Original Website: http://web.mit.edu/persci/people/adelson/checkershadow_illusion.html
I didn’t believe its claim that the squares marked A and B are the same shade of gray. I printed out the image. I still didn’t believe it. I cut out the A and B squares and brought them together—they match.
Below are the two squares cut out with Microsoft paint
Since my perceptions are clearly wrong with a simple image, I don’t think I should be confident that my perceptions on other things (like people) are accurate. Clearly, when senses and human frailties are involved truth can be elusive.