If you're an American of a certain generation you can almost certainly remember the exact moment you learned that President Kennedy had been shot. And most adults over 30 have similarly vivid memories of what they were doing on September 11th, 2001. Personal tragedy or joy can similarly sear highly emotional memories in your mind.

Psychologists call these moments flashbulb memories, as they feel detailed and bright, just like a moment captured in time by a camera. But here's the other thing psychologists say about these "flashbulb memories" - they're actually hugely likely to be totally inaccurate.

Vivid does not equal accurate.

As psychologist Susan Weinschenk explained on her behavioral science blog, there's a solid biological explanation for why we remember these flashbulb moments so vividly: "Emotions are processed in the amygdala part of the mid-brain, and the amygdala is very close to the hippocampus. The hippocampus is involved in the long term coding of information into memories. So it is no surprise to psychologists that emotionally laden memories might be very strong and remembered vividly."

But just because these images feel like they are carved into our brains, doesn't mean they are actually as permanent and unchanging as they seem to be. Researcher Ulric Neisser demonstrated this with a clever and forward-thinking experiment in 1986, the year the space shuttle Challenger exploded.

The day after the tragedy, Neisser had his students write down their memories of the event - things like where they were, what they were wearing, etc. Three years down the line he quizzed them about what they remembered about that day again. How did they do?

In a word, terrible.

"Most (over 90 percent) of the three-year later reports differed. Half of them were inaccurate in 2/3 of the details. One person, when shown her first description written three years earlier, on the day after the event, said, 'I know that's my handwriting, but I couldn't possibly have written that.' Similar research has been conducted on the 9/11 memories, with similar results," reports Weinschenk.

This isn't, she goes on to explain, because flashbulb memories are particularly prone to decay and revision. It's simply that all our memories are this unreliable. It's just that flashbulb memories feel different and more lasting, so this comes as more of a shock to us.

Trust flashbulb memories at your peril.  

What's the takeaway here? Beyond the simple fascination factor, these findings obviously have implications for anyone in law enforcement who relies on remembered testimony to piece together what happened during a crime. But it also has implications for marketers, Weinschenk notes.

"We often ask customers to remember a particular encounter with a website, software, or an in-store experience. We may have to realize that the memories, although vivid, might not be accurate," she cautions. ?