an image: on the top is a horizontal line with arrows or fins attached to it that point outward, away from the line. On the bottom is another horizontal line with arrows or fins that point inward, towards the line. Measuring would reveal that the two horizontal lines are the same, but the horizontal line in the bottom figure always appears longer. Even though we learn that the two lines are equally long, that is not our automatic intuition about them.

This illusion then becomes a good stand-in for what Kahneman calls “cognitive illusions.” Like the Müller-Lyer illusion, there are cognitive illusions in which, even though people learn what the real answer to a puzzle might be, their intuition will still tell them that a different answer is the correct one. Kahneman’s purpose in writing the book, then, is to help people learn the illusions—like Müller-Lyer—in which they might make a mistake, and to remind them to expend a little more effort in calculating their answers and making decisions.

Müller-Lyer Illusion Quotes in Thinking, Fast and Slow

The Thinking, Fast and Slow quotes below all refer to the symbol of Müller-Lyer Illusion. For each quote, you can also see the other characters and themes related to it (each theme is indicated by its own dot and icon, like this one:
Intuition, Deliberation, and Laziness Theme Icon
). Note: all page numbers and citation info for the quotes below refer to the Farrar, Straus and Giroux edition of Thinking, Fast and Slow published in 2011.
Part 2, Chapter 15 Quotes

The set of feminist bank tellers is wholly included in the set of bank tellers, as every feminist bank teller is a bank teller. Therefore the probability that Linda is a feminist bank teller must be lower than the probability of her being a bank teller. […] The problem therefore sets up a conflict between the intuition of representativeness and the logic of probability.

Related Characters: Daniel Kahneman (speaker)
Related Symbols: Müller-Lyer Illusion
Page Number: 157
Explanation and Analysis:
Part 3, Chapter 20 Quotes

The illusion of skill is not only an individual aberration; it is deeply ingrained in the culture of the industry. Facts that challenge such basic assumptions—and thereby threaten people’s livelihood and self-esteem—are simply not absorbed.

Related Characters: Daniel Kahneman (speaker)
Related Symbols: Müller-Lyer Illusion
Page Number: 216
Explanation and Analysis:
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Müller-Lyer Illusion Symbol Timeline in Thinking, Fast and Slow

The timeline below shows where the symbol Müller-Lyer Illusion appears in Thinking, Fast and Slow. The colored dots and icons indicate which themes are associated with that appearance.
Part 1, Chapter 1
Intuition, Deliberation, and Laziness Theme Icon
Kahneman next introduces illusions, including a famous image called the Müller-Lyer illusion . It shows two figures: on the top is a horizontal line with arrows or... (full context)
Intuition, Deliberation, and Laziness Theme Icon
The Müller-Lyer illusion is an example of a visual illusion, but there are cognitive illusions as well. As... (full context)
Conclusions
Intuition, Deliberation, and Laziness Theme Icon
...and ask for reinforcement from System 2.” This is what occurs when we encounter the Müller-Lyer illusion after we have learned that our intuition is incorrect. (full context)