Book Review: The Invisible Gorilla

If there is one book that every human should read, it is The Invisible Gorilla, by Chris Chabris and Dan Simons.


I suppose that's a pretty bold statement to make. Let me explain. As a student of psychology, and as someone who studies and writes about the mind, I am overwhelmed with the general perception among the lay public that "social science findings often reaffirm or echo what common sense observations tell us." But the truth is that common sense observations often lead us astray. We have very little insight into the way our minds actually operate. And the thing is, this is likely a feature of the system, rather than a bug.

If you've taken any introductory psychology class in the last decade or so, you've no doubt seen this demonstration. You will see six people - three in white shirts and three in black shirts - pass basketballs around. While you watch, you must keep a silent count of the number of passes made by the people in white shirts.

Did you see the gorilla? No? Watch it again. "But wait," you tell me, "I knew the gorilla was coming because I've seen this demonstration before!"

Fair enough.

Try this updated version.

This is a perceptual illusion, to be sure. You didn't notice the gorilla, or you didn't notice the color change, for example. But the real illusion here is a cognitive one. The illusion here is that if there was a gorilla - or if the color of the curtain on the stage did change - you are convinced, you are certain that you would have noticed. This is the true illusion. The illusion of attention. We think that if something occurs in our visual field, we will notice.

In their book, Chris and Dan discuss the illusion of attention at length, as well as the illusions of memory, confidence, knowledge, cause, and potential - all falling under the larger umbrella of illusions of intuition.

By using real-life examples from the news and from pop culture, they explain these common everyday illusions, and offer suggestions for how to overcome them. Not that its easy, of course. That these illusions are so pervasive is evidence of how integral they are in the organization of our minds.

How could a police officer run right past an assault without noticing? And be convinced that he had seen nothing? "I think I would have seen that," he would later testify in a courtroom. How does the illusion of cause contribute to the anti-vax movement? Could it be because the mind is built to detect meaning in random patterns, to infer causal relationships based on coincidences?

Often, in the comments in this blog and others, I find myself having to remind people that they have far less insight into the way their minds work, and the reasons they behave the way they do, than they think. And that's okay! But understanding why the mind is so susceptible to these cognitive illusions can help us understand how to avoid the dangers inherent in those illusions. I am so glad that now I can simply refer people to The Invisible Gorilla. And now, to repeat my initial statement: if there's one book that every human should study, it is this one.

Disclosure: I received a free copy of The Invisible Gorilla from the authors, with no explicit or implicit promise of reviewing it.

Check out the authors' website:

Follow them on twitter at @invisgorilla, and follow Dan Simons on twitter at @profsimons

More like this

The first time one of my professors showed us this, I was able to count the passes and see the gorilla on the same first viewing. What does that imply, if anything?

By O Pioneer (not verified) on 13 Aug 2010 #permalink

Doesn't really imply anything. Like any illusion (perceptual, cognitive, or otherwise) there will be some segment of the population who won't be "fooled" by it, the first time around.

Jason thanks for this review. I saw the book in my local B&N and for some reason I assumed it was a fictional book (perhaps due to the location of the book within the store) or a book about the study itself (which I already new about). Never took the time to actually pick the book up to read the synopsis, but I'll have to pick it up the next time Im in there. This is a topic that interests me as a psych major and as an interest in general.

I saw the second video in a presentation. I got the count right and neither realized the gorilla nor the color change. However, I wonder whether this could be due to selective attention. I simply was too busy following the path of the ball and therefore didn't pay attention to anything else in my visual field. As an educator I know that sometimes people just don't see, because their attention was not guided correctly. Do I get this wrong or am I one of those, you're referring to at the beginning of your last paragraph.

Martin: this is exactly the point. The interesting thing is in the original study, people were convinced that the tapes had been changed. How had they missed something so obvious? But the fact is when you are engaged in a task (like counting basketball passes), not everything in the visual field reaches conscious awareness.

The perceptual illusion is not seeing the gorilla (or the other changes, in the second video). The cognitive illusion is being sure that you would have noticed, if there *had* been a gorilla.

Hey, I saw the Gorilla too and have the 15 passes right. I even saw, every movement Gorilla did.

I saw the gorilla, and also noticed that there was a person missing but did not see them leave. I did notice all the gorilla's movements, but did not notice the curtain colour changing. My count was off by 1.