The Invisible Gorilla: And Other Ways Our Intuitions Deceive Us

by Christopher Chabris

  The Real Way to Unlock Your Potential

  Please don’t get us wrong. We’re not trying to argue that there is literally no potential for increasing our mental abilities. Our intellectual capacities are never frozen in place. We all have tremendous potential to learn new skills and to improve our abilities. Indeed, neuroscience research is showing that the plasticity of the adult brain—its ability to change in structure in response to training, injury, and other events—is much greater than previously believed. The illusion is that it is easy to unlock this potential, that it can be discovered all at once, or that it can be released with minimal effort. The potential is there, in everyone, to acquire extraordinary mental abilities. Most people, without any training, can remember a list of about seven numbers after hearing it only once. Yet one college student trained himself to be able to remember up to seventy-nine digits.55 His feat was extraordinary, revealing a latent potential for exceptional digit memory, but it took hundreds of hours of practice and training. In principle, most people have the same potential ability, and could do the same thing with enough practice.

  Genius is not born fully formed—it takes years to develop, and it follows a predictable trajectory. Mozart’s early compositions were not masterpieces, and Bobby Fischer made plenty of mistakes when he was learning the game of chess. Both likely possessed exceptional talent to develop, but they did not become great without training and practice. And their greatness was limited to the domains they trained in. Training your memory for digits will not help you remember names. However, expertise in a domain does improve many other abilities within that domain that were not specifically trained.

  A series of classic experiments conducted by the pioneering cognitive psychologists Adriaan de Groot, William Chase, and Herbert Simon demonstrated that chess masters can remember far more than seven items when the items tap into their expertise.56 We repeated their studies ourselves by testing Chris’s friend Patrick Wolff, a grandmaster who had won the U.S. championship twice. We brought Patrick into the lab and showed him a diagram of a chess position from an obscure master game for just five seconds. We then gave him an empty chessboard and a set of pieces and asked him to re-create the position from memory. Remarkably, he could reconstruct the position with nearly 100 percent accuracy even when it contained twenty-five or thirty pieces, far more than the typical seven-item limit for short-term memory.

  After watching him perform this feat a few times, we asked him to explain how he did it. He first pointed out that the training of a chess grandmaster doesn’t include practice in setting up chess positions after seeing them for just a few seconds. He said that he was able to quickly make sense of the positions and to combine pieces into groups based on the relationships among them. In essence, by recognizing familiar patterns, he stuffed not one but several pieces into each of his memory slots. As he became an expert in chess, he developed other skills that help in playing chess well—mental imagery, spatial reasoning, visual memory—all of which contributed to his ability to do this memory task better than other people. However, being an expert in chess did not make him an imagery, reasoning, or memory expert in general. In fact, when the chess positions we showed him had the same number of pieces arranged on the board randomly, his memory was no better than that of a beginner, because his chess expertise and database of patterns were of little help. The same principle applies to the student who stretched his memory span to seventy-nine digits—his new memory capacity was specific to combinations of numbers, so even after several months of training with numbers, he still had a span of only six items when tested with letters.57 In other words, he trained his potential ability to remember numbers, but that training did not transfer to any other skills.

  Chess grandmasters can apply their expertise to perform a wide variety of chess tasks extremely well, even if they have never carried out those tasks before. One of the most dramatic examples is blindfold chess. Top players can play an entire game “blindfolded,” without ever looking at the board—they are told (in chess notation) what moves their opponents have made, and they announce the moves they would like to make in reply. Grandmaster-level players can play two or more blindfold games simultaneously, at a high level of skill, even if they’ve never tried this before. The exceptional chess memory and imagery abilities needed to perform this feat accrue more or less automatically as players become experts.

  Working with Eliot Hearst (another psychology professor who is also a chess master), Chris conducted a study to measure how much worse chess grandmasters play when they can’t see the board and pieces.58 You might think that they’d make more errors because of the additional memory load of remembering where every piece is. To find out whether this supposition is true, Chris took advantage of a unique chess tournament that has taken place in Monaco every year since 1992. In the tournament, twelve of the world’s top players, including many world championship contenders, play each other twice: once under normal conditions, and once under blindfold conditions. Since the same players are involved in the normal and blindfold games, any difference in the number of errors must be due to the conditions, not the competitors.

  In total, from 1993 to 1998 there were about four hundred regular games and four hundred blindfold games played in the tournament, with each lasting an average of forty-five moves by each player. Chris used a chess-playing program called Fritz, which was recognized as one of the best software chess players in the world, to find all the serious mistakes the humans made. Fritz undoubtedly missed some of the most subtle errors, but larger blunders and significant mistakes were easy for it to catch.

