Color saturation trick to boost apparent brightness

Ok, I've always heard the common wisdom, from art teachers even, that high contrast will draw the eye to a focal point, and that "the lightest light against the darkest dark" provides the greatest possible contrast. But that's bunk. Look at this chart:

Notice how much brighter the white n the center looks? And yet it's around the outside edge where you have black directly against white, so shouldn't that be the highest contrast? Nope - the illusion of glare is far more powerful than mere contrast. And it's not just the fact that the green grows gradually lighter value-wise toward the center - it's also because of the increasing color saturation (chroma). Black against white is dull - but fade that black toward ever lighter brilliant green and you get an illusion so powerful that the eyes literally contract for a while believing they're looking into a bright light. It's actually a little hard to look directly at the center, isn't it? And yet the white there is no brighter than around the outside edge.

This was posted on a thread about glowing color associated with this painting: