What Is Infantile Amnesia?

Medically Reviewed by Renee A. Alli, MD on July 21, 2024
Written by Alyssa Anderson
5 min read

Infantile amnesia is a version of amnesia that seems to be a side effect of your brain’s normal developmental processes. As a result, almost all people have trouble remembering any biographical events before the age of four years old. 

The rate of memory also remains lower than expected up until sometime between the ages of seven and ten years old, so it’s commonly referred to as childhood amnesia. 

The exact cause of infantile amnesia remains a heavily debated issue in modern neuroscience. 

Almost every adult studied to date has infantile amnesia. Infantile amnesia best explains why we have so few early memories compared to our later childhood, teenage years, and beyond. 

The few rare exceptions tend to occur in people that store memories unusually even when they’re adults. There’s even evidence of parallels to infantile amnesia in other mammalian species — like rats. 

There are a few questions raised by this condition, and some are more easily solved than others.    

The first discrepancy is that — based on the rate that adults forget memories — humans have too few memories from early childhood. In support of this, newer research that actually involves children seems to clearly show that they forget at a much faster rate than adults. A follow-up question is why and how this is the case. 

The second discrepancy concerns how childhood memories — which we can no longer recall or discuss — can still have large impacts on your adult psychology. 

Studies have shown that events like abuse, trauma, and neglect — even when they occur in the time frames encompassed by infantile amnesia — can predispose adults to a number of psychopathologies. Examples include: 

Data from neglected children show that they almost all have problems with learning and other cognitive functions. Some of these abilities can improve with proper care, but others never recover from childhood problems. 

So, how can events that we can no longer consciously remember or articulate have such large impacts on our continued development? What is happening in our brains during the ages when infantile amnesia is most prevalent? 

These are just some of the questions that researchers are trying to solve today.   

In order to understand the potential causes of infantile amnesia, it’s important to know how your brain handles new memories. There are four basic steps to creating and accessing a new memory. These involve: 

  • Encoding information. First, your brain forms a series of connections to represent new information. These can be linked to other information that is already stored in your memory. Oftentimes, you need to be paying attention to adequately store this information. 
  • Consolidation. This step ensures that the encoded information is preserved in your brain for the short or long term. 
  • Storage. Your brain then holds onto your consolidated memories for later use.
  • Retrieval. Your brain either recreates or reactivates the original connections in order to consciously remember the encoded information. 

Keep in mind that these descriptions are highly simplified. Each one of these steps is a complex process that isn’t fully understood, but we do know that these processes are likely not fully developed in infants and young children. This lack of development is possibly related to how and why infantile amnesia occurs.

Humans make a number of different kinds of memories. Certain ones are more affected by infantile amnesia than others. 

Two broad categories of memories include declarative or explicit memories and non-declarative or implicit memories. 

Declarative memories are ones that you can consciously recall and discuss. They include episodic memories about different people, events, times, and places. They also include semantic memories, which are more general things you’ve learned about the world.

These are different from implicit memories, which are more ingrained and less accessible to your conscious mind. Examples include the knowledge of how to walk or ride a bike. 

All forms of amnesia affect declarative memories, not non-declarative ones. Infantile amnesia specifically involves these autobiographical memories — the same types that are lost in cases of Alzheimer’s and other age-related memory disorders.   

At present, no one knows the exact cause of infantile amnesia. A leading hypothesis is that it’s a consequence of the particular way that our brains develop. 

The part of your brain called the hippocampus is most likely involved in this process. It helps create the autobiographical memories that are missing in cases of infantile amnesia. Studies have shown that the hippocampus only reaches some degree of maturity when you’re between 20 and 24 months of age. It’s almost fully formed, though, by the age of five. 

This developmental timeline happens to coincide nicely with the ages that are most affected by infantile amnesia. 

Another question is whether or not this amnesia is a problem with learning and forming memories or storing and retrieving them properly. Most experts agree that even very young infants can learn and form autobiographical memories even before they can talk. 

For example, a study done at Yale showed infants two sets of images. One set contained a coherent story, and the others were completely random. The babies responded much more to the first set than the second set. Other studies have shown that infants can imitate sequences of actions that they’ve just watched. 

Additionally, very young children can remember autobiographical events that occurred up to six months ago — even when they’ve just learned to talk. 

All of this implies that children are capable of storing some autobiographical memories, so they must forget them at a much faster rate. 

The next question is if these memories are forgotten because of improper storage or problems with retrieval. More research is needed to answer this question. 

One theory is that infantile amnesia is a consequence of the hippocampus learning how to remember. It’s starting to do all of the right memory creation processes — encoding, storage, retrieval — but can’t do them as well as it can when you’re an adult. 

Since research is ongoing, there’s likely to be more data soon that can shed light on the exact causes of infantile amnesia.   

Infantile amnesia is the only type of amnesia that’s a normal part of human development. All other types are caused by trauma, injury, or systemic illness. 

In general, there are two broad categories of amnesia. Retrograde amnesia is diagnosed when you can no longer recall information from the past. All infantile amnesia is a form of retrograde amnesia. Anterograde amnesia occurs when you can no longer form new memories.