Arsty Fartsy Plato II: Perception

So, Plato's allegory of the cave is all about our perception of reality versus actual reality, right? Well, our discussion got me thinking about perception as it relates to art, specifically how we represent reality in art. Below I have included a photo of a still life project that the AP Art students just completed.

The assignment was to do a charcoal drawing of the still life as we perceived it. This assignment made me think of my mantra for art: draw what you see, not what you know is there. If you look at the setup for this still life, you should notice that all of its elements are white. Objectively speaking, we know they are white and could prove so scientifically if necessary. However, if we drew what we knew to be the objective "reality" of the still life, you'd get something like this:

Not all that interesting or "accurate," is it? My point in all this is that sometimes to represent our perceptions in a way we can understand it, we have to fudge reality. While each object is solidly white, it cannot be perceived by the human eye as being entirely white.

There are a few questions that I would like y'all to think about:

1) Is everyone's perception of reality the same?
2) If yes, then are all elements the same or are there just a few elements in common?