There's so much going on in the world at any given moment it can be hard for the brain to take in every detail. As a result, it's sometimes tough to completely miss major changes that happen right in front of our eyes.

If you're busy concentrating on one thing, you simply have to tune out huge amounts of other information that your brain cannot deal with at that time.

Expectations also can play an important role. Would you expect a person to suddenly transform into somebody else while you were talking to them? Of course not—so it's not so surprising you might miss a major shift in your situation or environment.

Metaphor:

Don´t let the schooling interfere with your education ...!!!

Amazing @chbartist ...!!!