The placebo effect works if your brain thinks that you think that it will work, if I understood things correctly.
And yes, that I can't reliably self delude, and even if I could it would be prone to backfire, is exactly what causes this to be a problem.
I'm decently sure that my brain does not store beliefs separately from confidence, affect, etc.
I thoguh that was exactly the point of the dementor sequence; that it was an impossible paradox.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
If continuing the discussion becomes impractical, that means you win at open threads; a celebratory top-level post on the topic is traditional.