Emotional Events Can Strengthen Earlier Ordinary Memories

When people experience striking events, not only do those moments become etched in memory, but even seemingly ordinary experiences that occurred shortly before can become unusually vivid. The neural mechanism behind this effect has been further clarified in a new study published in Science Advances, which supports the "tag-and-capture" theory of memory consolidation.

According to this theory, everyday experiences leave temporary chemical "tags" on neurons. If a highly emotional or significant event occurs soon after, it triggers a burst of protein synthesis in the hippocampus and related brain regions. The earlier tags can then "capture" these newly synthesized proteins, transforming otherwise weak and fleeting memories into more lasting ones, bound together with the stronger emotional memory.

To test this mechanism, a team at Boston University designed an experiment in which participants viewed images of animals and everyday tools. Later, they were asked to classify the images to earn rewards of varying value (high reward: 900 points; low reward: 1 point).

The results showed that the emotional value of rewards retroactively enhanced memory. For instance, participants who later received high rewards after animal images recalled those animals with about 5% greater accuracy. However, the same effect did not apply to the tool images.

The study provides direct evidence for selective memory consolidation. It suggests that the brain assigns meaning to earlier ordinary experiences by linking them to subsequent important events, making them more memorable. In the future, this principle could inform therapeutic approaches—such as strengthening everyday memories before trauma to ease distress—or guide teaching strategies, where novel and engaging activities might boost students' information retention.