This is a natural phenomenon of our eyes. The background, or context of a color, affects how we see it. What the evolutionary traits of this are, I have no idea, but we’ve learned in the class how a painter can use these phenomenon to create luminosity– vibrancy among colors.
The homework in the previous exercise was to make 4 different colors look as if there were only 3. The effect is not based on any tricks, if anything it is simply the illusion created by the natural state of our eyes. Our eyes are constantly adjusting not just to the light in a room but as well to the variance of color.
Impressionist painters used a similar effect in their work.
These insights on color have profoundly affected my own work.