The Invisible Gorilla

Summary Written by Joel D Canfield
"We experience far less of our visual world than we think we do."

- The Invisible Gorilla, page 7

The Big Idea

Seeing Often Isn't

"When people devote their attention to a particular area or aspect of their visual world, they tend not to notice unexpected objects, even when those unexpected objects are salient, potentially important, and appear right where they are looking."- The Invisible Gorilla, pages 6–7

Chabris and Simons make it clear, they’re not speaking metaphorically. The research shows over and over that we can look right at something, something meaningful, important, and simply not see it.

Focus, as when counting the passes in the gorilla video, causes blindness to portions of the world we’re not focusing on. This is how the brain is designed. Expectations allow us to focus, to set goals, to go confidently in the direction of, if not dreams, at least the next stop.

“But for the human mind, expectations and goals are inextricably intertwined with the most basic processes of perception and are not readily extinguished. Expectations are based on our prior experiences of the world, and perception builds on that experience.”

Next time you disagree with someone’s account of a shared experience, ask yourself if the differences you think you remember are more salient than a chest-thumping gorilla on a basketball court. If not, what makes you think what either of you saw in the first place or remembers afterward is “the truth”?

That’s the greatest value in recognizing inattentional blindness: how we react when presented with evidence that two perfectly rational intelligent people saw the same thing very differently.

While it would be great to proactively combat inattentional blindness, there’s a reason we can’t: we’d lose our ability to focus.

Insight #1

Attention is a Zero-Sum Game

"For the human brain, attention is essentially a zero–sum game: if we pay more attention to one place, object, or event, we necessarily pay less attention to others."- The Invisible Gorilla, page 38

Many of us go through life believing our eyes and ears are recording the world around us like a 3D video, to be stored and played back at will later using the thing we call memory.

Physiologically, that’s not how it works. Our eyes are physically capable of taking in a certain amount of information, and no more. The connection from our eyes to our brain and the perceptive centers in the brain are capable of making sense of only a certain amount of information, and no more.

Trying to pay attention to more than we can is exactly like trying to fly by flapping your arms: your body doesn’t work that way.

Our ability to focus is vital to life. Without it, nothing around us would make sense. We see a loved one’s face in a crowd — but not the other 999 faces. We see the book we’re looking for on the shelf, but not the one on the shelf just above which we might also find interesting. The fact that you can ever find anything, from a golf ball to the next turn, is due to your ability to focus.

Inattentional blindness keeps us from seeing the unexpected. The events we miss, from gorillas in a basketball game to drivers coming the wrong way down a one-way street, are unexpected because they’re rare. Most of us go through life unaware of inattentional blindness simply because we rarely experience negative repercussions. When we’re in a fender-bender with the nut going the wrong way down the street, we don’t blame our zero-sum ability to focus, we blame the nut (and, I believe, rightly so.)

When we don’t notice continuity errors in a movie (Julia Roberts picks up a croissant, then she’s suddenly eating a pancake) or our significant others’ new hair style, it’s rarely life-threatening, which is why we’ve all managed to stumble through life this far.

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Insight #2


"The three biases underlying the illusion of cause — overzealous pattern detection mechanisms, the unjustified leap from correlation to causation, and the inherent appeal of chronological narratives."- The Invisible Gorilla, page 174

I cannot prove this story is true, but I want it to be true: a caller told the help desk at their company that when they hit the spacebar on their computer, the phone in the next cubicle rang — but only sometimes.

We are wired for narrative; that is, we’re not just storytellers, we’re story listeners. Story is part of our makeup. As a result, when we experience A, then B, then C, our brain tells us A caused B, which resulted in C.

A graph of ice cream consumption and drowning would show a neat correlation: as one goes up or down, the other does the same. You probably realize that ice cream doesn’t cause drowning. It’s not a huge leap to the idea that hot weather leads to more ice cream and more swimming. More swimming, unfortunately, leads to more drownings.

There’s a correlation between ice cream consumption and drowning, but certainly not causation.

Sometimes the random chance or third-party causation isn’t so obvious. The complete lack of any causative link between immunizations and autism has been documented repeatedly, but the powerful parental experience of one following the other overrides, overwhelms, any logical considerations.

Just as our brain’s facial recognition systems can cause us to see faces in the whorls of a tree, a pattern of dots, or the browning on a grilled cheese sandwich, our innate ability (and desire) for story, for sequential narrative experience, leads us to infer cause and effect where there’s nothing more than two unrelated events connected only by the fact that we noted them both.

Without realizing it, we go through life like Homer Simpson, hoping to buy Lisa’s rock to keep the tigers away. (Google it.) Just because we don’t see bears does not mean the bear patrol is working.

We survive just fine with our illusions. We’re rarely seriously damaged by inattentional blindness, by a faulty memory, by too much trust in the confidence of others, or by leaping to conclusions about cause and effect.

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