I'm trying to find a novel I read over and over as a kid. It was a sci-fi novel. The protagonist lived in a town that he later discovered was false, and was created to keep his true nature hidden from him. All the people, etc. were in on the act. Truman Show-esque, but the motive was to keep him under control. He eventually discovers this and goes through some kind of rapid evolution - his brain grows and he gets psychic powers. I suspect it was written in the 70s - it was a pretty ratty paperback when I was reading it in the 80s, though I suppose it could have been written in the early 80s.
Any ideas?
Any ideas?