When the first plane hit, I was literally shaken out of the shower. What was that?

I remember the precise look on my roommate's face when I walked into the living room of the tiny tenement-style apartment we shared on the Lower East Side of Manhattan, about a mile from the World Trade Center: a mix of bewilderment, disbelief, and only a touch of the sarcastic smirk he typically wore. "Dude, you have to see this." The local-access cable news channel was flickering. We didn't know anything yet. They were reporting that a small aircraft, possibly a news helicopter, had accidentally struck one of the World Trade Center towers. There was no sense of scale or context yet. Just a confused series of conflicting reports and a smallish-looking, fuming hole in an iconic office building. It seemed serious, and like a possibly horrible accident, but it was still being treated with the WTF curiosity one might approach a turned-over tractor-trailer on the highway.

We went to the roof of our building to investigate. Immediately, we could see the gray-black smoke billowing from the North Tower. The tableau looked bigger, more foreboding than on our little TV. We could smell the smoke; taste the air. "Weird. Why would a helicopter be so close to the skyline anyway?"

Then, the second plane.

It was suddenly clear that this wasn't some terrible accident. Chaos and phone calls to loved ones followed. Most of the other tenants spilled onto the roof (a mix of the emerging freelance class, people with jobs that didn't require them to be in the office before 10 or so, and a handful of Hispanic families not yet forced out by the turn-of-millennia gentrification going on in the area at that time). With a crippled cell phone network and overwhelmed Internet, we all huddled around a handheld radio a neighbor had brought up. The president told us, in a shaky, metered voice, "America... is under attack." Elsewhere, we learned, a plane struck the Pentagon, and an unknown number of hijacked planes were still in the air. Behind us, above us, all around, smoke filled the air. Everything tasted like acid. The world seemed to be on fire.

And then the unthinkable: In almost uncanny slow-motion, the first tower collapsed.

As the reality of what just happened sunk in—untold thousands perishing before our eyes— there was mostly uneasy silence. Followed by tears. Between me, my roommate, and my almost-stranger building mates, there wasn't much to say. We traded dazed expressions, embarrassed re-introductions, and eventually helpful information when we could ("I hear the subways are down"; "I think Verizon's network is intermittently working if you want to borrow my phone"; etc.). I remember a quiet sort of human connection, a shared sorrow that was simultaneously devastating and uplifting. I hugged complete strangers. Neighbors cried on each other’s shoulders. Serena from the 3rd floor brought up a batch of fresh-baked corn muffins. And we all listened to the radio together.

A hectic day unfolded. The second tower collapsed. A plane went down in the woods somewhere. Some of us tried to go down to the site to “help” (whatever that meant), but the area was already sequestered off. Others went to find girlfriends, husbands, brothers. The rest of the day is something of a blur, as is most of that year. But that morning, exactly 10 years ago in a few weeks, is as clear as yesterday.

What's remarkable is that the confidence I have in this chain of events is matched only by the vividness with which it's recalled. My memory is real; it's fresh; it's as if I can still smell the smoke. It's also, in all likelihood, complete and utter bullshit.*

Or, to put it more politely, even though I'm especially confident in the accuracy of my recollection of 9/11, as neuroscientist Elizabeth Phelps explains in this video from the World Science Festival’s “The Unbearable Lightness of Memory,” the data strongly suggest otherwise.

Memories of tragic public events have been of interest to researchers for years. Dubbed as "flashbulb memories" for their extraordinary vividness of detail and photographic recall, these emotionally charged memories are described as being “burned” into one’s mind. Knowing exactly where one was or what one was doing during the assassination of John F. Kennedy, the Challenger disaster, or now, the September 11 attacks has become a quintessential phenomenon of the past few generations. In 1977, a pair of Harvard psychologists studied the reported memories of the JFK assassination. Participants had "an almost perceptual clarity" for recalling when they learned about the assassination and during the immediate aftermath, noting even trivial details with impressive accuracy. The researchers concluded that flashbulb memory is more detailed and accurate than memories of ordinary daily events. The defining characteristic of these types of emotionally charged, shared memories is that one's confidence in their accuracy tends to be unshakable. But does that really make them more accurate?

