Originally Posted by FrannieP
the placebo effect, by definition requires one to have psychological expectations and beliefs that are not seen in the early stages of infancy, or in animals - for whom homeopathic remedies are also often very effective.
that's not actually the definition
of a placebo, per se. that's more like an interpretation
of a placebo effect.
a placebo is just an attempt to make the control environment as similar as possible to the test environment. that's really all. so if the test subjects are taking some drug in pill form, what are you going to compare that to? rather than comparing that to control subjects who are doing nothing, you compare it to control subjects who are also taking pills (ie "placebos"). there may be any number of confounding factors that are avoided by having control subjects take the placebo -- for example, the swallowing of a pill, or the stimulation of the digestive tract, or the driving to the test center, or the process of being selected for a clinical trial, or (as you suggest) the psychological beliefs associated with taking pills. (the placebo itself may also, of course, confound the test: the placebo substance may, for example, have some unanticipated physiological activity.)
but the point is that placebo use implies no assumptions about the provenance of the possible effectiveness of placebo as a treatment. it's just an attempt to control as many variables as possible in recognition that biological systems are very
complex. i think there's a widespread assumption that placebos have some clinical activity for certain conditions because of the subjects' personal beliefs or psychological suggestion or similar reasons. that may or may not be true, but it's difficult to prove, and it's wholly irrelevant to placebo-controlled studies: they're not studying why (or even whether) placebos
work, but whether the test substance
this may reflect poor methodology, but ultimately the term "placebo effect" refers to the observation (real or imagined) that
placebos have some effect, but not necessarily why