The Invisible Gorilla: And Other Ways Our Intuition Deceives Us. Christopher Chabris
news stories about end-of-life issues. What is striking is that 75 percent of the people who changed their minds were unaware that they had done so! They thought that the decision they reported in the second interview was the same as their decision in the first interview. Their memory for what they had said earlier was rewritten to match their current beliefs.
The illusion of memory leads us to assume—unless we receive direct evidence to the contrary—that our memories, beliefs, and actions are mutually consistent and stable over time. Amid the national grief after President Kennedy was assassinated, a poll showed that two-thirds of people claimed they had voted for him in the 50/50 squeaker election of 1960.33 At least some of them must have revised their memories of how they voted three years earlier, probably to make them consistent with the positive feelings they had about their fallen leader. More broadly, we tend to assume that everything in our world is stable and unchanging unless something draws our attention to a discrepancy. When our beliefs change, though, our memories can change along with them. A living will you produced a few years ago may not reflect your current preferences—but you are likely to misremember its contents and assume that it expresses what you want today. If you become seriously ill and are unable to communicate, doctors will rely on this document and may inadvertently take actions that contradict your wishes.
Where Were You on 9/11?
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