There are numerous examples of the relationship between treatment expectations and placebo responses [2]. If a person thinks they will experience relief from their pain by using a certain product or treatment, this can change the way they end up perceiving [3] incoming pain signals – making them think their pain is less severe. Recent evidence suggests that the placebo effect may work even if we're presented with evidence that contradicts our initial expectations [4].
We cannot say with 100 percent certainty that media coverage is responsible for the high placebo response observed in our review. But given placebos were shown to be just as good as cannabis for managing pain, our results show just how important it is to think about the placebo effect and how it can be influenced by external factors – such as media coverage.