@ysmina- You do realize that perception blindness happens to everyone right? It's not just you and it has to do with your brain being overloaded with information.
The next time it happens, ask yourself if you have a lot on your mind or if you are trying to do two things at once. More than likely, you are. It is really multi-tasking that causes perception blindness. Multi-tasking has become a desirable characteristic now and people proudly claim it on job applications. But multi-tasking just means that the brain is switching between different information quickly, and not focusing well enough on either.
That's why we see but don't really see at times.