The Invisible Gorilla: And Other Ways Our Intuitions Deceive Us (6 page)

Fellow staffers at the
Washington Post
magazine apparently expected a different result. According to Weingarten’s story, they had been worried that the performance might cause a riot:

After the stunt was over, Weingarten asked famous conductor Leonard Slatkin, who directs the National Symphony Orchestra, to predict how a professional performer would do as a subway artist. Slatkin was convinced a crowd would gather: “Maybe 75 to 100 will stop and spend some time listening.” During the actual performance, less than one-tenth that number stopped, and the National Guard did not mobilize.

Weingarten, his editors, Slatkin, and perhaps the Pulitzer committee members fell prey to the illusion of attention. Even Bell, when he saw the video of his performance, was “surprised at the number of people who don’t pay attention at all, as if I’m invisible. Because, you know what? I’m makin’ a lot of noise!”
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Now that you’ve read about invisible gorillas, neglected fishing vessels, and unseen motorcycles, you can likely guess one reason why Bell went unrecognized for the great musician he is. People weren’t looking (or listening) for a virtuoso violinist. They were trying to get to work. The one person interviewed for the story who correctly understood the minimal response to Bell was Edna Souza, who shines shoes in the area and finds buskers distracting. She wasn’t surprised that people would rush by without listening: “People
walk up the escalator, they look straight ahead. Mind your own business, eyes forward.”

Under the conditions Weingarten established, commuters were already engaged in the distracting task of rushing to get to work, making them unlikely to notice Bell at all, let alone focus enough attention on his playing to distinguish him from a run-of-the-mill street musician. And that is the key. Weingarten’s choice of time and location for the stunt nearly guaranteed that nobody would devote much attention to the quality of Bell’s music. Weingarten is concerned that “if we can’t take the time out of our lives to stay a moment and listen to one of the best musicians on Earth play some of the best music ever written; if the surge of modern life so overpowers us that we are deaf and blind to something like that—then what else are we missing?” Probably a lot, but this stunt provides no evidence for a lack of aesthetic appreciation. A more plausible explanation is that when people are focusing attention (visual and auditory) on one task—getting to work—they are unlikely to notice something unexpected—a brilliant violinist along the way.

If we were designing an experiment to test whether or not Washingtonians are willing to stop and appreciate beauty, we would first pick a time and location where an average street performer would attract an average number of listeners. We would then randomly place either a typical street performer or Joshua Bell there on several different days to see who earned more money. In other words, to show that people don’t appreciate beautiful music, you first have to show that at least some people are listening to it and then show that they reward it no more than they do average music. Weingarten wouldn’t have won a Pulitzer had he stationed Bell next to a jackhammer. Under those conditions, nobody would be surprised by the lack of attention to the musician—the deafening sound would have drowned out the violin. Placing Bell next to a subway station escalator during rush hour had the same effect, but for a different reason. People physically could have heard Bell playing, but because their attention was diverted by their morning commute, they suffered from inattentional deafness.

Other factors worked against Bell as well—he was performing
relatively unfamiliar classical pieces rather than music that most commuters would know. If Bell had played
The Four Seasons
or other better-known classical pieces, he might have done better. By doing so, a far less talented musician could have taken in more money than Bell did. When Dan lived in Boston, he occasionally walked from downtown to the North End to get Italian food. At least half a dozen times, he walked past an accordion player who stationed himself at one end of an enclosed walkway that ran past a highway—a perfect place to attract listeners with time on their hands, walking to restaurants that they’d probably have to wait to get into anyhow. For street artists, like for real estate, location is everything. The accordionist played with gusto, showing an emotional attachment to his instrument and his art. Yet, Dan only ever heard him play one song: the theme from
The Godfather
. He played it when Dan walked to dinner and when Dan walked back from dinner, every time Dan made that trip. Either he spotted Dan before he was within earshot and instantly started playing the
Godfather
theme as some odd sort of joke or warning (Dan has yet to wake up with a bloody horse’s head at his feet), or he simply recognized the appeal to his audience of playing what may be the most familiar accordion piece. Our bet is that he did quite well. Had Bell performed on a Saturday afternoon, he likely would have attracted more listeners. Had he played shorter pieces on a subway platform rather than extended pieces next to the exit escalator, he might have attracted more listeners who had to wait for trains. And had he played the theme from
The Godfather
on his three-hundred-year-old violin, who knows.

