So, I downloaded the picture and checked the pixel color of each square with Microsoft Paint. Easy to do, and that confirmed it. Crockford was right: my brain is definitely interpreting what it sees in light of my experience; my experience being that checker boards always have alternating colors.
This really affected me because the illusion is so persistent. Usually I can focus on an optical illusion and overcome it.
I have mulled this over a while now basically asking the question: if my mind is interpreting this picture incorrectly, what else is it interpreting incorrectly?
I would like to know how others see this picture because I have a hunch some can see it accurately depending on their level of training.
More coming up.