Inverse placebo effect
The inverse placebo effect, also known as the "knowcebo" effect (or "know-cebo" effect) or suppressed placebo effect, is a phenomenon in psychology and medicine in which a person in a blinded clinical trial knows that they have received placebo due to functional unblinding problems and this results in the person experiencing diminished placebo effects. The effect is especially relevant in trials of strongly psychoactive drugs such as psychedelics.