The present research climate shows a distinct preference for a retrocausal mechanism for PSI phenomena. This is in no small part due to interest in "The Question of Time" by the physics community at large. For example, at the 2011 AAAS Meeting in San Diego, a symposium Quantum Retrocausation: Theory and Experiment drew papers from such phyics luminaries as Fred Alan Wolf, Avshalom Elitzur and Henry Stapp in addition to researchers focussed on PSI research itself, such as Dean Radin, physicists Richard Shoup and York Dobyns, and the new poster child for PSI research, psychologist Daryl Bem. The physical mechanisms examined can be roughly divided into two catagories: "quantum effects" and "reversed time flow".
My own bet is with the first of these--which, for want of a better term we can call Quantum Weirdness. For example consider the Magic Square game (click on figures at the left to get more information) that can always be won by 2 profoundly separated quantum players, but who in a classical world must fail 1/9 th of the time, no matter what strategy they adopt. Suppose one saw two such players, winning again and again: Approached with a classical mind-set, the only conclusion seems to be "the players have some kind of telepathy between them, even though it may be unconscious". Approached with the tools of quantum mechnics (or QM), one would say, no, that's not telepathy, they are "able to cooperate perfectly because (maybe) they each hold a package of particles, each particle of which is entangled (by some previous action) with a corresponding member of the package held by the other player"! And one would go on to define experiments to test that. Maybe it's because researchers haven't asked the right questions that PSI research is still stuck with telepathy (clairvoyance) and retrocausation as likely explanations.
What's more, QM allows us to cooperate non-classically not only in pairs, as above, but also in 3's 4's. In each of these cases, quantum cooperation achieves a level of success that is just not possible in a classical world. This provides a possible or even likely explanation for one of the most puzzling characteristics of PSI research--that the experimenter him- or herself seems to be an important factor in determining the experimental results. Thus the "decline effect" and "experimenter effect", widely problematic in experimental PSI studies and discussed at some length in papers at the recent SSE conference, seem to indicate that one of the "participants" is surely the experimenter, non-classically cooperating with his subjects; and seemingly most effective when highly motivated while the experiments are new and fresh.