What you remember about your life is almost certainly not accurate. Adults have very few memories before age five, and there is a systematic bias to the memories most people have for the rest of their lives. We are more likely to remember details about positive events like marriage and having children than we are to remember negative events like hospital stays or the death of a loved one.
Many studies have found that people appear to remember much more from their teens and 20s than the rest of their lives. A fifty-year-old might remember more about her 20s than her 30s, even though the events in her 30s were more recent. Is there something about the teens and 20s that make them more memorable? Or do our brains just lose the ability to form lasting memories as we age?
Systematically studying autobiographical memory is difficult because there isn’t an easy way to check and see if a reported memory is accurate. A researcher can identify a bias, but she can’t say whether the memories her subjects report are qualitatively different at different ages. I’ve written a memoir and I found that many of the things I “remembered” with utmost clarity turned out to be untrue. But it’s impractical for a researcher to fact-check the hundreds or thousands of memories she’s analyzing.
Still, studying the memories themselves — accurate or not — can tell us a lot about how memory works. A team led by Clare Rathbone asked 16 volunteers age 47-66 to report on the key memories about their lives, by coming up with 10 concepts that complete the phrase starting “I am …”. They then picked three that best defined themselves. Here are my top three: I am a writer, a father, and introspective. For each of these three statements, they were asked to generate ten specific memories of times when the statements were a significant part of their identity. So, for me, this would include when I published my first book, when I sold my business to become a full-time writer, and when I started this blog. Finally they were asked how old they were when each of those three defining statements became “a defining part of their identity.” I became a writer at age 36 when I finished my memoir, and a father at age 24. When I became introspective is a little harder to nail down. I’m going to say age 24 for that, too, because becoming a father also makes you think a lot about who you are.
What ages produced the most memories? Here are the results:
Other than finding very few memories below age 3, there’s no clear pattern to the results, and certainly no “bump” between the ages of 10 and 30, as earlier researchers had found. Indeed, there hardly appears to be any pattern to the results at all. But perhaps they were just looking at the data the wrong way. This graph takes a different view of the data, from the perspective of the identity-defining events:
So the year when each “self” (“father,” “writer,” “introspective”) is formed counts as 0 on this graph, which then charts how many memories from all respondents occurred on each year before and after the defining event. These memories are most likely to occur within a few years of the event itself. They’re also skewed to the right, meaning there are more memories of events after the identity-forming event than before. (Obviously this makes a lot of sense for events like having a child or getting married).
Even more interesting is what happens when we look at the years when identity-forming events occur:
The green columns show the years when respondents point to self-identity-defining moments (this is actually data from a second, larger online study). The most common years are between ages 11 and 30. The orange columns then compile data for only the first three memories respondents identified for each self. These memories peak in the 20s and 30s — a very similar pattern to the “bump” identified by earlier researchers.
Rathbone’s team believes this demonstrates that identity-forming events are what shape the biases in autobiographical memory: We remember more details about certain things because we now believe those things define who we are. The reason earlier researchers found general memory bump between 11 and 30 is because that happens to be when most of us experience the most significant events in our lives: the start of careers, marriage, and families.
This corresponds well to other researchers who have found that immigrants remember more details about the years surrounding their time of immigration than non-immigrants. So if you immigrate in your 30s, you’re more likely to have memories from your 30s than someone who immigrated in her 20s. Other studies have found a memory bump in people from Bangladesh corresponding to a period of political unrest in that country. So it seems that our memories are affected more by the events in our lives than just the physical development of our brains. We’re not all destined to remember more of our teens and 20s than other years; we’re just more likely to experience significant, life-changing events in those years than others.
C. J. Rathbone, C. J. A. Moulin, M. A. Conway (2008). Self-centered memories: The reminiscence bump and the self Memory & Cognition, 36 (8), 1403-1414 DOI: 10.3758/mc.36.8.1403