One of the great mysteries of psychology: we learn incredibly quickly as babies, yet we later have no conscious memories of that period. This phenomenon is called infantile amnesia. For a long time, it was thought that it was simply because a baby’s brain, specifically, the hippocampus, wasn’t yet mature enough to store memories truly.

A recent study in Science puts that picture into perspective. Researchers from Yale and Columbia scanned the brains of awake babies while they were briefly shown photographs. Afterwards, they tested whether the babies showed a preference for recognising previously shown images. And guess what? From about one year old, the scientists observed apparent activity in the hippocampus for images that the children later recognised. In other words, the brain can already encode individual memories during the first year of life.

This could lead to a significant shift in our thinking. It increasingly appears that the problem lies not so much in storage, but in retrieving them later. The memories may be present, but they are deeply buried and not spontaneously accessible. Interestingly, these results align with research in mice, where memories from infancy can also be retrieved through artificial stimulation.

For parents hoping their child will later remember their first birthday cake or a seaside vacation, this might be disappointing. But scientifically, it’s good news: it opens up new questions about how memories develop and why some are preserved and others aren’t.

The study also shows that memory develops gradually. Babies younger than 9 months had not yet shown this effect. This aligns with behavioural studies that have long demonstrated that around the first year of life, there’s a leap in how children make connections and remember experiences.

In short, infantile amnesia isn’t a matter of a dysfunctional memory, but rather of inaccessible memories. Perhaps we all carry more baggage from our infancy than we’ll ever consciously realise.

Abstract of the research:

Humans lack memories for specific events from the first few years of life. We investigated the mechanistic basis of this infantile amnesia by scanning the brains of awake infants with functional magnetic resonance imaging while they performed a subsequent memory task. Greater activity in the hippocampus during the viewing of previously unseen photographs was related to later memory-based looking behavior beginning around 1 year of age, suggesting that the capacity to encode individual memories comes online during infancy. The availability of encoding mechanisms for episodic memory during a period of human life that is later lost from our autobiographical record implies that postencoding mechanisms, whereby memories from infancy become inaccessible for retrieval, may be more responsible for infantile amnesia.