Jastrow Illusion

Curved elements are tricky. The lower arch appears to be larger than the one above, but your eyes may deceive you. This phenomenon is named after the American psychologist Joseph Jastrow, who discovered the illusion in 1889. There's no mutual agreement as to why it exists, but some scientists believe it has something to do with the difference in radius. The longer curve influences the shorter one and makes it look even shorter, and vice versa.

Notably, some theories suggest that people with autism may not experience visual size illusions due to their excessive focus on details.^[1]