These faces have not been altered in any way.
It’s a new scientific finding called the “Flashed Face Distortion Effect”. You can read more about it here
Tangen, J. M., Murphy, S., & Thompson, M. B. (in press). Flashed face distortion effect: Grotesque faces from relative spaces. Perception advance online publication, doi:10.1068/p6968.
Thanks to http://3d.sk for the faces.