I was putting up some wall decorations earlier today and was painstakingly realigning everything until it looked level to my eyes. It might be just a hair off, but if I don’t correct it, I’ll see the misalignment almost instantly and get bothered for the rest of time until I fix it. Has anyone investigated, or is there literature on the minimum perceptible angle from level to the naked eye?
I believe it depends on the environment.
Meaning crooked walls/ceiling/floor influence what we believe is visually straight.
Yep, what we consider to be level is relative to what you use to establish an axial plane.