Ever Wonder Why Some Memories Last A Lifetime? Science Explains

Some memories cling tightly, rich with detail, while others slip away almost as soon as they form. A new study from Boston University suggests that whether we hold onto a memory may depend on its connection to a meaningful event.

Published in Science Advances, the research reveals that even ordinary moments-like noticing a rock on a trail or sipping coffee at your desk-can gain staying power if they're linked to an emotionally charged or rewarding experience.

Emotional“glue” for fragile memories

“Memory isn't just a recording device,” says Robert M.G. Reinhart, associate professor of psychological and brain sciences at BU.“Our brains decide what matters. Emotional events can reach back in time to stabilize fragile memories.”

For example, if you win the lottery, you may not just remember the winning numbers-you'll likely recall the mundane moments before and after as well. The study shows that emotionally significant events can boost memory both retroactively (strengthening memories that came before) and proactively (cementing those that follow).

A large-scale test of memory

The research team, including nearly 650 participants across 10 studies, used images tied to different levels of reward to measure memory retention. With the help of AI to analyze results, they found that the brain uses a sliding scale: the stronger the emotional impact of an event, the more ordinary experiences around it are preserved.

Interestingly, retroactive memories-those that happened before the big event-were more likely to stick if they shared something in common with it, such as color or visual cues. This supports what the researchers call“graded prioritization,” a principle showing that the brain doesn't just save strong events but also protects weak ones that share conceptual overlap.

Why some details fade-and others don't

Lead author Chenyang (Leo) Lin, a BU doctoral student, explains:“For the first time, we show clear evidence that the brain rescues weak memories in a graded fashion. It's not just timing-it's also about similarity.”

The researchers also found that if another memory carried its own emotional weight, the brain was less likely to“rescue” surrounding weaker ones. In other words, the brain seems selective, choosing to preserve fragile details only when they're tied to the most meaningful moments.

From classrooms to clinics

Beyond understanding how memory works, the findings could be applied in education and healthcare. Pairing emotional or engaging content with difficult material could help students retain information. Clinically, it might open ways to strengthen fading memories in aging adults-or, conversely, to avoid reinforcing traumatic ones.

“This discovery has broad implications,” Reinhart says.“It could help us design new strategies to boost learning, support healthy aging, and even guide treatments for memory-related disorders.”

The study was supported by the National Institutes of Health, the International OCD Foundation, and other partners.

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