The Invisible Gorilla: And Other Ways Our Intuition Deceives Us. Christopher Chabris
beating, and that evidence, combined with a misunderstanding of how the mind works, and the blue wall of silence erected by the other cops, led prosecutors to charge him with perjury and obstruction of justice. They, and the jury that convicted him, assumed that he too was protecting his comrades.
Kenny Conley’s conviction was eventually overturned on appeal and set aside in July 2005. But Conley prevailed not because the prosecutors or a judge were convinced that he actually was telling the truth. Instead, the appeals court in Boston ruled that he had been denied a fair trial because the prosecution didn’t tell his defense attorneys about an FBI memo that cast doubt on the credibility of one of the government’s witnesses.15 When the government decided not to retry him in September 2005, Conley’s legal troubles were finally over. On May 19, 2006, more than eleven years after the original incident on Woodruff Way that changed his life, Conley was reinstated as a Boston police officer—but only after being forced to redo, at age thirty-seven, the same police academy training a new recruit has to endure.16 He was granted $647,000 in back pay for the years he was off the force,17 and in 2007 he was promoted to detective.18
Throughout this book, we will present many examples and anecdotes, like the story of Kenny Conley, that show how everyday illusions can have tremendous influence on our lives. However, two important caveats are in order. First, as Robert Pirsig writes in Zen and the Art of Motorcycle Maintenance, “The real purpose of scientific method is to make sure Nature hasn’t misled you into thinking you know something that you actually don’t.”19 But science can only go so far, and although it can tell us in general how galaxies form, how DNA is transcribed into proteins, and how our minds perceive and remember our world, it is nearly impotent to explain a single event or individual case. The nature of everyday illusions almost never allows for proof that any particular incident was caused entirely by a specific mental mistake. There is no certainty that Conley missed the beating because of inattentional blindness, nor is there even certainty that he missed it at all (he could have seen it and then consistently lied). Without doing a study of attention under the same conditions Conley faced (at night, running after someone climbing a fence, the danger in chasing a murder suspect, the unfamiliar surroundings, and a gang of men attacking someone), we cannot estimate the probability that Conley missed what he said he missed.
We can, however, say that the intuitions of the people who condemned and convicted him were way off the mark. What is certain is that the police investigators, the prosecutors, and the jurors, and to some extent Kenny Conley himself, were all operating under the illusion of attention and failed to consider the possibility—which we argue is a strong possibility—that Conley could have been telling the truth about both where he was and what he didn’t see on that January night in Boston.
The second important point to keep in mind is this: We use stories and anecdotes to convey our arguments because narratives are compelling, memorable, and easily understood. But people tend to believe convincing, retrospective stories about why something happened even when there is no conclusive evidence of the event’s true causes. For that reason, we try to back up all of our examples with scientific research of the highest quality, using endnotes to document our sources and provide additional information along the way.
Our goals are to show you how everyday illusions influence our thoughts, decisions, and actions, and to convince you that they have large effects on our lives. We believe that once you have considered our arguments and evidence, you will agree, and that you will think about your own mind and your own behavior much differently. We hope that you will then act accordingly. So as you read on, read critically, keeping your mind open to the possibility that it doesn’t work the way you think it does.
The Nuclear Submarine and the Fishing Boat
Do you remember the first major international incident of George W. Bush’s presidency? It happened less than a month after he took office, on February 9, 2001.20 At approximately 1:40 p.m., Commander Scott Waddle, captaining the nuclear submarine USS Greeneville near Hawaii, ordered a surprise maneuver known as an “emergency deep,” in which the submarine suddenly dives. He followed this with an “emergency main ballast tank blow,” in which high-pressure air forces water from the main ballasts, causing the submarine to surface as fast as it can. In this kind of maneuver, shown in movies like The Hunt for Red October, the bow of the submarine actually heaves out of the water. As the Greeneville zoomed toward the surface, the crew and passengers heard a loud noise, and the entire ship shook. “Jesus!” said Waddle. “What the hell was that?”
His ship had surfaced, at high speed, directly under a Japanese fishing vessel, the Ehime Maru. The Greeneville’s rudder, which had been specially reinforced for penetrating ice packs in the Arctic, sliced the fishing boat’s hull from one side to the other. Diesel fuel began to leak and the Ehime Maru took on water. Within minutes, it tipped up and sank by its stern as the people onboard scrambled forward toward the bow. Many of them reached the three lifeboats and were rescued, but three crew members and six passengers died. The Greeneville received only minor damage, and no one onboard was injured.
What went wrong? How could a modern, technologically advanced submarine, equipped with state-of-the-art sonar and manned by an experienced crew, not detect a nearly two-hundred-foot-long fishing boat so close by? In attempting to explain this accident, the National Transportation Safety Board’s fifty-nine-page report exhaustively documents all of the ways in which the officers failed to follow procedure, all of the distractions they faced in accommodating a delegation of civilian visitors, all of the errors they made along the way, and all of the miscommunication that contributed to poor tracking of the Ehime Maru’s actual position. It contains no evidence of alcohol, drugs, mental illness, fatigue, or personality conflicts influencing the crew’s actions. The report is most interesting, however, for the crucial issue it does not even attempt to resolve: why Commander Waddle and the officer of the deck failed to see the Ehime Maru when they looked through the periscope.
Before a submarine performs an emergency deep maneuver, it returns to periscope depth so the commander can make sure no other ships are in the vicinity. The Ehime Maru should have been visible through the periscope, and Commander Waddle looked right toward it, but he still missed it. Why? The NTSB report emphasized the brevity of the periscope scan, as did Dateline NBC correspondent Stone Phillips: “…had Waddle stayed on the periscope longer, or raised it higher, he might have seen the Ehime Maru. He says there is no doubt he was looking in the right direction.” None of these reports consider any other reasons why Waddle could have failed to see the nearby vessel—a failure that surprised Waddle himself. But the results of our gorilla experiment tell us that the USS Greeneville’s commanding officer, with all his experience and expertise, could indeed have looked right at another ship and just not have seen it. The key lies in what he thought he would see when he looked: As he said later, “I wasn’t looking for it, nor did I expect it.”21
Submarines rarely surface into other ships, so don’t lose sleep over the prospect on your next boat trip. But this kind of “looked but failed to see” accident is quite common on land. Perhaps you have had the experience of starting to turn out of a parking lot or a side road and then having to stop suddenly to avoid hitting a car you hadn’t seen before that moment. After accidents, drivers regularly claim, “I was looking right there and they came out of nowhere…I never saw them.”22 These situations are especially troubling because they run counter to our intuitions about the mental processes involved in attention and perception. We think we should see anything in front of us, but in fact we are aware of only a small portion of our visual world at any moment. The idea that we can look but not see is flatly incompatible with how we understand our own minds, and this