My earliest clear memory is that of my 4th birthday, from the moment I woke up to a couple of hours later. I remember my mom telling me to get dressed up so we can go to the daycare and after to school, which I started to do and then thought “what’s school? what’s daycare?” (these I asked) “why are you my mom?” (this one I didn’t for some reason). After being fully dressed, we got into the car and drove to the daycare, I was guided to a room that’s next to the kitchen and told to wait. A couple of minutes later, I notice a light coming from the hallway connecting to the kitchen (“what’s that? why is it coming closer?”), then the nanny, her husband and my mom come out with a cake. I then immediately asked why there was a cake, I was told it’s my birthday, and then I asked what’s a birthday.
So yeah I think kids ask a lot of questions the moment or around when they start to be self-aware.
So would the fact that most people start remembering stuff from then more vividly be more of a coincidence?
It’s probably more related to how the hardware stores the software; the strength of a memory depends on the strength (complexity) in the interconnectivity of neurons related to that memory. The more some piece of information relates to other information, the physically stronger the connection of neurons that make up that information become.
Prior to 3ish our brains are focused on the foundations needed to form complex thought and memories; sensory perception, coordination, time, language, etc. Once we reach a certain level of skill with those foundations we probably hit a threshold where new pathways are strong/complex/interconnected enough to last, and be continually reinforced or built upon, for a lifetime, to the extend they are unlikely to ever deteriorate without some TBI or neurodegenerative disease.
NOTE: not a doctor.