Note that that study doesn’t itself have anything directly to do with the placebo effect. They made fake pictures of boxes of pills, with different colours, and asked people questions like “What do you think this drug would be used to treat?” and “How effective would you expect it to be?”. They didn’t give any drugs (real or fake) to anyone.
(That isn’t intended as a criticism of the study: it’s fine that it wasn’t studying the placebo effect—nor of acephalus’s citation of it: it does indeed have some relevant references. Just a cautionary note.)
Relevant excerpts on colour and vomit.
And here’s a relevant study on Pharmaceutical Packaging Color and Drug Expectancy which has some references.
Note that that study doesn’t itself have anything directly to do with the placebo effect. They made fake pictures of boxes of pills, with different colours, and asked people questions like “What do you think this drug would be used to treat?” and “How effective would you expect it to be?”. They didn’t give any drugs (real or fake) to anyone.
(That isn’t intended as a criticism of the study: it’s fine that it wasn’t studying the placebo effect—nor of acephalus’s citation of it: it does indeed have some relevant references. Just a cautionary note.)