The Invisible Gorilla: And Other Ways Our Intuitions Deceive Us

by Christopher Chabris

  A commenter on the Post’s website responded to the fact-checking article: “There are only three ways to explain Clinton’s story here: (a) she is a bald-faced liar; (b) her perception of reality is utterly skewed; or (c) her memory is utterly demented.” Political commentator Peggy Noonan wrote in the Wall Street Journal that “we have to hope they were lies, because if they weren’t, if she thought what she was saying was true, we are in worse trouble than we thought…. It was as if she’d watched the movie Wag the Dog, with its fake footage of a terrified refugee woman running frantically from mortar fire, and found it not a cautionary tale about manipulation and politics, but an inspiration.” A cover of the New Republic depicted a bug-eyed Clinton hearing “voices in her head” and ranting that she offered to sacrifice her own life to protect her traveling companions in Bosnia (“And I said to Sinbad, ‘Leave me, save yourself!’”). This is the typical response of the human mind to another person’s false memory, especially an arguably self-serving memory like Clinton’s grace-under-fire brush with death. Even Bill Clinton later proffered commonsense excuses for his wife’s memory lapse, claiming (incorrectly) that she made the comments late at night and pointing out (correctly but perhaps unhelpfully) that she was sixty years old.

  An entirely plausible alternative explanation for Clinton’s fictitious snipers is that, like all fallible human minds, hers automatically and unconsciously reconstructed the landing in Tuzla to be consistent with the image of herself that she was convinced was accurate. Like Neil Reed’s memory of being reprimanded by Bobby Knight, Clinton’s memory of arriving in Bosnia was systematically distorted to become consistent with her internalized, personal narrative. Like Reed, and the students whose flashbulb memories of the Challenger explosion proved inaccurate, Clinton could easily have had full confidence in the accuracy of her memory. And, as in Reed’s case, videos revealed the truth. Hillary Clinton’s distorted memory contributed to her loss of the presidential nomination by helping to revivify the popular impression, fair or not, that she would say anything to get elected (an impression that was compounded by her initial refusal to acknowledge the error after the videos surfaced).43

  Is it possible to distinguish calculated deception from accidental distortion? We noted earlier that the illusion of memory does not apply equally to all memories. We are more aware of the limits on our ability to remember arbitrary facts and details, and we do not expect others to remember such details. We do not expect people to be able to remember random fifteen-digit numbers, although even for digit memory, people do overestimate their own ability to remember. It turns out that more than 40 percent of respondents to a survey thought they could remember ten random digits, even though less than 1 percent of people can actually do this when they are tested.44 However, the illusion of memory is more powerful when we remember personally relevant information or experiences. The critical factor driving the illusion seems to be the extent to which a memory triggers a strong recollective experience. In other words, if you recall how you experienced and learned something rather than merely what you experienced and learned, you are far more likely to trust the veracity of your memory. Just as the vividness of our visual perception makes us think we are paying attention to more than we are, our experience of fluent, vivid recollection fuels the illusion of memory. When we recall a set of arbitrary digits or facts, we do not have a strong recollective experience. When we recall how we learned about the 9/11 attacks, we do. That is why Hillary Clinton and Neil Reed held firm to what they remembered—they had distinct and powerful recollections of what happened, and the vividness of their memories led them to believe them more strongly.45

  The vividness of our recollections is tied to how they affect us emotionally. For most people, lists of numbers do not inspire fear or sadness, but thoughts of 9/11 do. And these emotions affect how we think we remember, even if they do not affect how much we actually remember. Subjects in an experiment were asked to view either emotionally neutral photographs, such as a farm scene, or strongly arousing and negative images, such as a gun pointed right at the camera.46 Later, when asked to decide whether they had seen these images before, they had stronger recollective experiences for the emotional pictures than the neutral ones. Emotional memories, like the ones we have for 9/11, are more likely to induce strong, vivid recall—regardless of whether they are accurate. Beware of memories accompanied by strong emotions and vivid details—they are just as likely to be wrong as mundane memories, but you’re far less likely to realize it.

  Unfortunately, people regularly use vividness and emotionality as an indicator of accuracy; they use these cues to assess how confident they are in a memory. Critically, people also judge the accuracy of another person’s memory based on how much confidence that person expresses in the memory. As we will see in the next chapter, the tendency to assume that confidently recalled memories are accurate ones illustrates another cognitive illusion: the illusion of confidence.

  what smart chess players and stupid criminals have in common

  ONE SUMMER DAY when he was in graduate school, Chris woke up with a headache. This wasn’t unusual—he has always been prone to headaches. Later that day the aches spread to the rest of his body, and he began to feel exhausted and apathetic. It was a chore to get up from bed, walk into the living room of his apartment, sit down, and turn on the TV. His whole body hurt when he tried to stand up. Simple tasks like taking a shower left him breathless. The symptoms suggested a bad flu, but strangely he had no respiratory symptoms, and July is not exactly the height of flu season. After feeling awful for a few days, Chris went to Harvard’s health service. The nurse who saw him concluded that it probably was a virus and told him to rest and stay hydrated.

