The foundation of Developmental Psychology was formulated by a Swiss psychologist named Jean Piaget.
Children develop cognitive (thinking) skills in a certain order, and very roughly, at approximately the same ages. For example, concepts like addition are typically learned before subtraction. Further, addition and subtraction are learned before multiplication and division. Multiplication and division are learned before fractions....and so on.
A master storyteller
One reason that Paiget is recognized as the father of Developmental Psychology is because he left behind a collection of personal stories that he told in a compelling manner.
One of his stories regarded the inherent unreliability of eye witnesses. He had vivid memories of his nanny fending off a mugger/kidnapper in a park. Paiget could describe the mugger in graphic detail, down to the color and swoop of his mustache.
Decades later, when the nanny retired, she admitted that there had been no mugger. Rather, she had a tryst with a man-friend in the park and things got, well, a little bit physical. Her uniform had been torn during the passion and she needed a story that would not get her fired.
She told little Jean that she had fearlessly fended an evil man who had intentions of purloining the young lad from her care. Little Jean attached the dasterdly act to some man he had seem, one who appeared sinister and disreputable in his four year old eyes.
Not-so-little Jean was stunned. He had very clear memories of seeing his fearless nanny ferociously fight off the heinous villain. What is notable about Jean Paiget is that he did not dig a deep hole and bury the story. He reported it as a psychological phenomena that might be worthy of study.
We now know that phantom memories are common.
Hold that in buffer...waiting....waiting...waiting
One of his studies involved attempts to identify the age that children develop the abstract reasoning ability. He chose the ability to see and replicate patterns...a precursor to word recognition. He showed simple patterns of sticks like long-short-long-short... or long-short-short-long-short-short-long...to the child and then asked the child to replicate it.
To eliminate spurious variables he tracked the same bunch of subjects and tested them every six months or so. One test period they were not able to do it. The next test period he was slightly delayed, came into the test area and saw the children playing with the sticks. They were replicating the patterns he had shown them six months before. Six months is a huge percentage of a 3 1/2 year old child's life.
This was a stunning find. The kids had been walking around with mental pictures of these patterns of sticks in their heads. And then the last few neurons clicked into place and they could do it...without a refresher session.
A little knowledge is a dangerous thing.
There is a powerful temptation to overestimate the potential of "buffer".
The native programming language of our brains is emotional, analog, spacial-sensory. Being able to re-find seasonal food sources via memory maps and recognizing edible species via "patterns" kept our species alive for many millennia of prehistory. The patterns of sticks are spacial and our brains are hardwired to accept that kind of information.
Digital/abstract/statistical is an alien operating system floating on top of our native operating system. As an alien system the information is volatile because the packet of information do not easily wedge our brain's cubby-holes. We can remember this stuff but it is energy intensive. We must keep accessing the information to refresh it.
That is why one cannot teach the chain rule of differential calculus or indicial notation in third grade and expect it to "click into place" in college. The volatility factor means that information will have burned off as the child has no need to ever use that digital/abstract/statistical information.
The human brain has the ability to re-wire. My kids are amazed at my ability to remember strings of seven digit numbers. They think it is unworldy. We used to call strings of seven digit numbers "phone numbers". My kids call them contacts and have no need to remember them. I bet that most kids cannot even recall their mother's cell number.
Even with neural rewiring there is still an energy requirement for maintenance. It is simply lower than before rewiring.