The simple fact is that your brain had not yet developed the ability to compound and store those memories efficiently. The neurones, while present, were still growing connections and developing.
First up, let’s understand the anatomy of the brain.
The brain is at its simplest level a collection of neurones, that contributes significantly to behavior and is thought to be the centre of consciousness. There are over 100 billion neurones in the brain, and they communicate by electrical impulses called action potentials. The connections between these neurones, called synapses, are not static. They are termed “plastic” because they change and grow over time. The brain is effectively capable of being “rearranged” because of this, and this fact is a fundamental pivot upon which this question lies.
Now let’s talk about what memory is
Memory is still not completely understood as a concrete concept, but its existence and its functioning have been well studied. “Memory is the term given to the structures and processes involved in the storage and subsequent retrieval of information.” – Simply Psychology.
We understand that sensory inputs (touch, smell, sound, sight, taste) are translated into memories (called encoding), and then stored either in long term, or short term memory. Retrieval occurs when we recall a memory. Furthermore, memories are commonly classified as either Semantic (factual, like your name and birthdate) or Episodic (eventful, like the best birthday party you ever had).
That being said, how does the loss of childhood memories, or by its official term, Infantile amnesia come about?
Well, there are quite a few contributing factors that make memory storage and retrieval near-impossible for infants; there is no definite concrete reason, but there are lots of presumptions based on research.
1. The brain substrates are not nearly developed enough
specifically, the prefrontal cortex and hippocampus which are both immature at birth, are critical in encoding memories. We are simply not biologically equipped to store memories in the first few years of life.
2. The sense of “cognitive self” has not yet developed
that is, a child is not yet entirely self-aware, and cannot necessarily “think” to itself, to say things like “remember that time when…” It’s similar to watching a cat interact with a mirror ( Dramatic cat and a mirror ); it takes a while before many animals can acknowledge the existence of self, and interact with said existence. “You can’t remember that a particular event happened to you unless you have a sense of yourself and how you exist in time” (Fivush & Nelson, 2004).
3. There is no mastery of language
Children, particularly infants, are still mastering basic language skills and heuristic understanding of the world. People who claim to have memories of “dark and wet” in the womb cannot possibly have such a thing, because the words “dark and wet”, were not yet heuristic constructs by which sensory inputs are encoded. So yes, you definitely did experience dark and wet, but without knowing what dark and wet is, it’s not necessarily possible that your brain could (1) encode the experience of such an environment or (2) recall it. It’s like storing a random file on your computer with no name, no labels, no information and no content. How are you supposed to interpret it when you retrieve it (if ever)?
4. Other cognitive principles are undeveloped
there are several other cognitive learning stages that need to be reached before solid memory encoding and retrieval can occur, such as object permanence (pay attention to this one; it’s nearly impossible to have non-instinct based interactions if you don’t understand object permanence), self-concept, theory of mind, language, and operative/working memory.
So how does one remember their first birthday?!
Frankly, forms of memory failure are to blame (in the subject and in the observers).
Source amnesia – remembering an episodic memory but misattributing where it comes from. A simple example is that you heard about a baby, or saw a movie about a baby, or maybe even saw a baby yourself, and attributed the memory to your own experience. Source amnesia is a good memory gone bad.
False memory – the belief that an episodic memory that never happened actually happened. This is very closely related to source amnesia, but, in this case, the “memory” never actually happened; it was completely made up and there is no evidence for it whatsoever. It’s been shown in multiple studies that it’s possible to make people believe they have a very vivid and clear memory of an event that never actually happened (Lost in the mall technique ). False memories are a very serious issue, especially in forensic psychology. People have been tried for crimes they didn’t commit, and witnesses have been known to identify very many incorrect suspects regularly (People Can Be Convinced They Committed a Crime That Never Happened). The extremely vivid and concise detail some people can confess to is shocking, and thoroughly convincing for them and others, but, unfortunately, the research has shown that it can often be completely untrue.
Long story short, you can’t trust your memories. People (such as your family members) around you will regularly confirm stuff for you that actually isn’t true. But most importantly, even your own brain can be a complete douche sometimes.