I was living in Manhattan on 9/11. I can vividly recall the horrifying details of the day. I can still smell the acrid odor of burnt plastic and the pall of oily smoke and the feeling of disbelief, the sense that history had just pivoted in a tragic direction. Such vivid, visceral, emotional memories are known as flashbulb memories. They are defined by their cinematic feel, how they are dense with sensory detail. They also feel especially accurate: I’m completely convinced that my 9/11 memories are uncommonly precise, permanently etched into my hippocampus. But I’m wrong. My memories of 9/11 are just as dishonest and flawed as the rest my memories. Here’s the abstract:
On September 12, 2001, 54 Duke students recorded their memory of first hearing about the terrorist attacks of September 11 and of a recent everyday event. They were tested again either 1, 6, or 32 weeks later. Consistency for the flashbulb and everyday memories did not differ, in both cases declining over time. However, ratings of vividness, recollection, and belief in the accuracy of memory declined only for everyday memories. Initial visceral emotion ratings correlated with later belief in accuracy, but not consistency, for flashbulb memories. Initial visceral emotion ratings predicted later posttraumatic stress disorder symptoms. Flashbulb memories are not special in their accuracy, as previously claimed, but only in their perceived accuracy.
In my book, I spend a lot of time explaining why our memories are so imperfect. It turns out that the act of remembering a memory actually changes the memory itself. (This is known as memory reconsolidation.) Although we like to imagine our memories as immutable impressions, like a data file on a computer hard drive, our memories are actually a ceaseless process. Every time we remember anything, the neuronal structure of the memory is delicately transformed, a process called reconsolidation. (Freud called this process Nachtraglichkeit, or “retroactivity”.) The memory is altered in the absence of the original stimulus, becoming less about what you remember and more about you.