Infantile Amnesia

On my eldest daughter’s second birthday, we ferried her to one of her favorite parks. After cake, singing, and gifts at a shelter house, I took her toward the playground. When we approached the slides, a smile erupted on her face that seemed to illuminate the entire planet. It was one of the small moments of joy that can lighten even the hardest heart.

I knew I would recall that instant as long as my memory remains healthy. A small tinge of sadness filled me, as I realized my daughter would very likely not remember this day or this visit to the playground. We both experienced the happening, but, thanks to infantile amnesia, only I would maintain the recollection.

What’s your earliest memory? Most people cannot recall something happening before the age of two. For many people, the age is higher, sometimes up to seven years old. Further, even if some memories do persist from this range, they tend to be rare, garbled, or incomplete. For example, I have a distinct memory of getting on a plane with my mother as a young child but I cannot reminisce more than a fleeting impression. I don’t see the rest of the flight or trip, and I don’t have many other memories from this age.

Yet, memory does work in infants and toddlers. What causes humans to forget things that happen before a specific barrier is crossed?

My daughter has no trouble remembering the details from dozens of her favorite cartoons. She has memorized books we read at bedtime, reciting them to us. She recognizes places and faces. She knows exactly where the aquarium is in the local department store. She knows the names of all the pets that live with my parents. She knows that when it’s time to go somewhere else, she needs to put on socks and shoes.

Many of these things will likely remain within her brain as she ages. Studies have shown that infants can form memories extremely early, as young as two months. So, why can’t we remember being born? Why will specific things in my daughter’s life not reside in her memory when she’s older?

Part of the issue lies in the different types of memories. When we think about forgetting a life event, we’re referring to autobiographical or episodic memories. This designation is the type that seems to ebb as time moves forward in children. The things my daughter can recall with ease are classified differently. Semantic memories – facts and figures – and procedural memories – the required steps to achieve a task – seem to build up within a human from an early age. As adults, we might not recall the first time (an autobiographical instance) we learned to put on socks and shoes to go outside, but we have never forgotten this procedure. You might not know the moment you learned Everest is the world’s highest mountain or the capital of Djibouti is Djibouti, but you recall the semantic information.

It’s the autobiographical memory that seems to be the problem with children.

Sigmund Freud famously theorized that infantile amnesia stemmed from the trauma of childbirth and its “inappropriate” sexual nature.

This viewpoint has fallen out of favor, though scientists still do not definitively understand why childhood amnesia occurs. A few theories exist.

The most basic and oldest idea revolves around the general underdevelopment of a child’s brain. Perhaps the noggins of youngsters simply cannot generate long-term memories. Various studies seem to indicate this notion is incorrect. One experiment showed children aged 7 could recall up to 60% of their early episodic memories. The percentage for the same children at ages 8 or 9 had already dropped to 40, which seems to display infantile amnesia in motion.

Other ideas relate to the undeveloped brain in slightly different ways. Scientists know the hippocampus is crucial to the storage of memories. The brains and, therefore the constituent parts of the brains, of children are not fully formed. Perhaps the hippocampus of a child can create memories, but it’s not yet very good at doing so. Another theory relates to the genesis of neural pathways as we age. The development of new neurons in a growing brain might interfere with the trail on which an autobiographical memory was wired, perhaps mangling or deleting the memory. Some adhere to the notion that language is critical to the formation of memories, a skill lacking in children. How can one form a long-term memory if our brains lack the inner vocabulary to describe it? Yet another concept hinges on a brain fundamentally altering the way it accesses memories as we age. If the memory lived on the other side of a chasm and the brain required an airplane to reach it in childhood but the wings disappeared as we aged, perhaps we can no longer make it to that memory.

These theories are difficult to test, partially because the subjects usually lack the sophistication to help with experiments. One of these ideas could be the reason for infantile amnesia, or it could be a combination of several. Perhaps, of course, none of the above is correct.

To date, the cause of the phenomenon is unknown.

Some studies do show one aspect that might shine some light on infantile amnesia, though. What causes the few memories we do retain to stick? One attribute seems to be emotion. Episodes that elicit a high level of feeling or sentiment tend to lodge in our brains through adulthood. Physical trauma, extreme sadness, the birth of a sibling, utter joy, significant firsts. These types of memories might make it past the amnesia barrier.

Further, a sense of self seems to help, in the sense of a child and a memory forming a story. If an autobiographical moment can form a narrative in which the child plays a key role, especially an emotional one, the episode might just stick around.

Perhaps my daughter was so overwhelmed with delight when she saw the slides on the heels of an emotional birthday party that she will remember the magical moment. I suspect, though, that she’ll have a litany of wonderful and terrible moments on which to draw the lucky few that last into her adulthood. Slides and celebrations are great, but this one likely meant more to dad than to daughter. That’s okay, I can remember the moment enough for the both of us.