Wrong author - try David Brin (Score 2, Informative)

I've read (nearly) all of PKD's books, and I don't recall seeing any mention of anything like brain screening. I love PKD, but really, he gets too much credit. The best literary reference I can think of is David Brin's excellent "Sundiver," in which one of the characters lives the life of a second-class citizen after having failed a battery of tests designed to screen for violent or perverted impulses. David Brin's latest book, "Kiln People," is also quite good, and utterly unlike anything I've read. Check it out.