  Under normal playing conditions, the grandmasters made an average of two mistakes for every three games. These were major blunders, ones that could have—and often did—cost them a game against top-level opposition. The surprise, though, was that the rate of errors in blindfold chess was virtually the same. The grandmasters had trained their potential so well that they could perform their art without even looking at its elements (look, Ma, no board or pieces!). For those interested in unlocking their potential, that’s good news, of course. The bad news is that they didn’t become chess grandmasters by just listening to the right music or reading the right self-help books. They did it by concentrated study and practice over a period of at least ten years. The brain’s potential is vast, and you can indeed tap into it, but it takes time and effort.

  Get Your Head in the Game

  Practicing games like chess will enhance your ability to do chess-related tasks, but the transfer is relatively limited. Advocates for adding chess to school curricula argue that “chess makes you smarter,” but there is no solid evidence for this claim from large, properly controlled experiments.59 Is there any evidence for broad transfer of skill to tasks and domains other than the one you practice?

  Cognitive psychologists were jarred into rethinking the limits of transfer by a striking set of experiments published in 2003 by Shawn Green and Daphne Bavelier of the University of Rochester.60 The central conclusion of these studies was that playing video games can improve your ability on a variety of basic cognitive tasks that are, at least on their surface, unrelated to the video games you play. Their first four experiments showed that expert video-game players, defined as people who had played at least four hours per week for the past six months, outperformed video-game novices on tests of some attention and perception abilities. Although this sort of comparison is interesting and provocative, as we discussed in Chapter 5, an association alone does not support a causal inference. It is quite possible that only people with superior abilities in attention and perception become video-game addicts, or that other differences between the experts and novices might contribute to the differences in cognitive performance. Dan’s colleague Walter Boot, a psychology professor at Florida State University, suggests one such factor: “People who are able to handle college while also spending a lot of time playing video games are different from people who need to spend more of their time studying.”61 The onl
y way to avoid such confounding factors and determine for sure whether playing video games improves attention and perception is to give novice players video-game training and then see whether their cognitive abilities have improved.

  Green and Bavelier did exactly that in their final experiment. They recruited novice video-game players, defined as people who had spent little or no time playing video games in the past six months, and randomly assigned these subjects to one of two groups. One group spent one hour a day for ten days playing Medal of Honor, a fast-paced “first-person shooter” game in which players view and monitor their surroundings as if they were looking through the eyes of their character in the game’s world. A second group played the two-dimensional puzzle game Tetris for the same amount of time. Before this practice, each completed a battery of basic cognition, perception, and attention tasks, and after training, they repeated the same battery of tasks. For example, in one of the tasks, known as Useful Field of View, a simple object appeared for just a fraction of a second right where the subject was looking, and subjects made a judgment about it (such as whether it was a car or a truck). At the same moment, another object appeared at some distance from where they were looking, and they had to determine where the peripheral object had appeared. The task measures how well people can focus attention on a central object while still devoting some attention to their periphery.

  Green and Bavelier hypothesized that action video games would lead to better performance on this task because people have to focus on a wide field of view to do well in the games. In contrast, Tetris should not be of as much benefit because it doesn’t require players to distribute their attention as broadly. Their results confirmed their prediction: Subjects who practiced Medal of Honor showed dramatic improvement on a number of attention and perception tasks, but the Tetris group showed no improvement at all. Following training on Medal of Honor, subjects were more than twice as accurate in the field-of-view task as they had been before training. Before training, they correctly reported the location of about 25 percent of the peripheral targets, but after training they got more than 50 percent right.

  This finding was so surprising, and led to a publication in Nature, because it seemed to break down a wall between two ways that practice can improve our mental abilities. Suppose you work hard at becoming an expert Sudoku solver, spending all your free time doing nothing but solving Sudoku puzzles. You will, of course, get faster and more accurate at solving Sudoku. Moreover, you might find that your ability to solve KenKen puzzles—a new variant of Sudoku—also improves somewhat, even though you had not done a single one during the time you practiced Sudoku. Your improved performance on KenKen would be an example of “narrow transfer,” where improvement on one mental skill transfers to other highly similar skills. It would be more surprising to find that practicing Sudoku improved your ability to calculate tips in your head, prepare your income taxes, or remember telephone numbers. Improvements on those skills would demonstrate “broad transfer,” because they have little surface-level similarity to Sudoku. Playing Medal of Honor to get better at finding targets in a similar first-person-shooter video game would be an example of narrow transfer. Playing Medal of Honor to improve your ability to pay attention to your surroundings while driving your car is like solving Sudoku to get better at remembering telephone numbers. It’s an example of broad transfer, which is valuable because it improves aspects of cognition that weren’t specifically trained. Moreover, in this case, a different skill was improved by doing something fun and engaging. We’ll bet that you’re more likely to follow the adage “practice makes perfect” if the “practice” consists entirely of playing video games.

