Researchers at Yale University think they may have some insights into why we don’t remember anything from when we were babies. We were certainly conscious, in the sense that we perceived the world around us. If we were not conscious, we could hardly have learned all that we had to learn in those first few months of life.

So What Was Missing?

The most widely accepted theory has been that the hippocampus of the brain, which plays an important part in memory, is not well-developed enough. But the new research, involving 26 infants of various ages, challenges that explanation for “infantile amnesia”:

For the study, the researchers wanted to identify a robust way to test infants’ episodic memories [memories of specific events]. The team, led by Tristan Yates, a graduate student at the time and now a postdoctoral researcher at Columbia University, used an approach in which they showed infants aged four months to two years an image of a new face, object, or scene. Later, after the infants had seen several other images, the researchers showed them a previously seen image next to a new one.

“When babies have seen something just once before, we expect them to look at it more when they see it again,” said [Nick] Turk-Browne. “So in this task, if an infant stares at the previously seen image more than the new one next to it, that can be interpreted as the baby recognizing it as familiar.” 

“Why don’t we remember being a baby? New study provides clues,” Medical XPress, March 20, 2025

Infants, of course, have a short attention span. Even so, the fMRI study showed that

… the greater the activity in the hippocampus when an infant was looking at a new image, the longer the infant looked at it when it reappeared later. And the posterior part of the hippocampus (the portion closer to the back of the head) where encoding activity was strongest is the same area that’s most associated with episodic memory in adults. 

“New study provides clues“

So apparently the infant hippocampus is well-developed enough to sustain some episodic memories. Why don’t they last longer?

Two Different Types of Memory

The researchers gained some more insights when they distinguished between two different types of memory: episodic memory, as tested above, and statistical memory, which means recognition of patterns. (For example, the sound of heavy footsteps means an adult is coming.)

Infants as young as three months old have been found to display statistical learning, which uses a different neuron pathway in the hippocampus from the one generally used by episodic memory. Episodic memory develops later in infancy.

As to why episodic memories from infancy fade, psychologist Nick Turk-Browne, senior author of the open access study, published in Science, offered some thoughts:

There are a few possibilities, says Turk-Browne. One is that the memories may not be converted into long-term storage and thus simply don’t last long. Another is that the memories are still there long after encoding and we just can’t access them. And Turk-Browne suspects it may be the latter. 

“New study provides clues”

Thus he doesn’t rule out the possibility that such memories still exist: “We’re working to track the durability of hippocampal memories across childhood and even beginning to entertain the radical, almost sci-fi possibility that they may endure in some form into adulthood, despite being inaccessible.”

Cross-posted at Mind Matters News.