The perception of butyric acid and isovaleric acid can be manipulated by associating them with parmesan cheese or vomit.

“if they say this is parmesan cheese they go oh yeah that's parmesan cheese and if they give it to other people and say this is vomit they'll go oh yeah that's vomit and if they tell people they give them one vial and say this is peran shees and they go yeah and they give them another one they say it's vom they go yeah and then they say well actually we fooled you it was the same vial they say no you didn't you must have made a mistake they're convinced that they couldn't have been the same thing”