Let's first create 3 examples which, uh, exemplify each of the 3 factors which make deterrence effective. Let's also assume for the sake of the argument, that a person does act rationally (according to his
own framework of morals, of course)
a) Consistency. This is important because if you think that you can get away with something because there's only a 50% chance of being caught and the reward is sufficiently high, you'll at least think about doing it.
b) Appropriate punishment. A slap on the wrist for murdering someone is obviously not a deterrent. However, too harsh a punishment also has its problems - it may produce rebellion or a "I'm not afraid of you!"-type of mindset. In children you may also produce "broken" personalities with too harsh punishments.
c) Temporal adjacency. This is because we're not so good connecting long-term relationships, I mean, we can rationalize about them - but there's also a subconscious part involved - and
that one cannot relate the deed and the punishment if it's too long apart temporally. Just look at a dog who's done something wrong and you slap him with a paper for it - if you wait 2 weeks, the dog won't understand why you just slapped him.
Then there's the group aspect - if you ever worked with a group of people in a supervisory capacity you'll surely have heard those guidelines:
Be consistent. Be fair.
Because if you are not fair, the group (of youths in my case) will NOT like that. They'll think you have favourites. They won't take you seriously. They'll try to work the system by pointing out that you treated a certain situation differently just now than you did before. If you and your co-supervisor don't apply the rules consistently and equally, they'll go to the supervisor first who they think will be less strict. (Replace "supervisor" with "parent" if need be)
As evidence for this group-wide effect for appliance of rewards or punishment, I'll point towards monkeys:
http://news.nationalgeographic.com/n...airness_2.html
I hope this rambling excourse makes it a little bit more clear?