A friend, and colleague, gave an amazing speech on how to control a class using behavior modification techniques. He has studied this topic intensively and well qualified to lecture on it. Alas, I am not so here are some links to places where you can get better information on the subject.
This is a good site that explains it well but not necessarily directly useful in our lessons.
Good explanation, but best to avoid some things like; hugs, and touching in general.
More types of reinforcers and their effects
More in depth reading
Full publication on the subject.