Brick Wall 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

Brick wall illusion


What if applet does not run?

A few words.

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Copyright © 1996-2018 Alexander Bogomolny

The parallel lines do not often look parallel.

The applet helps observe the well known Brick Wall Illusion: when the consecutive brick layers of intermittent colors are shifted against so that the vertical boundaries between the bricks are made to cross the layer boundaries, the layers do not seem to be parallel. The effect disappears as the amount of mortar between the layers increases.

Below is a picture (courtsey flickr) of a building in Melbourn, Australia.

In fact it takes very little to observe the illusion, not even a couple of lines expected to be parallel:

The illusion is clearly related to the Twisted Cord one.

Related material
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  • Height/Width Interplay
  • Assimilation Illusion
  • Balls and Shadows Illusion
  • Bulging Lines illusion
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    Copyright © 1996-2018 Alexander Bogomolny

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