We all would like to improve our memories, especially as we enter midlife and worry that it might be getting worse. It's annoying to forget where you put things, people's names or important information we need to help us get by at work or with friends. As you frantically try to recall what you forgot, your panic only grows along with your frustration.
Traditionally, psychology tells us that the best way to keep memories alive is to rehearse them over and over again. Practice makes perfect, so we think that the more we work over that information we're trying to keep alive in memory, the more likely it will be to stick in our brains. However, this might not be the best strategy, according to new research conducted by University Hospital of Magdeburg, Germany's Maria Wimber (2015) and co-authors. They examined what they called the "dark side" of memory in which you try to recall one of two competing facts in memory.
According to Wimber's "response competition theory," the more you try to remember one of those facts, the more likely it is you'll forget the other one. If you actually need to remember both of them, then, that second previously-unrecalled memory will fade over time. In fact, that second memory will actually become suppressed, not merely forgotten.
In the experiments that Wimber and her team conducted, participants completed a two-phase experiment. In Phase 1, participants were trained to remember one set of word -- image pairs (such as Marilyn Monroe's face paired with the word "sand"). In Phase 2, they saw a new set of images that they were told to associate with the same words (such as hat). In the test phase, participants were told to indicate which category of image was associated with the word (in this case, face or object). The cool part of this study was that prior to the test phase, the Wimber team identified the brain activation associated with both the target (Marilyn Monroe) and the competitor (hat). Over repeated trials, not only did brain activation for Marilyn's face increase when they saw the word "sand," but the traces for "hat" sunk below the initial baseline.
Our brains, then, seem to banish the information we no longer need in memory -- not just forget it, but inhibit it altogether. Although this can get you in trouble, it can also prove very adaptive. You need useless knowledge to be driven out of your mind or it will keep interfering with what you need to know. Your brain helps you accomplish this important feat.
Now you know how your brain tries to help you become more efficient at remembering what you need when one set of information can interfere with another. How can you turn this around to help you remember what you don't necessarily, but might, need to remember? Consider what happens if you have two passwords for two different online accounts. One is for an account you hardly ever use, and one is for one you use every day. The more you retrieve the password you use on a daily basis, the more likely it is you'll forget the less frequently-visited site. You'll need to put in extra effort to counteract the tendency your brain has to suppress useless information.
It's because our memories are adaptive that they're so fallible. Instead of blaming your poor memory each time you forget, this research shows that you can congratulate it for being so good.
Wimber, M., Alink, A., Charest, I., Kriegeskorte, N., & Anderson, M. C. (2015). Retrieval induces adaptive forgetting of competing memories via cortical pattern suppression. [Article]. Nat Neurosci, advance online publication. doi: 10.1038/nn.3973
If you'd like more detail on the study, please check out my Psychology Today blog on the topic.