Introduction

"Isn’t more information always better?" asks Gerd Gigerenzer. "Why else would bestsellers on how to make good decisions tell us to consider all pieces of information, weigh them carefully, and compute the optimal choice, preferably with the aid of a fancy statistical software package? In economics, Nobel prizes are regularly awarded for work that assumes that people make decisions as if they had perfect information and could compute the optimal solution for the problem at hand. But how do real people make good decisions under the usual conditions of little time and scarce information? Consider how players catch a ball—in baseball, cricket, or soccer. It may seem that they would have to solve complex differential equations in their heads to predict the trajectory of the ball. In fact, players use a simple heuristic. When a ball comes in high, the player fixates the ball and starts running. The heuristic is to adjust the running speed so that the angle of gaze remains constant —that is, the angle between the eye and the ball. The player can ignore all the information necessary to compute the trajectory, such as the ball’s initial velocity, distance, and angle, and just focus on one piece of information, the angle of gaze."

Gigerenzer provides an alternative to the view of the mind as a cognitive optimizer, and also to its mirror image, the mind as a cognitive miser. The fact that people ignore information has been often mistaken as a form of irrationality, and shelves are filled with books that explain how people routinely commit cognitive fallacies. In seven years of research, he, and his research team at Center for Adaptive Behavior and Cognition at the Max Planck Institute for Human Development in Berlin, have worked out what he believes is a viable alternative: the study of fast and frugal decision-making, that is, the study of smart heuristics people actually use to make good decisions. In order to make good decisions in an uncertain world, one sometimes has to ignore information. The art is knowing what one doesn’t have to know.

Gigerenzer's work is of importance to people interested in how the human mind actually solves problems. In this regard his work is influential to psychologists, economists, philosophers, and animal biologists, among others. It is also of interest to people who design smart systems to solve problems; he provides illustrations on how one can construct fast and frugal strategies for coronary care unit decisions, personnel selection, and stock picking.

"My work will, I hope, change the way people think about human rationality", he says. "Human rationality cannot be understood, I argue, by the ideals of omniscience and optimization. In an uncertain world, there is no optimal solution known for most interesting and urgent problems. When human behavior fails to meet these Olympian expectations, many psychologists conclude that the mind is doomed to irrationality. These are the two dominant views today, and neither extreme of hyper-rationality or irrationality captures the essence of human reasoning. My aim is not so much to criticize the status quo, but rather to provide a viable alternative."

—JB

GERD GIGERENZER is Director of the Center for Adaptive Behavior and Cognition at the Max Planck Institute for Human Development in Berlin and former Professor of Psychology at the University of Chicago. He won the AAAS Prize for the best article in the behavioral sciences. He is the author of Calculated Risks: How To Know When Numbers Deceive You, the German translation of which won the Scientific Book of the Year Prize in 2002. He has also published two academic books on heuristics, Simple Heuristics That Make Us Smart (with Peter Todd & The ABC Research Group) and Bounded Rationality: The Adaptive Toolbox (with Reinhard Selten, a Nobel laureate in economics).

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