You may remember all those books, we used to read in childhood. One of them was about common spelling mistakes.
As a child, I never had problems with spellings. I saw a word, memorized it and never committed mistakes while spelling it. I wondered what was the necessity of such books if I never committed mistakes. Till now.
I realized that the authors of those books were adults - not kids (how could adults know what were the common spelling mistakes done by kids?). And, it was not so long for me to reach the conclusion that it is the adults who committed those mistakes, they are teaching the kids not to do.
I can safely say that I am an adult. I was born in 1994. And, I commit spelling mistakes while writing - frighteningly close to all those given in the books. I should thank Google search and automatic spell-checkers for saving me from embarrassment. If you're wondering about which words am I talking about, here they are - achieve, receive, there, their, embarrassment, commitment and so on.
Now, when I reached that conclusion, I thought about why I was committing mistakes now when I was a spelling pro as a child.
I think it has something to do with how our brains process information. As children, our neurons were not overloaded with tons of information. We were new to world and were learning about our surroundings. Getting new information and storing/retrieving it was a fairly easy task. But, things changed as we grew. Our brains have soaked in years of articles, images, movies and sounds. It is natural that we sometimes commit mistakes in the most basic of tasks such as spelling.
P.S: I am no neuroscientist. I came up with a possible explanation. If you think it is incorrect, then do inform me.