Figure 8.33: Depth-processing explanation of the Ponzo illusion If this were a real, three-dimensional scene, not a photograph, and the red bars really existed as shown, the one in the background would not only look larger but would be larger than the one in the foreground.
(Adapted from Gregory, 1968.)
Sorapop Udomsri/Shutterstock
Sorapop Udomsri/Shutterstock