NPR has a short piece on a fascinating study where the researchers informed hotel maids that their normal work counted as exercise, which had the effect of making them more physically fit, despite them not seeming to change their activity levels.
Unfortunately, the NPR segment seems to suggest that the study ‘challenges the placebo effect’, based on the faulty assumption that the placebo effect only alters ‘subjective perception’.
In fact, placebos are known to affect outcome in a range of physical illnesses (and even produce placebo ‘side-effects – known as the nocebo effect), and they have been shown to directly stimulate the same brain circuit when they are used to replace a drug to treat Parkinson’s disease.
Furthermore, the study itself [pdf] claims to demonstrate the placebo effect in a new domain.
Despite this, it’s a fascinating study and raises a number of intriguing questions, such as whether the placebo effect is directly affecting body metabolism, or whether the information given to the maids just made them behave differently, and actually do their work in a way to give more health benefits.