This has been all over the internet so here's one explanation.
Hosted by: Hank GreenRelated:
Like SciShow? Want to help support us, and also get things to put on your walls, cover your torso and hold your liquids? Check out our awesome products over at DFTBA Records: http://dftba.com/scishow
Or help support us by subscribing to our page on Subbable: https://subbable.com/scishow
Looking for SciShow elsewhere on the internet?
Facebook: http://www.facebook.com/scishow
Twitter: http://www.twitter.com/scishow
Tumblr: http://scishow.tumblr.com
Instagram: http://instagram.com/thescishow
Sources:
http://www.wired.com/2015/02/science-...
Do You See Albert Einstein Or Marilyn Monroe In This Photo?
Can You See A Duck Or A Rabbit? This Optical Illusion Says A Lot About Your Creativity
Optical Illusions In Art
