As an addendum, when I calculate variations in chess or Go I sometimes close my eyes because my "board database access" can be easier to operate when everything

As an addendum, when I calculate variations in chess or Go I sometimes close my eyes because my "board database access" can be easier to operate when everything is purely in my head, as opposed to performing mental diffs on the physical board in front of me, which requires me to keep track of both real and virtual pieces.