Richard Wiseman re-posted another great optical illusion this morning which was tweeted to him by @ButMadNNW and @glennbroadway. I think it was originally posted on this interesting looking blog called Things You Wouldn’t Know If We Didn’t Blog Incessantly.
The illusion shows a grid of light and dark squares and at each corner there are 2 black diamonds positioned either vertically or horizontally in an alternate fashion, this is except in the middle, both vertically and horizontally. The ensuing effect is the squares appear bent and like the whole shape is bevelled inwards (or outwards depending on your point of view). It really is quite an impressive effect.
I noticed on the image that the black diamonds didn’t quite line up with lines Wiseman put in to demonstrate that the squares were indeed squares, and thought maybe this was part of the effect, someone else on Wiseman’s blog also noticed this so I recreated it making sure everything was perfectly aligned. The effect still worked.

Original Bent Line Illusion

First Version of the Bent Line Illusion

Bent Lines Illusion With Diamond
What is cool about this illusion (especially now I have my Photoshop patterns set up) is that I think it would be possible to put a simple image into it by changing the orientation of the black diamonds. I will have a play and maybe re-post later.
Thank you Richard and the guys that originally posted this! I love a good optical illusion.