Review by Bruce Bower

By Christopher Chabris and Daniel Simons

Web edition: June 18, 2010
Print edition: July 3, 2010; Vol.178 #1 (p. 30)

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The Invisible Gorilla: And Other Ways Our Intuitions Deceive Us by Christopher Chabris and Daniel Simons

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People wearing gorilla suits don’t always stand out in a crowd. When volunteers were asked to count the number of ball passes made by a basketball team in a video, half never noticed a gorilla-suited intruder walking across the court doing chest thumps.

That experiment, conducted by psychologists Chabris and Simons in 1999, launches their book about the dangers of trusting one’s intuitive assumptions, unsullied by rational deliberations, of how the mind works. Invisible gorillas are an example of what the authors call “the illusion of attention,” in which people miss objects because their attention is focused tightly elsewhere.

Other mental illusions get similarly assessed. Studies show that personal memories, such as how and where one learned of 9/11, change over time. Even vivid memories that seem true to life can be distorted or entirely false, the authors say. Other evidence indicates that people overestimate their skills and abilities, from competitive chess players to American Idol contestants. And people regularly think that they know more than they do, resulting in disastrous financial investments and other catastrophes, Chabris and Simons note.

The authors belong to a psychological school of thought that celebrates methodical, rational analysis over rapid, intuitive decision making. They say little about research that has revealed intuition’s strengths, such as its ability to aid firefighters, pilots and other professionals in making critical decisions under time pressure. Nor do the authors address the possibility that experimentally induced mental illusions stem from thinking strategies that are generally useful, just as optical illusions stem from a largely effective visual system.

Still, the book, unlike the fake gorilla, will not go unnoticed. 

Crown Publishing, 2010, 306 p., $27.