I'm going to have to distance myself from Alicorn on this one. (Surprise, I know.) I think she's confusing the general meaning of "placebo effect" (any positive effect manifesting in a control case) with the specific meaning (curing of a condition attributable at least in part to believing a treatment to work).

The general meaning of it clearly exists and is mentality-independent. For example, after an oil spill, if you dump oil-eating bugs on one part of the affected area, and not the other (the latter being the control), oil will dissipate even in the control, just by natural processes and not because of the bugs. That's a placebo effect baseline against which to compare the bugs.

I endorse the stronger claim that the specific kind exists, and withstands conscious non-belief, so long as you use other modes to trick your body/brain into believing it. This shouldn't be surprising: you behavior is often hard to consciously modify. For example, it's easier to look confident by having a social group you belong to than by trying to control all the micromovements of muscles necessary to give off confident signals.

If that's what Alicorn meant, I apologize, she didn't err, and I agree with her.