A classic static example demonstrates the potency of changing a surrounding color. The two orange discs are the same color, but the different surround colors "push" the orange so the they seem to have different colors. Compared to the red surround, the green hue pushes the circle to look more reddish, and the lighter value of the green pushes the circle to appear darker.
Animating this example reveals how the perceptual process behaves as an element of color-change syntax.
Here are two more examples. If you are not certain the circle color is constant, cover the surround with a card with a hole in it.
In this example the value of the surround is always higher than the object, so it relies on hue pushing only, not value pushing.
B2c) Hard and Soft Color Changes