We can’t remember being babies - but our brains might

Most people can’t recall their first steps, their first birthday, or even their first favorite toy – as if the brain somehow erased those early memories.

For decades, researchers believed this memory loss, known as “infantile amnesia,” stemmed from the underdevelopment of a key brain region. But new research from Yale University challenges that idea.

Early role of the hippocampus

Scientists at Yale University have found that even very young infants can encode memories.

The team studied babies aged four months to two years using functional magnetic resonance imaging (fMRI) to monitor their brains as they viewed new images of faces, objects, and scenes.

When infants were shown a previously seen image alongside a new one, those who had more hippocampal activity during the first viewing were more likely to look longer at the familiar image. That’s a sign the infant remembered it.

Study senior author Nick Turk-Browne is a professor of psychology in Yale’s Faculty of Arts and Sciences and director of Yale’s Wu Tsai Institute.

“The hallmark of these types of memories, which we call episodic memories, is that you can describe them to others, but that’s off the table when you’re dealing with pre-verbal infants,” said Turk-Browne.

Measuring memory in babies

Because babies can’t talk, studying their memory has always been tricky.

The team developed a test using visual recognition. Babies usually look longer at things they recognize. So, if a baby stared at a previously seen image longer than a new one, researchers took that as a sign of recognition.

“When babies have seen something just once before, we expect them to look at it more when they see it again,” said 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.”

Brain activity in the hippocampus

The study focused on the hippocampus – the area of the brain involved in memory. The researchers found that activity in the hippocampus during the initial viewing of an image predicted how well the baby would recognize it later.

The strongest activity was in the back part of the hippocampus, which in adults is associated with episodic memory – our ability to remember specific events.

The results were consistent across all 26 infants in the study, but the effect was especially strong in those over 12 months old. This supports the idea that the hippocampus gradually develops the capacity for episodic memory in the second year of life.

Two types of memory in one small brain

This isn’t the first time the Yale team has looked at memory in babies. In earlier research, the researchers showed that even three-month-old infants use a different type of memory called “statistical learning.”

While episodic memory helps us remember specific events – like a birthday party – statistical learning helps us notice patterns, such as how most birthday parties have balloons and cake.

“Statistical learning is about extracting the structure in the world around us,” said Turk-Browne.

“This is critical for the development of language, vision, concepts, and more. So it’s understandable why statistical learning may come into play earlier than episodic memory.”

These two types of memory use different areas of the hippocampus. Statistical learning happens in the front part, which develops earlier. Episodic memory relies more on the back part, which matures later.

This difference might explain why babies are good at picking up patterns even if they can’t recall specific events.

Where do those early memories go?

If babies can form episodic memories, why don’t we remember our own earliest experiences? According to Professor Turk-Browne, there are a few possible explanations.

One is that these early memories don’t stick around – they may fade before becoming part of long-term memory. Another idea is that the memories still exist but are inaccessible later in life.

In fact, the Yale team is now exploring whether memories formed in infancy can persist, even if we can’t recall them as adults.

The researchers are testing whether children can recognize home videos taken from their own perspective as babies. Early results suggest some of these memories might last into preschool years.

Tristan Yates, lead author of the current study, is a developmental cognitive neuroscientist at Colombia University who received her PhD from Yale under the guidance of Professor Turk-Browne.

“Tristan’s work in humans is remarkably compatible with recent animal evidence that infantile amnesia is a retrieval problem,” said Turk-Browne.

“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.”

A new understanding of the baby brain

This study suggests that the baby brain might be more powerful than we thought and that our earliest memories may not be completely lost. Instead, they might be stored in ways we don’t yet understand.

The hippocampus seems to be working much earlier in life than once believed, and the idea that we simply can’t retrieve those memories – rather than not forming them at all – is gaining traction.

The research opens new questions about how memory develops, how it changes over time, and whether those lost moments from our baby years are still hidden deep within us.

The study is published in the journal Science.

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