Online Community Reward Systems – Detailed Mechanics

I'm looking for any published research on reward systems in online communities ( such as those rep stats up top right on here ).

What I'm looking for is any research on the detailed mechanics.

Say whether in the system it works by the user having a pot of reputation 'money' which they can spend - voting other users up or down and when the money has gone it’s gone. Until some activity gives them some more rep money to spend. And does down-voting have the same 'cost' as up-voting ??

And then does a high rep give them 'superpowers' on the board - and are they really motivated by the number of Bronze, Silver, Gold badges they have acquired ?

All this kind of stuff really (if anyone has ever researched it)