FLASHBULB MEMORIES: A national study of 9/11 memories conducted by researchers at intervals of one week, one year and three years after the September 11, 2001 attack included more than 3,000 people in New York City, Washington, D.C., Boston and elsewhere. Last month, the scientists did a 10-year follow-up, making the project the longest prospective study of how flashbulb memories change over time. Image: COURTESY OF NATHAN SIEMERS, VIA FLICKR
For most Americans, as the nation's thoughts turn to the 10th anniversary of the 9/11 terrorist attacks, memories of that day readily come flooding back. People can remember with great clarity what they were doing or to whom they were speaking when they learned of the crisis—whether via a sister's phone call or a first-hand glimpse of the World Trade Center on fire.
Decades ago, psychologists theorized that the brain imprints such details into its memory, like a photograph, when we learn of sudden, tragic national events. These highly emotional recollections were dubbed "flashbulb memories"—but the notion of photographic accuracy didn't bear out in later research. [For more about the psychology of 9/11, read the Streams of Conscious blog, "Forgetting About 9/11"]
How much can we trust, then, of what we remember of 9/11? Some answers are provided by a national study of 9/11 memories conducted by researchers at intervals of one week, one year and three years after the attack. The team surveyed more than 3,000 people in New York City, Washington, D.C., Boston, and four other cities in Connecticut, Missouri and California. Last month, the scientists did a 10-year follow-up survey—data yet to be analyzed—making the project the longest prospective study of how flashbulb memories change over time. Scientific American spoke with New York University psychologist Elizabeth A. Phelps, a lead investigator of the survey.
[An edited transcript of the interview follows.]
New York University (NYU) is only two miles from the World Trade Center site. What was it like when you got to your lab the morning of 9/11?
By then, the second plane had hit the towers. There was nobody else in the office at that point, but one person. I went to his office, which looked out at the World Trade Center, and we saw one tower go down. You just couldn't even believe it. And then it was kind of a weird day. Some people came into the office. You really couldn't focus on work. So eventually I went home, watched CNN and ended up trying to go give blood.
How did the 9/11 memory project come about?
Phone service was hit or miss that day, but John Gabrieli, a friend and neuroscientist who was then at Stanford, managed to call me. He just wanted to make sure I was okay. We started talking about doing a study of 9/11, because every memory researcher knows about the classic studies of memories of the Challenger space shuttle explosion or the 1989 San Francisco earthquake. Then after a day or so, we decided to do it.
We worked very fast. John started putting the survey questionnaire together with Kevin Ochsner, a postdoc in his group. We got in touch with Bill Hirst, Marcia Johnson, Chandan Vaidya and other researchers who joined the consortium. By September 18, we had survey tables in front of the NYU library and in Washington Square, and Bill [Hirst] had tables up around 14th Street, at the New School for Social Research. Right after 9/11, people in New York really wanted to be around other people and to do things that were helpful. And I think taking our survey was something that people thought would contribute to the greater good.
My entire lab worked on the 9/11 project. At the time, it would have been hard for us to work on anything else. The streets were closed around NYU and the campus shut down. The study helped us stay busy and yet feel relevant to what was going on.
How does emotion in a traumatic event like 9/11 influence our memories?
Emotion kind of focuses you on a few details but lets you ignore other details. And if you are highly aroused by fear, that emotion helps you store things in your memory better, in a storage process called consolidation that depends on the interaction of the amygdala and hippocampus. But what we've known for a while is that emotion gives you a stronger confidence in your memory than it does necessarily in the accuracy. Usually, when a memory has highly vivid details and you're confident in those details, that means you're likely to be right. Confidence often goes hand in hand with accuracy. But when something is highly emotional, they often get separated.
So if you look at memory for 9/11, pretty much everybody would say, "I know where I was, who I was with," etc. etc. Everyone thinks, "Oh, I never would forget that." But we know from a lot of studies from the past 30 years that people aren't necessarily right. You can't even convince people that their memories are wrong. All you can say is that data would suggest your memory's wrong.
With emotional events like 9/11, I think we do have better memory for the important details [as compared with a neutral event]—we just don't have great memory for all the details. And we think we do, and that's the real contrast. Whereas, if I told you that you don't remember the details of your 26th birthday, you wouldn't be surprised, necessarily.