Читать книгу The Invisible Gorilla: And Other Ways Our Intuition Deceives Us - Christopher Chabris - Страница 25

Try to recall exactly where you were when you first heard about the attacks of September 11, 2001. If you’re like us, you have a vivid memory of how you learned about the attacks, where you were, who else was with you, what you were doing immediately beforehand, and what you did immediately afterward. Chris recalls waking up late that morning, after the first plane had hit the World Trade Center. He listened to the Howard Stern Show on the radio until it ended around noon, at which point he turned on the TV. He got in touch with an Israeli colleague, who told him it was already obvious who the perpetrators must be, and he received an e-mail update from a friend who was living in Brooklyn, watching the events safely from her rooftop. He received another e-mail from the manager of his office building at Harvard, William James Hall, recommending evacuation.

Dan recalls working in his office that morning when his graduate student Stephen Mitroff came in to tell him that a plane hit the first tower. He spent the next few minutes seeking information online, and when the second plane hit, he turned on the television in his lab and he and his three graduate students watched the towers collapse. He then spent a few frantic minutes on the phone trying to reach his brother David’s girlfriend because David was traveling back from New York to Boston that morning (he was sitting on a plane waiting to take off from LaGuardia Airport when the attacks happened). Dan remembers becoming concerned that the fifteen-story building he was in might also be a target. He left before noon to pick up his wife in downtown Boston and they went home together and watched the television coverage for the rest of the day.

Neither of us has any idea what we were doing or whom we talked to the day before 9/11. We suspect that the same is true for you. Your memories of 9/11 are more vivid, detailed, and emotional than your memories of more ordinary events from that time period. Memories of dramatic events of personal or national importance often are recalled in greater detail. Some significant events appear to be imprinted in our minds in a way that lets us play them back in video-like detail, perfectly preserved despite the passage of time. This intuition is powerful and pervasive. It is also wrong.

Such detailed memories for a significant event were first studied systematically in 1899 by Frederick Colgrove as part of his doctoral research at Clark University. Colgrove asked 179 middle-aged and older adults where they were when they heard about the assassination of Abraham Lincoln.³⁴ Even though he asked people to recall events that happened more than thirty years earlier, 70 percent remembered where they were and how they heard about it, and some provided exceptional amounts of detail.

Nearly eighty years later, social psychologists Roger Brown and James Kulik coined the term flashbulb memories to characterize these vivid, detailed memories for surprising and important events.³⁵ The name, by analogy to photography, reflects the idea that the details surrounding surprising and emotionally significant events are preserved in the instant they occur: Events meriting permanent storage are imprinted in the brain just as a scene is imprinted onto film. According to Brown and Kulik, the memory is “very like a photograph that indiscriminately preserves the scene in which each of us found himself when the flashbulb was fired.”

In their study, Brown and Kulik surveyed eighty Americans (forty black and forty white) about a variety of events, most of which involved assassinations or attempted assassinations in the United States during the 1960s and 1970s. Much as Colgrove did before them, Brown and Kulik documented that all but one of their subjects had a flashbulb memory for the Kennedy assassination. Majorities had flashbulb memories for the assassinations of Bobby Kennedy and Martin Luther King, and many had flashbulb memories for other similar events.

In their research papers, Colgrove and Brown and Kulik provided vivid examples from their own memories to go along with the detailed, emotionally charged recollections their subjects had for these political assassinations. We all have such flashbulb experiences, and we can retrieve them with ease and fluency. Recounting or asking about a flashbulb memory can start a conversation that goes on for hours; try it the next time you’re at a boring dinner party. It is the richness of these particular recollected experiences that leads us to believe so strongly in their accuracy. Ironically, the conclusions drawn from the initial research on flashbulb memories were based entirely on the illusion of memory. The recollections of their subjects were so vivid and detailed that the researchers assumed they must be accurate.

