That is that the first lessons you have taken or the first lesson you have given affect the individual very deeply.
A human being is a wonderful composite of spirit, mind and body.
The mind is not only a communication system, but it also records every experience in life. When you have an experience in a whole new field the mind lodges it into a new compartment.
You may relate this new area to a bigger compartment, like sports, or game, or physical activity. But if you (the real you, the spirit) are really interested, you may have decided the “tip” could be of benefit for your survival, and so you approach it with more care, more importance.
This is where conventional tennis teaching, the “norm” for tennis starters, is at fault in the US. It instals, as first thing, an unnatural closed stance that makes tennis easier “linear” than pulling across.
No matter how much you fight this in later sessions, the earlier teaching weighs somewhat heavier in your future. The same could happen if you are taught this misconception at some point during you tennis career, and you really believed it at that time perhaps out of respect to the “pro” who delivered it.
It can affect even the performance of the best players in the world.
Not to make this tip here too long, if you want to know more about this phenomena go to one of my older books (1992), to read for FREE this and several more misconceptions: