Do you remember taking your first steps? How about saying your first words? How well can you retell the events of your first day of daycare? What was the first joke you laughed at? Most adults can’t answer these questions and even if they can, they can’t answer it with 100% confidence that their memory of those events is actually accurate. We have a hard time remembering our earliest memories because of something called infantile amnesia. This is when people over the age of seven have trouble recalling events from early childhood. Our bodies and brains develop the most during childhood, which also includes our memory-forming systems in the brain. So since we’re still learning to form new memories when we create these memories, it’s hard for us to retrieve those memories as adults.
Travaglia et al (2016) did a study focusing on infantile amnesia and found that it is strongly connected to the development of the hippocampus. The hippocampus is a brain structure in the temporal lobe that is associated with learning and memory. Other researchers found strong connections between the hippocampus and long term memory. (Katzman, 2022) As a result of all of the development happening in the brain at the time, our hippocampus is not fully functioning as it would in an adult.
Even though you can’t answer the questions from the beginning, is there a place from your childhood that you used to go to that feels familiar or like home to you? Is there a song you were told you listened to as a kid that gives you a warm feeling? Have you ever looked at a picture from your childhood and been able to remember exactly how you were feeling in that moment? It is important to realize that even though infants and toddlers do not have a fully-functioning hippocampus, it is still functioning and forming memories to a certain extent. This is why you can see the effects of childhood memories on grown adults. An infant can go through trauma and be affected by it in their later years. This is also why parenting styles early on in a child’s life can have a huge impact. You may not be able to say the memories but their memories are still there influencing your behaviors in the same way other memories do.
This phenomenon can be explained by a problem with retrieval of a memory in infants and toddlers. It seems like at the time, they are able to store the memory but having trouble retrieving it. This would explain why even as adults, we can’t seem to retrieve the memory but it still intuitively effects our behavior because the memory was somehow stored.
Research done a few years ago provided a demonstration of this problem with retrieval in baby rats(Travaglia, et. al, 2016). Travalgia and colleagues did a study on rats that proved an experience from early childhood was stored as a memory trace. The researchers used 17-24 day old rats and tested the likelihood that the rats would return to an area in which they were previously shocked. There were two compartments and a door separating both compartments. The first compartment is where the rat is initially placed. When the rat enters the second compartment, the door is closed and the rat is shocked on the foot. They are then tested later to see whether the rats will enter the second compartment. Some rats were trained to remember the shocking while other rats only experienced the shocking experience one time and other rats (the control) did not experience the foot shock at all.
They found that when the rats were trained to remember there was a shock, they would remember not to go into the second compartment but would rapidly forget (about 1 day later). They also tested whether a contextual reminder or a shock-reminder would reinstate the memory. While the contextual reminder did not, when the rats were shocked again, it reinstated the memory. They had similar results to how they acted right after they were trained. The rats being able to learn and avoid the shock initially shows they stored the information somehow. However, they were unable to retrieve that information later and weren’t able to use it to avoid the shock then. While there are differences between rats and humans that could change how this can be applied to us, we see parts of this study a lot in toddlers without even realizing it. Toddlers can hurt themselves running around and cry about it. However, not even minutes later, they can be up and running again, doing exactly the thing that caused them to get hurt.
Infantile amnesia is a very interesting concept because it’s happens to everyone. As a result, it gives us a lot of information about our development, how memories function in childhood and adulthood, and how these memories can affect our lives.
- Alberini, C. M., & Travaglia, A. (2017). Infantile amnesia: A critical period of learning to learn and remember. The Journal of Neuroscience, 37(24), 5783–5795. https://doi.org/10.1523/JNEUROSCI.0324-17.2017
- Katzman, A. C. (2022). Molecular mechanisms of memory consolidation and enhancement in the prelimbic cortex and dorsal hippocampus [ProQuest Information & Learning]. In Dissertation Abstracts International Section A: Humanities and Social Sciences (Vol. 83, Issue 2–A).
- Li, S., Callaghan, B. L., & Richardson, R. (2014). Infantile amnesia: Forgotten but not gone. Learning & Memory, 21(3), 135–139. https://doi.org/10.1101/lm.031096.113
- Travaglia, A., Bisaz, R., Sweet, E. S., Blitzer, R. D., & Alberini, C. M. (2016). Infantile amnesia reflects a developmental critical period for hippocampal learning. Nature Neuroscience, 19(9), 1225–1233. https://doi-org.colby.idm.oclc.org/10.1038/nn.4348