In my experience, it made it very clear how easy it is to have a disconnection between what is happening in the "real world", my perception of it and what happens in my brain.
Basically your brain is a big box of chemical reactions that happen regardless of what's going on in the world, and you unconsciously interpret the world through whatever your brain makes you feel at the moment. (For example, think about the fact that you don't notice your nose most of the time, it's there at all times but your brain filters it)