Got this vintage poster from somewhere, and took me ages to see the illusion. The problem was I had trouble understanding the instructions written on top of the poster, so I simply ignored them and did this my way. My advice would be to look at the picture as if you were staring at some stereogram. Now switch from normal to cross-eyed view (cross your eyes as if you had strabismus), and repeat this procedure back and forth. Do you see the hand with the “ball” going towards horse’s mouth? It shouldn’t be much of a problem. What bugs me, is that I don’t see the “ball” being ball at all! What I see is someone trying to drug the horse with steroids, in order to win a horse-race! Am I the only one who finds this unethical and simply wrong? Perhaps it’s just my twisted-gambling character speaking here!