Chris once demonstrated the gorilla experiment to students in a seminar he was teaching. One of them told him the next week that she’d shown the video to her family, and that her parents had both missed the gorilla but her older sister had seen it. The sister then proceeded to crow about her triumph in this gorilla-noticing competition, claiming that it showed how smart she was. Dan regularly receives e-mails from
people he’s never met asking why they missed the gorilla but their children saw it, or whether girls always notice but boys never do. A hedge fund manager found out about our study and had the people in her office do it. She tracked Chris down through a chain of acquaintances and interrogated him about the differences between people who notice the gorilla and people who don’t.

Many people who have experienced the gorilla experiment see it as a sort of intelligence or ability test. The effect is so striking—and the balance so even between the number who notice and the number who don’t—that people often assume that some important aspect of your personality determines whether or not you notice the gorilla. When Dan was working with
Dateline NBC
to create demonstrations, the show’s producers speculated that employees in detail-oriented occupations would be more likely to notice the gorilla, and they asked most of their “subjects” what their jobs were. They assumed that how you perform on the task depends on what kind of person you are: a “noticer” or a “misser.” This is the question of
individual differences
. If we could figure out whether some people consistently notice the gorilla and other unexpected events in laboratory tasks, then we could figure out whether they are immune to inattentional blindness more generally, and potentially train the missers to become noticers.

Despite the intuitive appeal of the gorilla video as a Rosetta stone for personality types, there is almost no evidence that individual differences in attention or other abilities affect inattentional blindness. In theory, people could differ in the total attentional resources they have available, and those with more resources (perhaps those with higher IQs) might have enough “left over” after allocating some to the primary task to be better at detecting unexpected objects. One argument against this possibility, though, is the consistency in the pattern of results we obtain with the gorilla demonstration. We conducted the original experiment on Harvard undergraduates—a fairly elite group—but the experiment works just as well at less prestigious institutions and with subjects who aren’t students. In all cases, about half of the subjects see the gorilla and half don’t. According to an online survey by Nokia,
60 percent of women
and
men think that women are better at multitasking. If you agree, you might also think that women would be more likely to notice the gorilla. Unfortunately, there is little experimental evidence to support the popular belief about multitasking, and we haven’t found any evidence that men are more prone than women to miss the gorilla. In fact, the main conclusion from studies of multitasking is that virtually nobody does it well: As a rule, it is more efficient to do tasks one at a time rather than simultaneously.
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It’s still possible—even reasonable—to suspect that people differ in their ability to focus attention on a primary task, but that this ability isn’t related to general intelligence or educational achievement. If individual differences in the ability to focus attention lead to differences in noticing unexpected objects, then people for whom the counting task is easier should be more likely to notice the gorilla—they are devoting fewer resources to the counting task and have more left over.

Dan and his graduate student Melinda Jensen recently conducted an experiment to test exactly this hypothesis. They first measured how well people could do a computer-based tracking task like the one we used in the “red gorilla” experiment and then looked to see whether those who performed the task well were more likely to notice an unexpected object. They weren’t. Apparently, whether you detect unexpected objects and events doesn’t depend on your capacity for attention. Consistent with this conclusion, Dan and sports scientist Daniel Memmert, the researcher who tracked children’s eye movements while they watched the gorilla video, found that who noticed and who missed an unexpected object was unrelated to several basic measures of attention capacity. These findings have an important practical implication: Training people to improve their attention abilities may do nothing to help them detect unexpected objects. If an object is truly unexpected, people are unlikely to notice it no matter how good (or bad) they are at focusing attention.

