Sequence 1 received 4 weeks of no financial contingency ( i.e. , $ 0 ) drinking followed by 4 weeks each of $ 25 and then $ 50 contingency management ; Sequence 2 received 4 weeks of $ 25 contingency management followed by 4 weeks each of no contingency ( i.e. , $ 0 ) and then $ 50 contingency management .