The word proportion refers to the size, and how different parts of a particular object work together to make that object look the way it looks. Depending on the proportions of that object, a viewer may or may not like it, based on their personal affinities.
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.
well seeing i am an artist and i actually did a self portrait; i will describe how i painted it. i used acrylic on a stretch canvas about 4 feet wide by 6 feet tall. i painted myself smiling in a soft pink long dress, white tile floor sitting on a white couch with a table behind and a vase of gorgeous flowers. i also had a round white hat with a soft pink ribbon through it laying on the floor and on the table behind me was a lit candle. i kept it simple but soft and romantic.