There is something that I like to call "The Bias of Knowing". Everything that a person thinks is biased toward what they know. When I am asked to draw something on a piece of paper I draw a dog because I know what a dog is. Maybe I draw a big scribble, but we've all seen scribbles before.

You see, our imagination is built of many parts of things that we have experienced in the past. We can never imagine something genuinely new. We can, at most, combine old things/ideas in a new way.

An interesting book looks at this fact. "Flatland: A Romance in Many Dimensions" by Edwin A. Abbott shows that a being in a two-dimensional world can never conceive of the third dimension until he actually experiences it. This makes you wonder what a fourth dimension might be... Don't bother. You're a three-dimensional being. Your thoughts are biased to three dimensions because that's what you KNOW.