Remember the game "telephone"? Someone starts by saying a sentence to the person next to them. That person then turns to someone else and repeats what they heard. Somehow, by the time the sentence gets to the last person in line, it's all mixed up and barely resembles the original.
Apparently our memories operate in the same way.
A study published recently in the Journal of Neuroscience looks at how we retrieve memories. It's a well-known phenomenon that retrieval is good for memory - the more you remember something, the longer you'll remember it for.
The catch, researchers have discovered, is that each time you retrieve a memory you forget or add small things to it, and the next time you recall the information, you'll remember what you remembered.
"Our memories aren't like a photograph," says lead study author Donna Bridge. "We mix up details, we forget things. We're likely to remember this incorrect information just as much as we are the correct (memory)."
In other words, the more you recall an event, the more distorted your memory of that event may be.
Bridge, a postdoctoral fellow at Northwestern University's Feinberg School of Medicine, asked 12 participants to take a memory test on three subsequent days. The first day, study participants repeatedly placed 180 objects in an assigned location - different for each one - on a computer screen grid. The second day they were asked to place those objects in the same positions. Twenty-four hours later, they did it again.
Bridge measured the distance between where participants placed the object and the correct assigned location. She found that by the third day, participants were placing the object much closer to where they placed the object on the second day than where it was supposed to go.
"This act of remembering ... is an experience in itself," Bridge says. "You might not even be able to distinguish between the original memory and the subsequent event of remembering it."
The researchers have a couple of theories as to what exactly is happening.
One is that it's an access problem. Your brain could be like a really full closet - each time you remember something, your brain creates a new item similar to the first and stores it up front. When you go to grab that memory again, you grab the one that's easiest to access.
The other theory is that your brain has a storage problem. Imagine a school locker full of books, binders and miscellaneous junk. Every time you open that locker to grab the memory something falls out, or your brain throws in whatever you happen to have in your hands. Next time you open the locker your keys are missing and a new set of pens has magically appeared.
In a way, the results of the study are kind of creepy. If every memory you have is like the last sentence in a game of telephone, how close is it to what actually happened?
"It makes you question everything about how the system works," Bridge says with a laugh.