This is apparently a well documented phenomenon, but when you see a series of faces in rapid succession in your peripheral vision, they look grotesque and distorted.
To see this effect, click through these images (or use your keyboard’s left/right keys) and keep your eyes on the gray cross in the center. Crazy.
It’s amazing how much they look like cartoon caricatures. My guess is that caricature artists have learned how to amplify this natural effect in their drawings. Pretty cool stuff.
Source: This GIF