# Ponzo illusion

> English word · Noun

## Definitions
1. An optical illusion whereby a horizontal bar looks wider when farther up a picture of railroad tracks than when lower.

## Etymology
First demonstrated by the Italian psychologist Mario Ponzo (1882–1960) in 1911.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/ponzo-illusion