What exactly did you learn about the accuracy of 9/11 memories in the national survey?
It's important to mention that when we talk about "accuracy" here, we mean accuracy for details like, how did find you find out about 9/11, or who were you with? It's not the case that you don't have a fairly vivid image in your head of the planes crashing into the building. No one's forgetting 9/11 occurred.
Our measure of accuracy is consistency with what people told us in the survey the week after the attack. From that first survey to the second survey a year later, the overall consistency of the details of how they learned of 9/11 was only 63 percent. At the third survey, three years after the attack, consistency was 57 percent. So people were only a little more than 50 percent right for a lot of the details.
But they were particularly bad at remembering what their emotions were after 9/11—accurate only about 40 percent of the time, after a year. And yet overall, for all those details, people's confidence in their memories was, on average, greater than 4 on a scale of 1 to 5.
How well did people remember the facts about the attack itself?
They were better at memories for the facts of the attack than they were for their personal recollections. For instance, in recalling the number of planes involved, they were 94 percent accurate immediately afterward in the first survey, 86 percent accurate a year later, and 81 percent accurate three years later. But of course, those facts are supported by external reminders from media coverage.
An explicit example is that we also asked, "Where was President Bush when the attack happened?" Eighty-seven percent of people were accurate immediately after 9/11—but they dropped off to 57 percent and then went back up to 81 percent between the second and third surveys. We know that was due to a lot of people seeing or hearing about Michael Moore's film, Fahrenheit 9/11, which went over all the details that occurred.
Are there certain aspects of our personal recollections of 9/11 that look more reliable than others?
My research group at NYU has started to look at what kind of details are people better at and worse at in their emotional memories. Are there some details that are actually fine, that go along with the enhanced confidence you have in memory for details. And in a recent laboratory study—the paper is under review—we found that with memories for when and where, confidence does predict accuracy for emotional events, as well as neutral events. With when here, I mean the order of when one event happened relative to another event. We then went back to the 9/11 survey data, and we did see that memory was better for where than the other details. In recalling where they were when they learned of the attack, people were 89 percent accurate at survey two and 83 percent accurate at survey three.
Does it really matter if we don't have all the contextual details right in these emotional memories?
No. Again, I think we actually get better memory for the important details, but just worse memory for the other details. It's important to remember that the 9/11 attack occurred, right? I think—and it's just a theory—that part of why we have this super-enhanced feeling of remembering and sense of vividness for these highly emotional events is that knowing that they occurred matters a lot. Knowing the details about how they occurred, who told you about it, doesn't necessarily matter.
But the enhanced confidence that we have in the memory lets us rely on it and act quickly. You want to be confident of that previous memory, the main point of which was that there was this terrorist attack that could threaten my life and now I have to be wary of things that might be similar. Because you don't want to have to go, "Gee, does this remind me of anything...?" before you act on those types of threats in the future.