The Ponzo illusion is a type of optical illusion that demonstrates how our brain interprets depth and size based on perspective. It relies on the concept of linear perspective, where converging lines give the impression of depth, similar to how railway tracks appear to converge in the distance. In this illusion, two horizontal lines of identical length are placed between converging lines, and our brain perceives the upper line as being longer than the lower one, even though they are actually the same length.
This illusion occurs because our brain uses context to interpret the size and scale of objects. The converging lines create a sense of depth, making the upper line appear farther away. Since our brain is accustomed to objects that are farther away appearing smaller, it compensates by interpreting the upper line as being larger. This effect highlights how visual perception is influenced by the context in which an object is seen, and demonstrates the way our brain processes depth and size relationships.
The sliders in this interactive tool allow you to adjust the length of the vertical lines and the position of the right line, giving you a chance to explore how these changes affect your perception of the illusion. By interacting with the illusion, you can better understand how easily our visual system can be tricked by perspective cues.