After writing down his personal recollection of 9/11 for this book, Dan e-mailed his former students and asked them to send him their own for comparison. The first to respond was Stephen Mitroff, now a professor at Duke University:

I got an email from my girlfriend saying a plane hit the World Trade Center. I did a quick look at CNN and then went into your office where you and Michael Silverman were chatting. I told you. We went back to my office and we were looking at the images on Steve Franconeri’s computer. You surmised it must have been a small plane and the pilot lost control. We saw a picture of a huge commercial plane right next to the tower and you thought it must be a Photoshopped pic. We looked at various websites, including airline sites to look at the status updates of the flights that were being reported as hijacked. After more web searching, you hooked up the TV in our testing room and lots of people watched more in there. I think we witnessed one of the towers collapse, but I am not confident in that. We definitely were watching during one of the key events. We all started to feel an unwarranted uneasiness over being in the tallest building in town and left before lunch time. Michael and I walked back to Boston…

Dan’s other two graduate students at the time both reported being away from the lab that morning, so they could not have followed the news reports with Dan. Mitroff remembered Michael Silverman—Dan’s postdoctoral fellow at the time, now a professor at Mount Sinai School of Medicine—being in Dan’s office but Dan did not. Dan e-mailed Silverman the same question he had asked the three Steves. The following report came back:

I was standing in your office discussing something with you. The radio on your bookshelf was on. Mitroff yelled from his office something to the extent that CNN was reporting that a plane just flew into the World Trade Center. I went to his office to see but the page was loading very slowly. I mentioned that little planes fly the Hudson corridor regularly, so I guessed it was possible. The page loaded and it showed a large plane flying toward the WTC. I said something to the extent that putting up a Photoshopped image like that was disgusting—I was still convinced that only a small plane had crashed. The next information we received came from your radio (CNN was slow and not loading anything additional). We heard that not one but two planes had hit. I then went to my office and tried to call my wife. She was also trying to call me. Neither of us could get through…When I left my office, someone had turned on a television in the testing room. The picture was noisy. It showed that one tower had already dropped and we watched the second one fall. (I’m not sure if the second tower falling was live, but I suspect it wasn’t.) You made the decision for us to leave and go home around 11:00. Mitroff and I walked to his apartment and then I walked home.

There are interesting similarities and differences among these accounts. First the similarities: Everyone agrees that Dan heard about the attack from Steve Mitroff, they spent some time searching online for information, and then Dan turned on the television in the lab where he and Mitroff watched footage of a tower collapsing. Now for the differences: Dan did not recall Michael Silverman being present and he mistakenly remembered his other graduate students being there. All three remember Mitroff coming into Dan’s office, but Silverman remembers Mitroff yelling from his office first. Dan recalled nothing about a discussion of the image of a plane next to the tower; Mitroff recalled Dan commenting that the plane was small and that the image of a larger plane was edited; and Silverman recalls making those comments himself.

Three cognitive psychologists had vivid memories for what they experienced on 9/11, but their memories conflicted in several ways. If memory worked like a video recording, all three reports about 9/11 would be identical. In fact, there is no way to verify which of the accounts is most accurate. The best we can do is to assume that two independent and mutually consistent recollections are more likely to be correct than one recollection that conflicts with both. Many cases of memory failure are just like this, in that there is no documentary evidence to establish the ground truth of what actually happened.

In some cases, like Neil Reed’s confrontation with Bobby Knight, it is possible to compare people’s recollections to documentary evidence of what actually happened. President George W. Bush experienced a similar distortion to his memory of how he first learned about the attacks on the morning of 9/11. You might recall the video footage of Bush reading the story “The Pet Goat” to an elementary school class in Florida when his chief of staff, Andrew Card, walked in and whispered in his ear. His stunned reaction provided fodder for comics and commentators alike. That moment, caught on video, was how he heard about the plane hitting the second tower. It was his moment of realization that the United States was under attack. He’d already heard about the first plane before entering the classroom, but like many in the media, he believed that crash to have been a small aircraft accidentally veering into the tower.

