system
A chat on 4chan
human
It would be confusing as hell unless our minds got an upgrade to process 4 dimensional space.
gpt
You wouldn't be able to perceive the extra dimension at all, except in cases where the events on the other world lines are so powerful that they creep through the bandpass filter you perceive the world through, like a stronger radio station might be able to overpower a weaker station you're tuned next to it. Without altering your cognitive abilities you are not able to affect the tuning, either, at least not consciously, but it might move if you get 'knocked' hard enough and then it sure gets confusing.