  The next day, a Sunday, his symptoms unchanged, Chris took one of those enervating showers. Moving slowly to conserve energy, he turned to let the water hit the back of his legs, and just when it did he felt a sharp pain. Twisting his neck and looking down, he saw a huge red rash that looked like a sunburst, right in the middle of his left calf. It was much larger than any mosquito bite he’d ever seen. Armed with a new symptom, he went into the after-hours care department and proudly displayed the rash. The doctor on duty asked Chris whether he’d been bitten by a tick recently. At first Chris was inclined to say no, since he’d never even seen a tick in the city of Cambridge, Massachusetts. But then he remembered that he’d visited his parents in Armonk, a suburb of New York City, a couple of weeks earlier, and had spent time with his mother in her vegetable garden. There were plenty of ticks there. The doctor showed Chris a picture from a medical book that illustrated the characteristic skin rash produced from infection by Borrelia burgdorferi, the tick-borne bacteria that cause Lyme disease. It looked exactly like Chris’s calf.1

  If Lyme disease isn’t diagnosed early, it becomes more difficult to treat and has the potential to cause chronic disability. After the doctor explained the diagnosis, she excused herself from the room. She returned moments later with another book, in which she looked up the treatment for acute Lyme disease. She wrote a prescription for twenty-one days of the antibiotic doxycycline and handed it to Chris.

  Chris was a little unnerved by this experience. First, the diagnosis itself seemed ominous. But more unsettling was the doctor’s open consultation of reference books during the session. Chris had never seen a doctor do this before, and this one did it twice. Did she know what she was doing? In the northeastern United States, where Lyme disease is prevalent, how could an urgent-care doctor not be familiar with its diagnosis and treatment? Chris went straight to the drugstore to fill the prescription, but he couldn’t help feeling uneasy about the doctor’s uncertainty.

  If you encountered a doctor who had to look up the diagnostic criteria and recommended treatment for your condition, wouldn’t you wonder too? To do so would only be natural: We all tend to think of a confident doctor as a competent one and an uncertain doctor as a potential malpractice suit. We treat confidence as an honest signal of a person�
�s professional skill, accurate memory, or expert knowledge. But as you’ll see in this chapter, the confidence that people project, whether they are diagnosing a patient, making decisions about foreign policy, or testifying in court, is all too often an illusion.

  Where Everyone Thinks They Are Underrated

  To understand this illusion of confidence, we will begin in an unlikely place: the ballroom of the Adams Mark Hotel in Philadelphia, longtime site of the aptly named World Open, one of the largest annual open chess tournaments in the world. Anyone who pays the entry fee, from novice to grandmaster, can play. In 2008, more than fourteen hundred players competed for over $300,000 in prize money. The scene is not necessarily what you’d expect. For one thing, silence does not reign; there is a constant patter of chess pieces clicking against other pieces and buttons on chess clocks being slapped as players make their moves. Outside the playing rooms, it’s even noisier. Players chatter about the games they just finished, the games they’re about to play, and even about the games they’re playing at that moment. (The rules permit general conversation about your game, as long as you don’t solicit or receive advice from anyone.) The players themselves aren’t all like the geeky, dateless high school chess team members you remember. Nor are they all bearded, pensive old men. Some could definitely use a shower or a makeover, but most are normal-looking children, parents, lawyers, doctors, engineers; there are also professional chess players, many from foreign countries. One stereotype does hold true, though: There is a distinct absence of women. Fewer than 5 percent of tournament chess players are female.

  The strangest thing about the players in this tournament—indeed, about the players in every chess tournament—is that they know precisely how good they are at chess compared with the other players. This is not true of most activities in life, or even of most competitive endeavors. There is no master ranking scale to tell you how you compare in skill with other drivers, business managers, teachers, or parents. Even professions like law and medicine have no clear way of determining who is best. This lack of a clear measure of ability makes it easy to get an inflated sense of your own skill. But chess has a mathematically objective, public rating system that provides up-to-date, accurate, and precise numerical information about a player’s “strength” (chess jargon for ability) relative to other players. All tournament players know that if you win a tournament game, your rating goes up, and if you lose a game, your rating goes down. Battling a higher-rated player to a draw also raises your rating, while drawing with a lower-rated player reduces it. Ratings are public knowledge and are printed next to each player’s name on tournament scoreboards; many players ask their opponent “What’s your rating?” before beginning a game. Ratings are valued so highly that chess players will remember their opponents better by their ratings than by their names or faces. “I beat a 1726” or “I lost to a 1455” are not uncommon things to hear in the hallway outside the playing room.

