I’ve experienced how people’s attention and focus can be altered and sometimes not be focused at all. I believe it mainly depends on what your mind is focused on and where your mentality is at the moment. My friends were actually an example to this statement about 5 days ago their classes ended at the same time as mine so we agreed to meet each other after classes and i gave them a specific location of where to meet up. I gave them specific directions and they both walked past me and didn’t even recognize me , i even walked behind them and they still didn’t realize i was there . Both of my friends we’re so focused on the location given they weren’t attentive to their surroundings. I’ve experienced myself as well it actually happened today which reminded me that i had to write this but instead of a person it was an object. I was walking on to the train and I turned to me left and recognized there wasn’t a seat towards the corner only one parallel to it and when i sat down on the other side of the train i looked to my left and where i thought there was no seat there was actually a single seat. I put an image of two seats in my head and that’s what I expected to see so when i looked in that direction i didn’t see two seats so I disregarded the fact that there could potentially be one seat.