" First up, Blackwell [1972] did a set of experiments on fifty-seven college students to determine the effect of colour—as well as the number of tablets—on the effects elicited. The subjects were sitting through a boring hour-long lecture, and were given either one or two pills, which were either pink or blue. They were told that they could expect to receive either a stimulant or a sedative. Since these were psychologists, and this was back when you could do whatever you wanted to your subjects—even lie to them—the treatment that all the students received consisted simply of sugar pills, but of different colours. Afterwards, when they measured alertness—as well as any subjective effects—the researchers found that two pills were more effective than one, as we might have expected (and two pills were better at eliciting side-effects too). They also found that colour had an effect on outcome: the pink sugar tablets were better at maintaining concentration than the blue ones. Since colours in themselves have no intrinsic pharmacological properties, the difference in effect could only be due to the cultural meanings of pink and blue: pink is alerting, blue is cool. Another study suggested that Oxazepam, a drug similar to Valium (which was once unsuccessfully prescribed by our GP for me as a hyperactive child) was more effective at treating anxiety in a green tablet, and more effective for depression when yellow. Drug "
― Ben Goldacre , Bad Science