How Forgetting Helps Us Remember

Imagine if every time someone asked you for your address, you recalled that of your childhood home, college dorm, and your first apartment. Fortunately, all that usually comes to mind is the address of our current place of residence, but why is that?

A Stanford study shows that the brain suppresses, or forgets, less useful memories in order to prioritize important memories. The study, published in the June 3 issue of Nature Neuroscience, monitored individuals using an fMRI during three hours during memory tests in which participants memorized forty cue words and six associated words such as ATTIC-junk and ATTIC-dust.

The participants had to practice remembering the pairs and were given cues, such as ATTIC-j, to enhance their ability to remember ATTIC-junk over other competing word pairs. The students practiced the prompted word pair ATTIC-junk three times as the scanner recorded their brain activity. The first time they practiced a pair, the prefrontal cortex actively "lit up" as it worked hard to form the new memory while competing with the other word pairs. However, when the students practiced remembering the prompted word pair for a second and third time, their frontal lobes became less active. "Critically, we observed a relationship between the level of this decrease in prefrontal activity and how likely it was that the participant would later forget the competing irrelevant pairs," [doctoral student Brice] Kuhl said. After about 20 minutes, the volunteers were tested on all the word pairs and, as expected, they best remembered the pairs they had practiced and forgot the competing words. Moreover, the participants who forgot the most were the ones who showed the greatest decrease in prefrontal activity.

While similar effects have been observed before, this study is the first to show that forgetting actually benefits the brain by allowing neural systems to work less hard to recall priority information.

Read more: Forgetting helps you remember the important stuff, researchers say
ABSTRACT: Decreased demands on cognitive control reveal the neural processing benefits of forgetting