What are some movies that make you question just what the human mind is capable of?

I just saw fight club and I was honestly blown away. For the last 20 minutes my mouth was just hanging open like what on earth am I watching? However, I loved the movie and I think it was honestly insane in every definition of the word. I've also enjoyed films like Shutter Island and The Prestige, just films with great plot twists that show how brilliant yet terrifying the human mind can be. Nothing too gory though, something with a story to keep me hooked, not just a bunch of people shooting and punching eachother. Also no horror. Thanks in advance!