Adelson's Checker-Shadow Illusion
Would you believe that squares A and B in the above image are the exact same color? As incredible as it may seem, they are identical. Below is the same image with everything but those squares removed. Now it's apparent that they are the exact same color.
What's going on? Your brain sees that the green cylinder is casting a shadow over square B, and it knows that a shadow makes an object appear darker than it really is. So it interprets square B to be a lighter color than it sees. But the graphic is cleverly designed so that the shadow does not actually overlay square B. So your brain shouldn't make this internal color adjustment. And even though this is now explained to you, you simple can't force your mind to not do the adjustment. It's your brain's story, and it's sticking to it :-)
This famous illusion was created in 1995 by Edward H. Adelson, a professor of vision science at MIT.
Jacob Teitelbaum, M.D. is one of the world's leading integrative medical authorities on fibromyalgia and chronic fatigue. He is the lead author of eight research studies on their effective treatments, and has published numerous health & wellness books, including the bestseller on fibromyalgia From Fatigued to Fantastic! and The Fatigue and Fibromyalgia Solution. His newest book (June 10, 2024) is You Can Heal From Long COVID. Dr. Teitelbaum is one of the most frequently quoted fibromyalgia experts in the world and appears often as a guest on news and talk shows nationwide including Good Morning America, The Dr. Oz Show, Oprah & Friends, CNN, and Fox News Health.
