Book Review: The Invisible Gorilla by Chabris and Simons

Introduction: Six Illusions That Deceive the Brain

Blending pop psychology with cognitive science, Christopher Chabris and Daniel Simons write about perceptual biases and inattentional blindness in The Invisible Gorilla. Sparked by a now-famous experiment the authors performed, The Invisible Gorilla: How Our Intuitions Deceive Us is not as much about intuition as the subtitle suggests. Rather, the book describes six ways our brains are fooled by illusions. Recognizing and understanding these illusions can prevent people from making critical mistakes in judgment. Those mistakes can sometimes be egregious — as when police presume a Black man is a criminal, or when drivers overestimate their ability to multitask on the road. Salesmen and stage magicians count on the brain's susceptibility to illusion to succeed. Memories of past events are reconstructions rather than accurate recordings of fact. The main reason Chabris and Simons translated their research findings into a popular book written for a general audience is to encourage all people to be more aware of their biases and work harder to overcome them.

The Gorilla Experiment and Inattentional Blindness

The title of The Invisible Gorilla comes from the landmark experiment in which the authors ask subjects to concentrate on counting the number of basketball passes made by one team. The act of concentrating diverts attention away from the entire visual field, so that when a man in a gorilla suit walks through the scene, about half the participants fail to notice. Chabris and Simons call this phenomenon inattentional blindness because the individual is perceptually blind to the gorilla due to not paying full attention. The original experiment, published in 1999 in the peer-reviewed journal Perception, won awards and has had significant impact in fields such as law enforcement.

Lack of attention or awareness is a major problem with real consequences — including, as the authors demonstrate, actual fatalities. The six examples used in The Invisible Gorilla illustrate the different ways inattentional blindness and related cognitive and perceptual biases can cause serious problems. The authors imply that the evidence presented in the book can be used to inform public policy.

Inattentional Blindness and Real-World Consequences

The Invisible Gorilla is divided into six chapters, plus an introduction and conclusion. Each of the six main chapters is devoted to a discussion of a type of cognitive-perceptual illusion with real-world consequences. The authors open the book with a chapter called "I Think I Would Have Seen That," which concerns the ways inattentional blindness can contribute to racial stereotyping. Using the real-life example of the assault on Michael Cox in Boston, the authors show how many people develop a false sense of confidence in their own perceptual skills. This was especially true for Conley, who was convicted of the assault on fellow officer Michael Cox.

The authors hypothesize that Conley missed the assault on Cox for the same reasons research participants miss the gorilla. The gorilla experiment was never introduced in court to aid Conley's appeal, but the authors suggest that cognitive science research on inattentional blindness can and should be incorporated in similar cases — to help juries understand that people make mistakes not because they are incompetent, but simply because of the way the brain works. Furthermore, knowing that inattentional blindness occurs, law enforcement training programs could be improved to help minimize the problem.

Chabris and Simons bridge the results of the gorilla experiment with their concept of intuition. Perhaps the weakest part of The Invisible Gorilla is the assumption that intuition is what caused prosecutors, jurors, and investigators to presume Conley's guilt. In fact, it was not intuition but the facts of the case: Conley was present; Conley was the officer in charge. Therefore, Conley should have noticed that one of his own men was being assaulted. Intuition or gut instinct is not what caused either the assault on Cox or the conviction of Conley. Essentially, Chabris and Simons mistake intuition for imperfect judgment. In spite of this weakness, The Invisible Gorilla conveys sound evidence on the causes and effects of perceptual and cognitive illusions and biases. The authors also show how anecdotal evidence is problematic — not just because it is anecdotal and not based on documented fact, but also because the recipient places undue importance on the relevance and power of anecdote. Learning to distinguish fact from fiction and to think more critically is the core lesson of The Invisible Gorilla.

Works Cited

Chabris, Christopher and Daniel Simons. The Invisible Gorilla: How Our Intuitions Deceive Us. New York: Random House, 2009.