Simple Heuristics That Make Us Smart

433 Pages·2000·21.57 MB·English

by  Gerd Gigerenzer

Simple Heuristics
That Make Us Smart
EVOLUTION AND COGNITION
General Editor. Stephen Stich, Rutgers University
Published in the Series
Simple Heuristics That Make Us Smart
Gerd Gigerenzer, Peter M. Todd, and the ABC Research Group
Simple Heuristics
That Make
Us Smart
Gerd Gigerenzer
Peter M. Todd
and the ABC Research Group
OXFORD
UNIVERSITY PRESS
OXFORD
UNIVERSITY PRESS
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Copyright © 1999 by Oxford University Press, Inc.
First published in 1999 by Oxford University Press, Inc.
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First issued as an Oxford University Press paperback, 2001
Oxford is a registered trademark of Oxford University Press
All rights reserved. No part of this publication may be reproduced,
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Library of Congress Cataloging-in-Publication Data
Gigerenzer, Gerd.
Simple heuristics that make us smart / Gerd Gigerenzer, Peter M.
Todd, and the ABC Research Group.
p. cm.
Includes bibliographical references and indexes.
ISBN 0-19-512156-2; ISBN 0-19-514381-7 (pbk.)
1. Heuristic. I. Todd, Peter M. II. ABC Research Group.
III. Title.
BD260.G54 1999
128'.33—dc21 98-51084
9 8 7 6
Printed in the United States of America
on acid-free paper
Dedicated, simply, to our families.
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Preface
I his book is an invitation to participate in a journey into largely un-
known territory. The journey ventures into a land of rationality that is
different from the familiar one we know from many stories in cognitive
science and economics—tales in which humans live in a world with un-
limited time and knowledge, where the sun of enlightenment shines down
in beams of logic and probability. The new land of rationality we set out
to explore is, in contrast, shrouded in a mist of dim uncertainty. People
in this world have only limited time, knowledge, and computational ca-
pacities with which to make inferences about what happens in the enig-
matic places in their world.
How can one be rational in a world where vision is limited, time is
pressing, and decision-making experts are often unavailable? In this book
we argue that rationality can be found in the use of fast and frugal heuris-
tics, inference mechanisms that can be simple and smart. The laws of
logic and probability play little if any role in the performance of these
components of the mind's adaptive toolbox—these heuristics are success-
ful to the degree they are ecologically rational, that is, adapted to the
structure of the information in the environment in which they are used to
make decisions.
We set out on this journey as a disparate group of people from various
fields that often do not talk to each other, including psychology, mathe-
matics, computer science, economics, and evolutionary biology. The trick
viii PREFACE
was to put everyone in one boat, where there was no escape from talking
and working together or from learning the language and the skills of the
others. The boat and its long-term funding was provided by the unique
policy of the Max Planck Society, which allowed us to take on a challeng-
ing project with an uncertain outcome by adopting a research perspective
of many, many years. Much of the exploration described in this book was
carried out at the Max Planck Institute for Psychological Research in Mu-
nich; further forays into the vast unexplored territory of ecological ration-
ality have taken place in our new home at the Max Planck Institute for
Human Development in Berlin. We have only been on our journey for
fewer than three years, but in that time we have seen new horizons and
made new discoveries in the world of heuristics, making the time right
for a first report from the field.
Our group's name, the ABC research group, is short for the Center for
Adaptive Behavior and Cognition. This name also has a second meaning
that is central to the topic of this book: We study the ABCs of decision-
making heuristics—that is, the basic building blocks from which these
inference mechanisms are made.
The chapters in this book tell the story of our explorations in a way
that reflects our feelings and mounting excitement during the long trek.
We stumbled over the surprising performance of a variety of simple heu-
ristics, and the reasons behind their successful behavior, only after long
and painful stretches of lack of insight and failed conjectures. We started
off believing our results just could not be true (a sentiment many of our
colleagues were quick to share, and slower than we to abandon), only to
end up realizing that there are good reasons for these findings to be true.
To reflect our progress from bafflement and disbelief to happy certainty,
some early chapters will report our first puzzling findings, while later
chapters will put the pieces together into the bigger picture.
This book is meant to excite and inspire intellectual adventurers who
love to explore and dare rather than playing it safe and sticking to re-
ceived wisdom. This is not to say that we present only daring, unwise
results—we marshal the evidence of experiments, real-world simulations,
and the safe haven of proofs. But we have also undertaken bold adven-
tures, such as the (lucrative) decision to throw one of our heuristics at the
stock market to see whether it could make any money.
We have made forays into several different regions of the new territory
of ecological rationality, from the chaos of the stock market to the intrica-
cies of mate choice. But what is most important is the guiding vision that
has given us the overall direction that we follow. We may have seen only
the coastal regions of the new territory, and we may have placed some of
the heuristics mistakenly on our growing map, but we believe that the
land of fast and frugal heuristics is the right direction in which to head.
The individual chapters in this book are all multiauthored, reflecting
the interdisciplinary collaboration among researchers that gave birth to
each separate expedition. Successful interdisciplinary collaboration is still
PREFACE ix
a rare event even in these days of proliferating interdisciplinary groups.
Part of our success came from the attitudes that the individual researchers
brought with them: After an initial phase of puzzlement ("What could I
learn from a mathematician?"), intellectual curiosity and trust—that is,
the feeling that one can challenge and disagree but still be respected and
remain friends—won out. Also crucial, though, was establishing an envi-
ronment in which these attitudes could evolve: everyone with offices near
each other and the doors left open, and coffee and tea every afternoon at
4 P.M. These are some of the features that made our journey enjoyable as
well as productive.
Any journey into new territory must build upon the past explorations
of others, and draw upon the knowledge and guidance of current adven-
turesome experts. We have been inspired both by the ideas, and by the
title, of Donald Norman's book Things That Make Us Smart (1993). We
are grateful to our colleagues who read through drafts of earlier versions
of individual chapters and gave us helpful feedback: Gregory Ashby, Peter
Ayton, Talia Ben-Zeev, Jim Bettman, Greg Brake, Arndt Broder, Ed Buk-
szar, Nick Chater, Edgar Erdfelder, Klaus Fiedler, Bruno Frey, William M.
Goldstein, Karl Grammer, Nigel Harvey, Reid Hastie, Wolfgang Hell, Os-
wald Huber, Helmut Jungermann, Peter Juslin, Timothy Ketelaar, Jack
Knetsch, Asher Koriat, Jane Lancaster, Pat Langley, Barbara Mellers, Rich-
ard Nisbett, Richard Olsen, John Payne, Stuart Russell, Peter Sedlmeier,
Thor Sigvaldason, Tom Stewart, Richard Thaler, Ryan Tweney, Kim Vi-
cente, Tom Wallsten, X. T. Wang, Elke Weber, and Kevin Weinfurt.
Special thanks go to Valerie M. Chase, Elke Kurz, Catrin Rode, and
William Wimsatt, who read drafts of the entire book, and to Donna Alex-
ander, Andreas Deters, Martin Dieringer, Timmo Kohler, Ulrich Kuhnert,
Torsten Mohrbach, Marianne Muller-Brettel, Brady Richards, Rudiger
Sparr, Anita Todd, Ahn Vu, and Jill Vyse, who helped us with collecting
data and editing the manuscript.
This book is the starting point of an ongoing research program; for fur-
ther developments and results, we invite you to visit our Center's website
at http://www.mpib-berlin.mpg.de/abc/.
Welcome to our journey.
Berlin Gerd Gigerenzer
July 1998 Peter Todd