  In July 1998, the average U.S. Chess Federation rating of the 27,562 people who’d played at least twenty tournament games was 1337. Masters are players rated 2200 or higher. Chris achieved this milestone when he was in college. Dan had a rating just under 1800 in high school but hasn’t played competitively since then. Comparing two players’ ratings gives the odds that one will defeat the other. Ratings are set and adjusted so that over a long series of games, a player rated two hundred points higher than his opponent should score about 75 percent of the points (wins count as one point, draws count as half a point). A player rated four hundred points higher than his or her opponent is expected to win almost every game.

  Despite playing hundreds of tournament games in high school and being well above average for a tournament player, Dan never beat a master-level player, and he would stand effectively no chance of beating Chris in a tournament game. Similarly, Chris has defeated only one grandmaster in tournament play, despite once being ranked among the top 2 percent of players nationally. The differences in skill between these levels are just too large. If you consistently beat a player with the same rating as yours, then your rating will go up and theirs will go down so that the forecasts predict that you will beat them in the future. Unlike the rankings published for most sports, the chess rating system is extremely accurate; for practical purposes, your rating is a nearly perfect indicator of your ability. Armed with knowledge of their own ratings, and the workings of the rating system, players ought to be exquisitely aware of how competent they are. But what do they actually think about their own abilities?

  Together with our friend Dan Benjamin, who was then an undergraduate student at Harvard and is now an economics professor at Cornell University, we ran an experiment at the World Open in Philadelphia and at another tournament, the U.S. Amateur Team Championship in Parsippany, New Jersey. As players walked by on their way to or from their games we asked them to fill out a short questionnaire. We posed two simple questions: “What is your most recent official chess rating?” and “What do you think your rating should be to reflect your true current strength?”2

  As expected, the players knew their ratings: Half reported their ratings exactly, and most of the rest were off by only a few points. Since the players know what they are rated, they ought to be able to correctly answer the second question about what they should be rated. The correct answer is their current rating, because the rating system’s design ensures that ratings are an accurate measure of skill. But only 21 percent of the players in our experiment actually said their current rating reflected their true strength. About 4 percent thought they were overrated, and the other 75 percent believed they were underrated. The magnitude of their overconfidence in their own playing ability was stunning: On average, these competitive chess players thought they were ninety-nine points underrated, which means they believed that they would win a match against another player with the exact same rating as their own by a two-to-one margin—a crushing victory. Of course, in reality the most likely outcome of a match against a player with the same rating as their own would be a tie.

  What explains this extreme overconfidence in the face of concrete evidence for their actual skills? Not a lack of familiarity with chess: These players had played the game for an average of twenty years. Not a lack of feedback about their competitive skill levels: They had been playing in rated tournaments for thirteen years, and their average rating was 1751, well above the average player’s. Not being out of touch with their own skill level (from being out of practice): Over half had played at least one other tournament within the two months before we surveyed them.

  Perhaps the players interpreted our question slightly differently than we had intended. Maybe they were predicting what their ratings would be once the system caught up to their true strength. Because ratings are adjusted only after tournaments, and the updated ratings sometimes take a month or two to be published, it is possible for rapidly improving players to be systematically underrated in the official lists, because they are improving at a rate too fast for their ratings to keep up. We checked our subjects’ ratings a year later, and the players were rated almost exactly as they had been when we first did the experiment: one hundred points lower than their own estimates of their skill. In fact, even after five years, they still hadn’t reached the levels they had estimated as their actual strength. The overconfidence that players displayed cannot be explained by a reasonable expectation of future improvement.3 Our tournament chess players, despite their long and intimate experience with competitive chess ratings, overestimated their abilities. They suffered from our third everyday illusion: the illusion of confidence.

  The illusion of confidence has two distinct but related aspects. First, as with the chess players, it causes us to overestimate our own qualities, especially our abilities relative to other people. Second, as Chris experienced in the doctor’s office, it causes us to interpret the confidence—or lack thereof—that other people express as a valid signal of their own abilities, of the extent of their knowledge, and of the accuracy of their
memories. This wouldn’t be a problem if confidence in fact had a close relationship with these things, but the reality is that confidence and ability can diverge so far that relying on the former becomes a gigantic mental trap, with potentially disastrous consequences. Thinking you’re better at chess than you really are is only the beginning.

  “Unskilled and Unaware of It”

  Charles Darwin observed that “ignorance more frequently begets confidence than does knowledge.”4 In fact, those who are the least skilled are the most likely to think better of themselves than they should—they disproportionately experience the illusion of confidence. Some of the most striking examples of this principle come from criminals, an idea captured in Woody Allen’s first feature film, Take the Money and Run.5 Allen stars as Virgil Starkwell, a boy raised in difficult circumstances who turns to a life of crime as a teenager. But Virgil never manages to achieve success in his profession. As a child he tries to steal gumballs but gets his hand stuck and has to run down the street carrying the entire machine. As an adult he tries to rob a bank, but the tellers can’t read his holdup note and the police arrive before he can explain it to them. He tries to break out of jail by carving a gun out of soap and coating it with black shoe polish, but as he leaves, it pours rain and the guards notice suds frothing from his weapon.