Question

the size relationships between parts of an object, or its ________________, affects how a viewer will interpret it.

Answer 1

I believe the answer is: proportions

If one part of the object made in larger proportions relative to other parts, most of the attention that given by the viewer would be focused on that part.

For example let's say that you see a black shilloute of a cube. Without additional detail viewers would perceive this simply as a cube.

But, if you put a shilloute of a human that has smaller proportion compared to the cube, viewers would perceive the cube as a giant building.

Answer 2

The size relationships between parts of an object, or its relation to another object, affects how a viewer will interpret it. Each person will have his own perception of the object depending on how he sees it. This is true for all since each one of us sees thing differently. Hope this answers the question.