an optical illusion wherein the upper of two parallel horizontal lines of equal length looks like it is longer than the bottom of the two lines whenever oblique lines are placed perpendicular to the two other lines on each of their ends which are closer together at the top than at the bottom. Commonly referred to as railway lines illusion.

PONZO ILLUSION: "The concept of the Ponzo illusion was aptly named for its founder, Mario Ponzo, an Italian psychologist."
Cite this page: N., Pam M.S., "PONZO ILLUSION," in PsychologyDictionary.org, April 7, 2013, https://psychologydictionary.org/ponzo-illusion/ (accessed October 15, 2021).