If you ever create a slideshow of portraits, you might want to avoid showing them aligned side-by-side with a gap in between. The video above shows a crazy optical illusion that researchers have dubbed the “Flashed Face Distortion Effect”. By flashing ordinary portraits aligned at the eyes, the human brain begins to compare and exaggerate the differences, causing the faces to seem hideous and ogre-like.
via petapixel.com
Make sure you stare at the cross so that the faces are in your peripheral vision. I noticed them becoming two-dimensional, almost cartoonish, as well as being distorted.