[Alex3917]

>If it was merely an issue of "someone who cares about [the patients]" then we'd expect that the actual drugs would benefit from the same effect too.

Great point, this could completely sink my theory. Two arguments though:

1) If the placebo was less effective than the drug and they both gained the same amount of efficacy, then mathematically the placebo is now more effective relative to the medication.

2) It doesn't seem possible to really debunk my theory without taking a look at how patients are recruited for experimental drug studies, as I can imagine the standard procedure being such that my theory would still hold. but I don't know enough about this to say much offhand.

Anyway I'm not going for a Nobel prize in science, but if I were then this is still what I'd bet on.

edit: I wonder if watching funny movies has become more effective over time. This would be an interesting preliminary test.