What’s your earliest memory? Statistically speaking, it’s likely from when you were two-and-a-half years old, according to a new study.

Up to now, it was believed that people generally form their earliest long-term memories around the age of three-and-a-half. This initial “childhood amnesia” is, to the best of our knowledge, caused by an overload of the hippocampus, an area heavily involved in the formation and retention of long-term memory, in the infant brain.

However, new research is pushing that timeline back by a whole year — it’s just that we don’t usually realize we have these memories, for the most part.

There, but fuzzy

“When one’s earliest memory occurs, it is a moving target rather than being a single static memory,” explains lead author and childhood amnesia expert Dr. Carole Peterson, from the Memorial University of Newfoundland.

“Thus, what many people provide when asked for their earliest memory is not a boundary or watershed beginning, before which there are no memories. Rather, there seems to be a pool of potential memories from which both adults and children sample. And, we believe people remember a lot from age two that they don’t realize they do.”

Dr. Peterson explains that remembering early memories is like “priming a pump”: asking an individual to remember their earliest memory, and then asking them for more, generally allows them to recall even earlier events than initially offered, even things that happened a year before their ‘first’ memory. Secondly, she adds, the team has documented a tendency among people to “systematically misdate” their memories, typically by believing they were older during certain events than they really were.

For this study, she reviewed 10 of her research articles on childhood amnesia along with both published and unpublished data from her lab gathered since 1999. All in all, this included 992 participants, with the memories of 697 of them also being compared to the recollections of their parents. This dataset heavily suggests that people tend to overestimate how old they were at the time of their first memories — as confirmed by their parents.

This isn’t to say that our memories aren’t reliable. Peterson did find evidence that, for example, children interviewed after two and eight years had passed since their earliest memory were still able to recall the events reliably, but tended to give a later age when they occurred in subsequent interviews. This, she believes, comes down to a phenomenon called ‘telescoping’.

“Eight years later many believed they were a full year older. So, the children, as they age, keep moving how old they thought they were at the time of those early memories,” says Dr. Peterson. “When you look at things that happened long ago, it’s like looking through a lens. The more remote a memory is, the telescoping effect makes you see it as closer. It turns out they move their earliest memory forward a year to about three and a half years of age. But we found that when the child or adult is remembering events from age four and up, this doesn’t happen.”

By comparing the information provided by participants with that provided by their parents, Dr. Peterson found that people likely remember much earlier into their childhood than they think they do. Those memories are also accessible, generally, with a little help. “When you look at one study, sometimes things don’t become clear, but when you start putting together study after study and they all come up with the same conclusions, it becomes pretty convincing,” she adds, admitting that this lack of hard data is quite a serious limitation on her work.

According to her, all research in this field suffers from the same lack of hard, verifiable data. Going forward, she recommends that research into childhood amnesia needs verifiable proof — either in the shape of independently confirmed memories or through documented external dates against which memories can be compared — as this would prevent errors from both participants and their parents, thus improving the reliability of the results.

The paper “What is your earliest memory? It depends” has been published in the journal Memory.