Parallelogram illusion


The only browser that currently runs Java applets is Firefox where, too, you have to make the site cut-the-knot.org trusted in the Java setup

Parallelogram illusion


What if applet does not run?

Which red line is longer?

A few words

|Contact| |Front page| |Contents| |Geometry|

Copyright © 1996-2018 Alexander Bogomolny

Parallelogram Illusion

The red lines do not appear to be of equal lengths, but they are. Checking the "Show hint" box helps with overcoming doubts.

The brain dissects the picture and attempts to interpret it into distinct separate objects, as is the case with, say, Kanizsa triangle. It recognizes two parallelograms -- one smaller, the other bigger -- even when the midline is not present. All parts of the bigger parallelogram appear begger by association.

|Contact| |Front page| |Contents| |Geometry|

Copyright © 1996-2018 Alexander Bogomolny

71471070