Why Do We Remember Some Life Moments—but Not Others?
Boston University neuroscientist Robert Reinhart (center) studied memory mechanisms with Wen Wen (left), a postdoctoral research associate, and Chenyang (Leo) Lin (GRS’30). Memory Why Do We Remember Some Life Moments—but Not Others? BU study finds memories of mundane incidents can be strengthened when they get attached to a memory of an emotionally charged event
Some memories are easy to recall—lush with detail, fresh as the moment itself. Others are more tenuous, like faded sketches. And the most stubborn ones can refuse to resurface at all. Why do our brains enshrine some memories so indelibly, and let others slip away?
A new Boston University study has a potential answer, suggesting that memories of mundane moments are given extra sticking power if they become connected to a significant event—something surprising, rewarding, or carrying an emotional punch. Watch your Powerball numbers cash in, for example, and you’re likely to remember what you were doing in the moments before, however unremarkable and unmemorable those incidents might have been otherwise. The findings, published in Science Advances, could potentially lead to improved treatments for people with memory problems or even help students retain tricky concepts.
“Memory isn’t just a passive recording device: our brains decide what matters, and emotional events can reach back in time to stabilize fragile memories,” says Robert M.G. Reinhart, a BU College of Arts & Sciences associate professor of psychological and brain sciences. “Developing strategies to strengthen useful memories, or weaken harmful ones, is a long-standing goal in cognitive neuroscience. Our study suggests that emotional salience could be harnessed in precise ways to achieve those goals.”
In their paper, he and his colleagues give the example of someone hiking through Yellowstone National Park and stumbling across a herd of majestic bison. The wow of that moment, they discovered, would not just cement the one magical experience in the mind, but lots of little, more run-of-the-mill events leading up to and away from it: a rock spotted on the path, a small animal darting into the undergrowth.
“The question is: What are the mechanisms for that?” says Reinhart, who’s also a College of Engineering associate professor of biomedical engineering and a faculty member at the BU Center for Systems Neuroscience. “That’s what we tried to uncover, how the brain selectively strengthens those fragile memories.”
How the Brain Selects Which Memories to Preserve
While most of us know that special moments get a revered spot in our memory banks, researchers have been divided on concepts known as retroactive and proactive memory enhancement—the prioritization of memories immediately before or after a big, or salient, event. Previous studies have disagreed on whether or not weaker memories are stabilized, or made easier to recall, by attachment to a more prominent one.
Reinhart says the latest project—which included close to 650 participants, 10 individual studies, and the use of artificial intelligence to analyze a broader set of data—is the first to definitively show that memory enhancement does happen. One major difference with past studies: they found the brain uses a sliding scale to decide which memories to preserve. Many of the team’s experiments involved showing participants dozens of images—connected to different levels of rewards—then giving them a surprise memory test the next day.
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