It happens to most of us: You walk into a room and forget what you went in there for. You misplace your keys, glasses, or phone. Or you can’t recall the name of the new person you just talked to a few hours ago.
However, we’re not supposed to remember everything, and we have the wrong expectations for memory, according to Charan Ranganath, a professor of psychology and neuroscience at the University of California, Davis. His latest book is Why We Remember: Unlocking Memory’s Power to Hold On To What Matters.
Ranganath tells KCRW that as people age, on average they experience a decline in episodic memory, which is the ability to recall events. However, some people never show a measurable decrease, while others have a steep drop. Scientists are still trying to understand why.
However, he assures us that our most common patterns of forgetfulness — like “where did I leave my wallet, where did I park my car?” — are not worrisome.
He also says no evidence suggests that people have a finite space in their brains to remember information.
“Our brains are very economical about how to store memories in the first place. … One school of thought, which I subscribe to, is that what the brain is optimized for is to give you the information that's new, surprising, biologically important — and to dump the rest. … So that's why we don't seem to hit these capacity limits.”
Why are we able to retrieve a memory during certain times but not others? Ranganath says there are many reasons — one is context.
“The place, the time, the emotions that you're feeling, background music, all these kinds of cues. And so there's often times where we're blissfully ignorant about some memory that's sitting there, and it seems to lay dormant. But then you go to a place that you haven't been to since you were a child, or you hear a song that you used to listen to during the summer when you turned 16, or you smell some food [that] reminds you of something that your grandmother cooked — and it just brings back a memory. … Part of that is because when you have reminders that take us back to a particular place of time, that can give you that sense of remembering that you otherwise wouldn't have.”
Sometimes people remember insignificant, random details as well. Ranganath points to data suggesting that attention regulation becomes more difficult with aging.
“We can be distracted by things that just grab our attention because we're not as good at being able to focus. … There's some data to suggest that even though older people, on average, are worse at remembering the things that they're supposed to, they can often be as good or better at remembering things that were inane.”
To improve our memory of what’s important, Ranganath recommends cutting distractions (such as notifications on your phone and computer), avoiding noisy environments, not multitasking, getting good sleep, eating healthily, and exercising.
He adds, “Then there's some real surprising ones that are just coming out. … For older people who have hearing problems, wearing a hearing aid can help with preserving memory over time. … Keeping oral hygiene can be related to maintaining good memory function as people get older.”
What about tips on studying for an exam? Ranganath’s advice is to harness “air-driven learning.” He explains, “The idea there is that you learn the most when you actually force your brain to struggle and pull out the information. … So for a student to test yourself instead of just studying the textbook over and over again — you actually get a lot more learning that allows the memory to last.”
He adds, “Anything that prompts you to really think about it and relate what you're seeing to your prior knowledge and to say, ‘Hey, this is new, and it changes the way I think about X,’ or ‘Hey, this relates to this other thing that I'm trying to study.’ … What happens is instead of having all these little fragments … you now have this rich network of ideas.”