Monthly Illusions and Brain Teasers Part 1


To keep things both fun and interesting we are starting a series of illusions and brain teasers that we'll feature on a monthly basis here on the Eyes On Broadway blog. Below is installment #1, with a focus on visual illusions this time around. Enjoy! 

Adelson's Checker Shadow Illusion

This illusion is pretty interesting from the standpoint of visual context. Known as "Adelson's Checker Shadow Illusion," and published by Edward H. Adelson, view the image below and specifically the two squares marked "A" and "B." Do these two squares appear to be the same color? Well, thanks to the shadow falling on square "B," it appears much lighter in color vs. square "A." The fact is...they are exactly the same shade of grey. Use an eyedropper in a graphics program to truly test this...but indeed it's true!   portland-eye-doctor  

The Same Grey

This illusion is pretty amazing. Believe it or not, the surfaces of both the "A" top and the "B" bottom are exactly the same shade of grey in the image below. Once again, you can use an eyedropper to validate this...but more simply, just cover the portion where the top and bottom's meet...and you'll see it's true!   portland-eye-doctor  

Three Perfect Squares

Of course it doesn't look right, but the three squares in the middle of the image below are perfect squares. Their juxtaposition to the angular pattern make them appear "non-square." Measure to be sure!   portland-eye-doctor  

The Corner House Illusion

I like this illusion a lot as it looks different, depending on which part of the image you cover with your hand. So the basic question is: is the vertical corner in the image concave or convex? Well, this just depends. See what you think by covering up the upper half with your palm. Now try covering the lower half. Any thoughts?   portland-optometrist   Look for more illusions and brain teasers next month! Header Image Courtesy: