100 Things You Should Know About People: #41 — Your Most Vivid Memories Are Wrong

Ebbinghaus Forgetting Curve
Ebbinghaus Forgetting Curve

If I ask you to remember where you were and what you were doing when you first heard about the September 11, 2001 attacks in New York City, chances are very good that you will be able to tell me in great detail your memory of that day, and how you heard about the attacks. Especially if you live in the US and you were 10 years old or older on that date. But the research shows clearly that you would be wrong about the majority of your memory.

Flashbulb memory is very vivid — Remembering traumatic or dramatic events in great detail is called “flashbulb memory” by psychologists, and has been studied for several decades. 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 the memories are full of errors — It turns out, though, that those memories are full of errors. Ulric Neisser researches memories like these. In 1986 the space shuttle Challenger exploded upon take-off. Any of you reading this who are old enough to remember the Challenger explosion probably remember it vividly, i.e., as a flashbulb memory. Neisser took the opportunity to do some research. The day after the explosion he had his students (he is a professor) write down their memories of what had happened, where they were, what they were wearing, what the TV coverage was like, etc. Three years later he asked them to write down their memory of the event again. Most (over 90%) of the 3-yr 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.

The Forgetting Curve of 1885 — In 1885 Hermann Ebbinghaus created a formula showing the degradation of memories:

Re(−t/S)

where R is memory retention, S is the relative strength of memory, and t is time. The graph at the top of this post is an example of this formula. It’s called the “Forgetting Curve”. Because flashbulb memories are so vivid, it was thought that perhaps they were not as subject to forgetting as other memories. But it turns out they are. Which is kind of disturbing, when you think about it. Because they are so vivid, we are SURE they are accurate and real. But they aren’t nearly as accurate as we think.

Take-Aways – I can think of many ways that we (falsely) rely on people’s memories of events, whether dramatic or not: for example, conducting user or customer research. 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.

What do you think?  Can you think of situations where you perhaps rely on people’s memories more than you should?

For more reading and information:

Kathryn Schulz, Being Wrong, Harper Collins, 2010

Daniel Schacter, The Seven Sins of Memory, Houghton Mifflin, 2001

Neisser and Harsh, “Phantom Flashbulbs: False Recollections of Hearing the News about Challenger”, in Winograd and Neisser (eds) Affect and Accuracy in Recall, Cambridge University Press, 1992, p. 9-31.

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