7. The method of claim 6 , the training set comprising: a first content item associated with a first reward, and a second content item associated with a second reward that is different from the first reward.
7. The method of claim 6 , the training set comprising: a first content item associated with a first reward, and a second content item associated with a second reward that is different from the first reward. 8. The method of claim 7 : respective human classifiers having a human classifier rating; and the reward delivered to a human classifier calculated proportionally to the human classifier rating of the human classifier.