I think I get and actually agree with that part of Arth's view: there are many different effects being controlled for with placebo, and this study only shows one such effect. In many cases where placebo controls are necessary, this effect probably isn't involved at all. For instance, early in the thread there was discussion of a surgery that was studied with placebo control (they basically did the exploratory part without the intervention part of the surgery, so the patient was still put under anesthesia and still had to be cut open). The result of that study was that the placebo group and the intervention group had similar results, suggesting that the actual intervention was ineffective.
I think there's a third control group with no intervention, including placebo, (though I may remember wrong), who did worse than both. But I doubt that the reason the placebo group does better than that control is because of an actual physiological mechanism. In that case, it's probably just all the issues of subjective reporting that have been discussed in this thread.
So, to sum up, there may actually be cases where there's a real physiological mechanism involved in placebo effects. The mouse study is evidence in that direction. But there are also other effects involved, and its very likely that in many (most?) cases there is no physiological mechanism involved. Saying "this study explains the placebo effect" suggests that this is the whole of what the placebo effect is, whereas it is at most a contributing factor in some cases.
If that’s what arthwollipot meant, then certainly I agree with him, and with you. But that's a somewhat odd way of putting it, then. …I mean, take the paranormal, that I referred to earlier:
Let’s say, hypothetically, that, crazy as it sounds, one of those nutjobs that used to come up on the earlier JREF threads, claiming they could read your mind, and divine the numbers you’ve thought of continents away from them, is indeed able to convincingly support this claim of theirs of the paranormal. Or maybe they do that in a full-on lab study, not just here, online. Point is, let's assume they do it. ...Well now, first of all, that only demonstrates that some kinds of telepathy sometimes work, not that every kind of telepathy therefore works; and it most certainly does not indicate that every claim of telepathy is therefore true. Second of all, it is a demonstration only of telepathy, and not of other kinds of paranormal claims like, I don’t know, dowsing, and prophesying future events, and speaking with the dead, and recollection of “past life” memories from long ago. But despite that, it wouldn’t really make sense to therefore assert that reports that this experiment demonstrates the paranormal are wrong. It does indeed prove the paranormal, and it would certainly merit the million dollars, had that still been on offer. Right?
…In any case, let’s not get hung up over whether that precise wording works or not, or whether some podcaster meant something correctly, or whether some news report’s been sensationalized. Like I said, to me the really important thing, that I wanted to be clear about, is that this experiment does seem, so very unexpectedly, to indicate that expectations can drive physiological relief for causes that are not themselves psychosomatic in nature. …What Pixel42 said earlier, that this just one study, and therefore not definitive, makes sense, absolutely; and we should wait before more studies prove this more conclusively, and not rush to believing just yet that this very extravagant principle is a thing. …That said, if indeed this is true, then surely that’s a …huge, really huge thing? Because that might end up opening up
valid application of this principle across categories that we’d thought have been completely debunked and rejected, like healing by touch, and healing by pilgrimage, reiki, chakric healing, acupuncture, homeopathy, the works --- in very limited cases, for instance when bona fide treatment is not available or is medically inappropriate, and that too for very specific kinds of ailments not everything under the sun, but still.