In general, studies dealing with preparatory sets can be classified as transfer of training models. However, important differences exist between these and the more typical transfer paradigms. In the latter, the original learning OL and transfer test TT phases are typically quite similar often the tasks are essentially the same degree of difficulty and differ only in the specific stimuli and responses to be learned. In this sense, the two phases of the experiment consist of autonomous units, each, in the absence of the other, of parallel form and difficulty. In the type of study considered in this paper, the OL task may be quite simple in comparison to the transfer task, as in the typical warm-up WUstudy, or, preparation may consist of a vast number of problems, administered over a significant portion of the life of the individual, as occurs in some forms of the learning how to learn paradigm. Also, as pointed out by Arnoult 1957, the research on the effects of preparatory tasks tends to question the notion that the S-1--R-1 S-1--R-2 paradigm in transfer leads unequivocally to negative transfer. Because of the formidible mass of relevant studies, the authors chose to make some rather arbitrary and restricting boundaries. As the title indicates, they are concerned with those paradigms having implications for human learning, and because of their strong transfer of training bias, their attention is directed primarily to studies interpretable within this framework.