  Green and Bavelier’s experiment suggests that video-game training might actually enable people to release some untapped potential for broader skills without having to spend effort practicing those particular skills. It’s far from obvious why passively listening to ten minutes of Mozart should change a cognitive ability (spatial reasoning) that has little or nothing to do with music or even hearing. But video games do require players to actively use a variety of cognitive skills, and it’s not implausible that ten hours of training on a game that requires attention to a wide visual field could improve performance on a task that requires subjects to focus across a wide display, even though the game and the task are different in many other respects.

  Perhaps the most astonishing aspect of this experiment was that it required only ten hours of training. Think about the implications of this: We all spend much of our lives focusing on our environment from a first-person perspective, making rapid decisions, and acting on them. Daily tasks like driving require us to focus on a wide visual field—you need to focus both on the road in front of you and on the side streets. And you most likely have driven for much more than ten hours in the past six months. Even if you haven’t, you likely have done other things that require similar skills—playing any sport, or even walking down a crowded city street, requires similar rapid decisions and awareness of your surroundings. Why, then, should an additional ten hours of playing one video game have such a large effect on basic cognitive skills?

  One possible answer to this question is that playing video games does not actually produce dramatic improvements on largely unrelated tasks. As was the case with the Mozart effect, Green and Bavelier’s initial study could turn out to be an outlier—subsequent studies may show that video-game training is not as potent as originally thought. But it is also possible that there really is something about playing a first-person action video game that does release untapped potential with minimal effort. Video games can be more engaging and intense than many other activities that draw on the same cognitive abilities, so they could conceivably provide more productive and efficient training that extends beyond the game itself.

  More recently, Bavelier and her colleagues have used much more extensive training, often thirty to fifty hours, to find further cognitive benefits of video games. These studies have shown transfer to several different basic perceptual abilities. One study found that video-game training improved contrast sensitivity, which is essentially the ability to detect a shape that is similar in brightness to the background, like a darkly clad person walking along a poorly lit sidewalk.62 Another showed that action video-game training improved the ability to identify letters placed close together in the periphery of the visual field, essentially increasing the spatial resolution of attention.63 Given how basic and fundamental these skills are to all aspects of perception, these findings are even more surprising than the original field-of-view result.64 Metaphorically, these findings suggest that practicing video games is akin to putting on your glasses—it improves all aspects of visual perception. For example, increased contrast sensitivity should make driving at night easier. Even though these followup studies involved substantially more training, they showed broad transfer to abilities that could affect many real-world skills. That said, none of these articles have reported on transfer to performance on real-world tasks, and given the lack of any direct evidence, the authors are appropriately careful not to claim any impact beyond the lab.

  As with the Mozart effect, one worrisome aspect of these video-game findings is that the majority of the evidence comes from a single group of researchers. Unlike with the Mozart effect, the group’s studies consistently appear in top-tier, peer-reviewed journals rather than obscure scientific backwaters. A bigger problem, though, is that training studies do not lend themselves to easy replication. Studies of the Mozart effect are easy to conduct—bring people into the lab for an hour, play them some Mozart, and give them a few cognitive tests. All you really need is a CD player and some pens. Studies of video-game training are much grander in scale. Each participant must be trained for many hours under direct supervision of laboratory personnel. That requires full-time research staff, more computers, a lot more money to pay subjects for their time, and the space to accommodate hundreds of subject-hours of testing. Few labs are devoted to doing this sort of research, and
those that are not typically don’t have the funding or resources available for a quick attempt at replication.

  To our knowledge, only one published study from a laboratory unaffiliated with the original researchers has successfully replicated the core result of the original Green and Bavelier article. In that study, Jing Feng, Ian Spence, and Jay Pratt of the University of Toronto showed that playing an action video game for ten hours improved the ability to imagine simple shapes rotating as well as the ability to pay attention to objects that the subjects were not directly looking at. They also found that women, who are on average somewhat worse than men on these spatial tasks, improved more from the training.65

  A second study, although not a direct replica of the Green and Bavelier experiment, did show a positive effect of video-game practice using a different game and a different subject population: seniors.66 This study addresses one of the major motivations for brain training: helping to preserve and improve cognitive functioning in aging. In this experiment, cognitive neuroscientist Chandramallika Basak and her colleagues randomly assigned one group of seniors to play Rise of Nations and another group to a no-training control condition. Rise of Nations is a slow-paced strategy game that requires players to keep track of a lot of information while switching back and forth between different strategic elements. The researchers’ hypothesis was that training on this sort of strategy game would improve what’s known as “executive functioning,” which is the ability to allocate cognitive resources effectively among multiple tasks and goals. Their study found substantial transfer from the video game to a variety of laboratory measures of executive functioning. That makes sense given the demands of the game, but because the study did not include any other games for comparison, it’s also possible that the benefits had nothing to do with being trained on this particular kind of video game, or indeed with video-game training at all. Seniors in the training group might simply have been more motivated to improve because they knew they were receiving special treatment as part of a study, and that motivation could have led to the biggest improvements for those tasks where they were already the most impaired.67