A friend the other day mentioned a fellow of her acquaintance who likes a good story so much that he frequently embellishes — and then tells the story so many times that he starts to believe the embellishment. He should meet neuroscientist Karim Nader, who had a clear memory of a 9/11 event he couldn’t possibly have experienced. Scientific American Smithsonian picks up the story:

Like millions of people, Nader has vivid and emotional memories of the September 11, 2001, attacks and their aftermath. But as an expert on memory, and, in particular, on the malleability of memory, he knows better than to fully trust his recollections.
Most people have so-called flashbulb memories of where they were and what they were doing when something momentous happened: the assassination of President John F. Kennedy, say, or the explosion of the space shuttle Challenger. (Unfortunately, staggeringly terrible news seems to come out of the blue more often than staggeringly good news.) But as clear and detailed as these memories feel, psychologists find they are surprisingly inaccurate.
Nader, now a neuroscientist at McGill University in Montreal, says his memory of the World Trade Center attack has played a few tricks on him. He recalled seeing television footage on September 11 of the first plane hitting the north tower of the World Trade Center. But he was surprised to learn that such footage aired for the first time the following day. Apparently he wasn’t alone: a 2003 study of 569 college students found that 73 percent shared this misperception.
Nader believes he may have an explanation for such quirks of memory. His ideas are unconventional within neuroscience, and they have caused researchers to reconsider some of their most basic assumptions about how memory works. In short, Nader believes that the very act of remembering can change our memories.

His findings might actually help PTSD sufferers.