In an attempt to answer that, Duke University’s Jennifer Talarico and David Rubin conducted a study on the day after the 9/11 attacks. They gave volunteers a questionnaire about their memories of the morning of September 11 as well as some other unremarkable event a day earlier. They later followed up with the questionnaires at several intervals up until almost a year later. What the researchers found is that the memories of the individuals’ goings-on during the events of September 11—the vivid and picture-like ones—were in fact no better than their recall of, say, lunch the day before. Like most memories, they predictably declined in accuracy over time.

So what's going on? According to Phelps, it has to do with how a region of our brains, the amygdala, treats the perception of threat. The amygdala is the emotional center of the brain and has an influence over all stages of memory, from encoding to recollection. Over the past decade, Phelps’ lab at New York University has performed a series of experiments seeking to illuminate the interaction of emotion with memory, and specifically how it relates to the memory of the 9/11 attacks. Within three days of September 11, she and her colleagues set up a consortium of memory researchers to look at this phenomenon. Using fMRI, they looked at the brain systems involved when people retrieved memories from 9/11 experiences years later versus other life events that occurred during that time.

Not everyone had so-called flashbulb memories of the event, but many did. About half of the participants had exceptionally vivid recollections of the attacks, reporting specific details about sounds and smells. Remarkably, proximity to the actual World Trade Center site was the biggest indicator of flashbulb memory experiences. Those closer to the attacks in downtown Manhattan were significantly more likely to report vivid and confident recollections than those who experienced the event from farther away in NYC, perhaps through television, the Internet, or other secondhand reports. Personal involvement in an event seems to be critical for producing memories with such flashbulb qualities, as the amygdala is more active during firsthand experience.

This makes sense from an evolutionary perspective. Something significant happens; our amygdala is activated; and our brains tag the event so that we remember the apparent threat or otherwise emotionally charged episode. But if our memories of tragic events are just as suspect as any other memory, why do our brains tag them with such apparent detail?

It's worth noting that most of the enhanced recollection of reported flashbulb memories tends to focus on peripheral details and irrelevant ephemera: what one was wearing, what song was playing, whether it was cloudy. In other words, not exactly life-or-death factors. But these subtle details often make a better story, easy for retelling to others and, importantly, making the main aspect of the overall event easier to remember. Or as Phelps puts it, "You have very good perceptual experiences for the emotional event that's in the environment. But you can't look away; so you encode the details of other things worse."

So, in my case, during my up-close witnessing of the attacks, my amygdala lit up and said, "wow, this is big." But I didn’t necessarily sweat the details. Perhaps, at some point, somewhere in my head I made up a story post-hoc. And even though it's imperfect, with many of the nonmaterial details inaccurate, this story has stuck with me. I remember the lives lost. I remember my sense of naive security reshaped. I remember feeling the preciousness of life. I remember a community—and ultimately, a nation—coming together. Maybe my brain, in its infinite pattern-seeking ways, made up the story I know—a pat script that can be replayed in my head—precisely so that I remember those other things.

*Postscript:

After rehashing my recollection of that morning for the introduction above, I wanted to see how susceptible it was to what we know about flashbulb memory. I needed a second source in my roommate, whom I haven’t seen in years. On a lark, I found an old mutual friend on Facebook, and got my roommate’s email. I sent him my account of the events.

Instantly he poked holes. "Well, for one thing, we didn't have cable, so we weren't watching the news. We just used that TV to watch movies." Really? So was I in a neighbor's apartment, or did I fabricate that part altogether? "Also"—and this is a big one—"Serena didn't move in downstairs until a good year or so later." So, wait, who made the corn muffins? "Umm, I don't remember that at all; I mean why would we be eating muffins during all of that anyway?" He had a point. Others have questioned the plausibility of being "shaken out of the shower" by the impact of the first plane more than a mile away. The tumbling of one of the towers, maybe, but the plane impact wouldn't have that sort of seismic-like effect on my apartment, they argue. Many other irregularities have surfaced in my retelling after talking with other friends whom I saw that day.

But one thing my roommate mentioned struck me: "That thing about the shared sense of goodwill, though. Yeah I remember that; that was palpable, and stuck with me, too. How everyone—complete strangers—sort of pulled together in the face of tragedy. That was spot on."

And well, maybe that was the important part—the shared human connection despite the atrocities—that my brain wanted me to remember. Not whether I ate corn muffins.

Images: Paul Keller, via Flickr (top), and Elizabeth Phelps (bottom)