As far as we can tell, there are no such people as “noticers” and “missers”—at least, no people who consistently notice or consistently miss unexpected events in a variety of contexts and situations. There is one way, however, to predict how likely a person is to see the unexpected.
But it is not a simple trait of the individual or a quality of the event; it is the combination of a fact about the individual and a fact about the situation in which the unexpected event occurs. Only seven people out of more than one thousand stopped to listen to Joshua Bell playing in the L’Enfant Plaza subway station. One had been to a concert Bell had given just three weeks earlier. Two of the remaining six were musicians themselves. Their expertise helped them recognize his skill—and the pieces he was playing—through the din. One, George Tindley, worked in a nearby Au Bon Pain restaurant. “You could tell in one second that this guy was good, that he was clearly a professional,” he told Weingarten. The other, John Picarello, said, “This was a superb violinist. I’ve never heard anyone of that caliber. He was technically proficient, with very good phrasing. He had a good fiddle, too, with a big, lush sound.”

Experiments support this observation. Experienced basketball players are more likely to notice the gorilla in the original basketball-passing video than are novice basketball players. In contrast, team handball players are no more likely to notice unexpected objects even though they are experts in a team sport that places demands on attention comparable to those of basketball.
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Expertise helps you notice unexpected events, but only when the event happens in the context of your expertise. Put experts in a situation where they have no special skill, and they are ordinary novices, taxing their attention just to keep up with the primary task. And no matter what the situation, experts are not immune to the illusory belief that people notice far more than they do. Gene Weingarten described John Picarello’s behavior as he watched Bell play: “On the video, you can see Picarello look around him now and then, almost bewildered. ‘Yeah, other people just were not getting it. It just wasn’t registering. That was baffling to me.’”

Even within their field of specialty, experts are not immune to inattentional blindness or the illusion of attention. Radiologists are medical
specialists responsible for reading x-rays, CT scans, MRIs, and other images in order to detect and diagnose tumors and other abnormalities. Radiologists perform this visual detection task under controlled conditions every day of their careers. In the United States, their training involves four years of medical school, followed by up to five years in residency at a teaching hospital. Those who specialize in specific body systems spend another year or two in fellowship training. In total, they often have more than ten years of post-undergraduate training, followed by on-the-job experience in studying dozens of films each day. Despite their extensive training, radiologists can still miss subtle problems when they “read” medical images.

Consider a recent case described by Frank Zwemer and his colleagues at the University of Rochester School of Medicine.
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An ambulance brought a woman in her forties to the emergency room with severe vaginal bleeding. Doctors attempted to insert an intravenous line in a peripheral vein, but failed, so they instead inserted a central line via a catheter in the femoral vein, the largest vein in the groin. Getting the line in correctly requires also inserting a guidewire, which is removed once the line is in place.

The line was introduced successfully, but due to an oversight, the physician neglected to remove the guidewire.
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To address her blood loss, the patient was given transfusions, but she then developed difficulty breathing due to pulmonary edema (a swelling or fluid buildup in the lungs). She was intubated for respiratory support, and a chest x-ray was taken to confirm the diagnosis and make sure that the breathing tube was placed correctly. The ER doctor and the attending radiologist agreed on the diagnosis, but neither of them noticed the guidewire. The patient went next to the intensive care unit for several days of treatment, and after she improved she went to a standard unit. There she developed shortness of breath, which was caused by pulmonary embolism—a blood clot in her lung. During this time she received two more x-rays, as well as an echocardiogram and a CT scan. Only on the fifth day of her stay in the hospital did a physician happen to notice and remove the guidewire while performing a procedure to correct
the pulmonary embolism. The patient then made a full recovery. (It was determined later that the guidewire probably didn’t cause the embolism because it was constructed of so-called nonthrombogenic material specifically intended not to promote blood clotting.)