My toddler’s train track is freaking me out right now. What is going on here?! pic.twitter.com/9o8bVWF5KO
— marc blank-settle (@MarcSettle) April 6, 2016
BBC Academy trainer Marc Blank-Settle discovered that two identical pieces of his toddler’s toy train set could be used to create a baffling optical illusion. Although they are the same size, when one piece is placed above the other and the left edges are aligned, the bottom piece appears larger.
This is known as the Jastrow illusion, and it is due to the fact that the outside arc of both pieces is larger than the inside arc, and because the left edges of the pieces are aligned, offsetting the bottom the piece.