The placebo effect doesn't just make people think they're experiencing something when they're not, it's not merely a mental phenomenon, it can have actual physical effects and remarkable ones, ones you wouldn't imagine could be the result of placebo. There ARE thing it can't do, IDK whether hair regrowth is on the list, but I highly doubt it, because there's just so many amazing effects it can have, regrowing balding hair seems like a minor feat in comparison.I'm not sure how you could placebo yourself into hair growth. I think this is impossible. Positive thinking won't grow hair. Of course it's amatuerish to allow trial subjects to talk to each other, but in the case of a hair loss trial I don't think it's such a big deal aside from side effects.