Most of your memories come from a ten-year window.

Ask a seventy-year-old to tell you the memories of their life — not the important ones, just whatever surfaces — and you might expect the count to fade smoothly with time: lots from last year, fewer from a decade ago, almost nothing from the distant past. Two of those guesses are right. There are plenty of recent memories. There is near-total darkness over the first few years of life. But between them sits something nobody predicts until they see it: a hump. A thick surplus of memories from roughly ages ten to thirty — often the late teens and early twenties most of all — that stand out against everything before and after.

Psychologists have measured this so many times it has a name: the reminiscence bump. It shows up whether you cue people with random words, ask for their most vivid memories, or ask which songs and films were “the best.” It shows up across cultures, with the exact peak shifting a little. It is one of the most reliable shapes in the study of autobiographical memory — and it means your life, as stored, is not a flat timeline. It’s front-loaded onto one decade you mostly weren’t paying attention to at the time.

Why that decade? There isn’t one settled answer — hold all of these loosely — but three accounts keep earning their place, and they’re not really rivals.

The cognitive account points at novelty. Your teens and twenties are dense with genuine first-times: first love, leaving home, the first real friends you chose rather than inherited, the first work that felt like yours. First-times encode deeply and get distinctive retrieval routes, and they happen against a stable-enough backdrop that each one stands apart. Later, life becomes variations on themes you already have — and variations blur.

The identity account points at the self. That window is when most people assemble who they are, and memories laid down while the self is forming become self-defining. You rehearse them, tell them, build a narrative around them — and rehearsed memories survive. They’re not just in the story of you; they’re load-bearing.

The cultural life-script account is the sly one. Every culture carries an expected schedule of a life — the milestones a life is “supposed” to contain, and when. Most of them are penciled into that same decade. So when you go looking for your memories, you may be partly reading them off a template the culture handed you, retrieving the events the script says should be there. Some of the bump might be less a fact about your brain than a shape your culture pressed into it.

Here’s the quietly unsettling part. That certainty that the music of your youth was simply better, that the world was more vivid then, that things meant more — it’s at least partly a retrieval artifact. Not a verdict on the era. The era got the good encoding slots because you were young and everything was new, and your memory has been quietly overweighting it ever since, presenting the accident of when as a judgment about what.

Which suggests something almost usable, if you’re past that window and wish life still printed itself that vividly: novelty is the encoder. The reason a single trip to somewhere unfamiliar can feel longer and stick harder than three ordinary months is the same reason the bump exists. Break the variations-on-a-theme. Do first-times on purpose. You can’t relive the decade — but you can keep giving your memory the kind of material it decided, long ago, was worth keeping.

The science, to look up: the reminiscence bump — Rubin, Wetzler & Nebes (1986); a good modern review in Koppel & Rubin, Current Directions in Psychological Science (2016); the cultural life-script account in Berntsen & Rubin (2004); and a PLOS ONE systematic review (2018). The size and peak of the bump shift with how you ask (word-cued vs. important vs. favorite memories) and with culture, and the mechanisms are still debated — so take the shape as robust and the explanations as live questions.