It’s almost impossible to believe, but square A is exactly the same shade of grey as square B. This illusion is incredibly strong. Even when you’ve seen the proof, your eyes will keep deceiving you. The illusion works for a number of reasons, for example:
- Your mind compares the checks to its neighbors. Check A is surrounded by dark checks and seems lighter.
- There seems to be a shadow on the board, and your mind assumes that an object in the shadow is darker.