[vog]

This is an incorrect summary of the placebo effect. The placebo effect does require the patient to either believe it is effective, or at least not knowing clearly it is ineffective.

This is why clinical studies don't tell neither group (neither the treated group nor the control group) who is in which group, to not spoil the results.

And also, this is why homeopathy puts so much effort into spreading the belief they are effective despite all odds, up to the point of trying to convince people to abandon basic scientific principles.

[BalinKing]

GP is actually correct according to Wikipedia[0] (for what that's worth): There seems to be evidence that "open-label placebos"—i.e. "where the patient is fully aware that the treatment is inert"—still have positive effects.

[0] https://en.wikipedia.org/wiki/Placebo#Effects

[vog]

Contrast this with advertisement, which actually does work even when people know that it is ads, and which still does work on people how know how ads work.

Also, contrast this with psychotherapy, which usually does work even better if the patient understands how it works, because it enables them to become an active and more effective part of the therapy.

[tpoacher]

studies don't tell you about being on a placebo because of blinding, not because it would stop the placebo from working.