Optical illusions and teasers
The following image has a number of squares layed out in
concentric circles. Or spirals. I'm confused...
See Richard Wiseman's blog for more information. The Bad Astronomer has some variations to help you understand the illusion better. |
The squares marked A and B are the same shade of gray. 
See the original web page for an explanation of what's happening here. |
In this image, the green and the blue, in their respective spirals, are the same color. Exactly. It doesn't look that way to me, but it can be demonstrated in a couple of different ways. See: |
This math puzzle, obtained from http://www.briandela.com/files/picture.gif (no longer there), is very interesting. Note that this works even if you print this, cut out the pieces, and do it on your desk. Or even if you make your own pieces with the appropriate dimensions. |
Count the black dots in the above image. |
|
|
|
See the Stroop Effect to better understand this picture. |
|
This came from http://blogs.discovermagazine.com/neuroskeptic/2017/12/08/curvature-blindness-illusion/ Curvature Blindness Illusion |
Other places