I've heard many an experienced roleplayer talk about how it's important to keep player knowledge separate from PC knowledge. Some even seem to go as far as holding the opinion that it is part of what distinguishes a great roleplayer.
This basically boils down to pretending you don't know something, which in my mind seems somewhat at odds with 'immersion' as I understand it. So, the way I see it either the technique has some effect on immersion, or my understanding of immersion is wrong-- so I'm asking for your thoughts.
Does having to separate player knowledge from PC knowledge affect immersion for you? If so, how?