x7eggert wrote:Nope, it does work in any case.
Well, let's be precise. There were a couple of small-scale studies which suggested that placebos were more effective against irritable bowel syndrome and migraines than no treatment, even when people knew they were just taking sugar pills with no medicinal effect. This has been overblown by the press into "placebos work even if you know they're placebos". Which is a claim that goes way beyond what's actually been established. We're not yet clear on how known-placebos compare to unknown-placebos. Yes, known-placebos can apparently have an effect, but so far, they've only been compared to no treatment!
At the moment, the best we can say is that knowing you're taking a placebo doesn't seem to entirely ruin the placebo effect. Which is indeed a surprising result, but you shouldn't read more into it than is there.
Also, the effects of placebos (known or unknown) are fairly limited. A study of placebo on asthma showed that its effect can be to make the sufferer feel better without actually improving their breathing. Which is a dangerous thing to do, since the sufferer may then neglect to seek more effective treatment.