I agree that this is a bad flaw but the reasoning about the “nocebo” effect does make sense: administering a placebo actually confounds the results if the parti

I agree that this is a bad flaw but the reasoning about the “nocebo” effect does make sense: administering a placebo actually confounds the results if the participants know it’s a placebo, and it will be pretty obvious it the pill you took doesn’t have any psychedelics. Studies like these are inherently difficult, this isn’t an issue of poor design.