We all complain about how lousy our memories are. But forgetting is one of the most important tasks your brain undertakes. In fact, your brain intentionally and immediately discards almost everything you experience. Sounds persist for a few seconds before they are irretrievably lost. Images are trashed after at most a half-second. Try it yourself: Close your eyes and count the letters in this sentence.
Even when something survives all of these filters, it usually vanishes soon after. How many times have you been introduced to someone only to have no idea what their name is after a minute or two?
What’s going on here? Why is your brain so intent on throwing away everything you work to learn?
A popular myth is that you’ve got limited space and your brain is aggressively trying to make room for new information. In reality, anything you’ve stored lasts nearly forever. You just lose access to it—which is why you have an “ohhh yeah” moment when you find your keys. Of course that’s where you put them. The information was in there. You just couldn’t access it.
It turns out that forgetting—in the form of this loss of access—is an adaptation. Consider the horror of perfect memory: You’d remember with perfect clarity every time you made a mistake, and every time someone was rude to you, and every time you hurt someone’s feelings. You’d call to mind every phone number—yours and others’—equally well. You’d vividly recall every time you bit your tongue, and every time you inhaled. You’d go insane.
So how do we remember anything?
Researchers in the psychological sciences have catalogued dozens of triggers that cause your brain to hold onto information. An example is when you encounter something repeatedly, especially if those encounters are spread out in time. Your brain expects it to come up again in the future, and so information about it is preserved. This “spacing effect” works on such a fundamental neurological level that it is even found in the not-quite-brains of sea slugs!
Another trigger is the retrieval of information from in your brain. People who prepare for a test by calling the material up from memory get good at bringing it up from memory. People who prepare for a test by re-reading the material get good at reading the test questions, but not knowing the answers.
These triggers operate on mechanisms beyond your conscious control. We’ve all thought “Jeez I really need to remember this” only to have it suffer the same fate as almost everything else. You may think something is important, but your brain doesn’t care what you think.
Instead, you need to use the triggers to get your brain to agree with you that something is important. For remembering someone’s name, you can test yourself under your breath. For more complex materials, you may want to rely on software that incorporates research on these cognitive triggers.
And the next time you blank on a movie star’s name—but still recall the entire theme song to a cartoon you haven’t seen since you were six-going-on-seven—remember that these are side effects of your brain generally taking pretty good care of you.