The key ideas

Gut Feelings: The Intelligence of the Unconscious

Gerd Gigerenzer, 2007

A player catches a ball without knowing physics. Students who know less are more accurate at guessing which city is larger. A Nobel laureate invests his own money without using his own model. Gerd Gigerenzer shows which simple rules may underlie intuition and challenges those who primarily see it as a source of errors.

Who it is for

For anyone who often makes quick decisions and wants to understand when to trust their intuition and when to check it.

Intuition is a judgment that appears quickly in consciousness, whose underlying reasons we do not fully understand, but which is strong enough to act upon.

About the book

How does a player catch a high ball? Calculating where it will land requires knowing its speed, angle, wind, and spin. The player is unlikely to work all this out mentally. Yet the ball ends up in the glove.

Gerd Gigerenzer, a German psychologist at the Max Planck Institute in Berlin, answers this question in Gut Feelings. In his view, intuition often rests on simple rules the brain uses without telling us.

The book challenges an influential school of psychology that studies how quick judgments mislead us. Gigerenzer asks a different question: when does a simple rule work better than a complex calculation? Ahead are a ball, cities, doctors, a Nobel laureate, and an honest account of where this idea is disputed.

Idea 1. Catching a ball without calculating anything

Back to the ball. Gigerenzer describes experienced players unconsciously using one rule. Fix your gaze on the ball, start running, and adjust your speed so that the angle at which you look at the ball stays constant.

The rule does not tell you where the ball will land. It simply brings you to where the ball will be. The author calls this the gaze heuristic. A heuristic is a simple rule that helps you decide using only part of the available information.

The player usually cannot explain what they are doing. They will say, “I just feel it.”

You cross the road and judge an approaching car by sight. If it seems stationary in your field of view but grows larger, that is a reason to be alert. This is Livria’s analogy rather than an example from the book.

Intuition may rest on a quite specific rule we apply without being able to name it. Being unable to explain a decision does not mean nothing underlies it.

Read in Livria

About the author

Gerd Gigerenzer is a German psychologist who for many years directed the Center for Adaptive Behavior and Cognition at the Max Planck Institute for Human Development in Berlin. He heads the Harding Center for Risk Literacy.

All books by this author: Gerd Gigerenzer

Terms from the book

  • Heuristic: A simple decision rule that uses only some of the available information. It may help or mislead depending on the situation.
  • Gaze heuristic: A rule the author describes: keep the angle of your gaze on a moving object constant by adjusting your speed. It helps you reach where the object will be without calculating its trajectory.
  • Recognition heuristic: A rule: if you recognize one of two alternatives but not the other, choose the familiar one. It may work when familiarity correlates with what you are being asked about.
  • Fast-and-frugal tree: A sequence of a few questions in which you can stop and make a decision at each step. A term from research by Gigerenzer’s group.
  • Ecological rationality: Gigerenzer’s idea that a rule is reasonable not in itself, but to the extent that it fits the environment where it is applied.

All terms

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