On at least two occasions, Bush publicly recalled having seen the first plane hit the tower on television before entering the classroom. For example, on December 4, 2001, in response to a question from a young boy, he recalled, “I was sitting outside the classroom waiting to go in, and I saw an airplane hit the tower—the TV was obviously on, and I use[d] to fly myself, and I said, ‘There’s one terrible pilot.’ And I said, ‘It must have been a horrible accident.’” The problem is that the only video footage broadcast the day of the attacks was of the second plane. There was no video footage of the first plane’s impact available until long afterward.³⁶ Bush’s memory, although plausible, could not have been right. He correctly recalled Andrew Card entering the classroom following the crash of the second plane and telling him that America was under attack, but his memory of how and when he first heard about the attacks mixed up these details in a plausible but inaccurate way.

There was nothing necessarily malicious in Bush’s false memory—details sometimes shift in memory from one time to another or from one event to another. Yet conspiracy theorists, suffering from the illusion of memory (among other things), decided that Bush’s false recollections were not false at all, but Freudian slips that revealed a hidden truth. He said that he saw the first plane crash on television, so he must have seen it. And if he saw it, whoever shot that secret footage must have known where to point a camera in advance, so Bush must have known the attack was going to happen before it did. The illusion of memory made some people jump to the conclusion that the government deliberately permitted or possibly even planned the attacks, skipping right over the more plausible (but less intuitive) explanation that Bush simply conflated some aspects of his memory for the first and second plane impacts in the attack.³⁷

Experiments building on Brown and Kulik’s article on flashbulb memories have sought ways to verify the accuracy of these memories, often by obtaining recollections immediately after some tragic event and then testing the same people months or even years later. These studies consistently find that flashbulb memories, although richer and more vivid, are subject to the same sorts of distortions as regular memories. On the morning of January 28, 1986, the space shuttle Challenger exploded shortly after takeoff. The very next morning, psychologists Ulric Neisser and Nicole Harsch asked a class of Emory University undergraduates to write a description of how they heard about the explosion, and then to answer a set of detailed questions about the disaster: what time they heard about it, what they were doing, who told them, who else was there, how they felt about it, and so on.³⁸ Reports like these, written as soon as practicable after the event, provide the best possible documentation of what actually happened, just as the video of Bobby Knight and Neil Reed recorded the reality of the choking incident.

Two and a half years later, Neisser and Harsch asked the same students to fill out a similar questionnaire about the Challenger explosion. The memories the students reported had changed dramatically over time, incorporating elements that plausibly fit with how they could have learned about the events, but that never actually happened. For example, one subject reported returning to his dormitory after class and hearing a commotion in the hall. Someone named X told him what happened and he turned on the television to watch replays of the explosion. He recalled the time as 11:30 a.m., the place as his dorm, the activity as returning to his room, and that nobody else was present. Yet the morning after the event, he reported having been told by an acquaintance from Switzerland named Y to turn on his TV. He reported that he heard about it at 1:10 p.m., that he worried about how he was going to start his car, and that his friend Z was present. That is, years after the event, some of them remembered hearing about it from different people, at a different time, and in different company.

Despite all these errors, subjects were strikingly confident in the accuracy of their memories years after the event, because their memories were so vivid—the illusion of memory at work again. During a final interview conducted after the subjects completed the questionnaire the second time, Neisser and Harsch showed the subjects their own handwritten answers to the questionnaire from the day after the Challenger explosion. Many were shocked at the discrepancy between their original reports and their memories of what happened. In fact, when confronted with their original reports, rather than suddenly realizing that they had misremembered, they often persisted in believing their current “memory.”

Those rich details you remember are quite often wrong—but they feel right. As Neil Reed said about his memory of being choked by Bobby Knight, after seeing the videotape of what really happened: “As far as people coming in between, I remember people coming between us.”³⁹ A memory can be so strong that even documentary evidence that it never happened doesn’t change what we remember.