I've been reading this book about this very topic, the book is called " PORNIFIED: How Pornography is transforming our lives, familes and relationships "

this book has opened my eyes to so many things, and how excessive amounts of porn really change the way people think towards certain things. and how it's affecting people at a younger age because it's so accessible.

larry clark did a little documentary on this similar topic also, called Impaled, pretty cool shit.