Question

A reading may appear to be different when viewed with one eye or the other, or when the head is moved from side to side or up and down. This apparent measurement difference is due to a change in position of the observer, and is called?

Answer 1

Parallax correct?

Answer 2

Yes

Answer 3

actually, it's just called parallax .... but that's picky of me.
Slightly more constructively is the number of phys expts that rely on "no parallax" to line things up and locate them. Optics is pretty good in this dept. I guess for "visual reasons".
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