Bomboy - Using Optical Illusions to Become a Better Digital Artist

I read an article on optical illusions and the author kept making the point that our brains, after seeing a 2D piece of art, isn't looking at that object in reality; instead, you're looking at something that generates visual signals that are similar to what our brains associate with the actual object. Art is, therefore, an illusion.
What can we learn from optical illusions?
First, the brain uses an "autocomplete" function that can either fill in something that isn't there and we expect, or show us something that we know from reality. This suggests that drawing, and each line, isn't what your drawing, but just reminds you of something. I'll provide an example to emphasize this thought:

See this image? Tell me what it is. If you answered "oh, it's a house," you're wrong. Same with "it's a drawing of a house." No, instead, it is pencil on a piece of paper. It is not a house. You can't live in it, it isn't 3D, etc. It's just lines on a page that remind you of a house.
This concept was introduced to me in 11th grade IB English, and it fascinated me to also find something similar in an article.
Knowing that the autocomplete function is an ability, it is suggested to draw from general to specific. The first lines will remind you of something, and you can continue from there, making the drawing more precise to the real thing (however, as discussed before, it is never the real thing (talk about postmodernism)).
Second, brightness brings form. We use light to determine depth and whether or not an object is 3D. That is why a more realistic cube has shaded in sides--it is the emulation of light and realism. Therefore, a suggestion while drawing is to assign a light source.
Third, brightness is relative. Again, here is a picture to show what I mean:

The squares in the middle of both images are actually the same color. It is the differing amount of light around them that make us perceive them as different colors. Knowing this helps with contrast in your images (do not just have the extremes of black and white--have colors in between).
These are just some of the ways understanding optical illusions can help you MAKE a viewer see exactly what they want you want them to see. There are many other types of illusions, but these are the beginnings.