Studies designed to elicit the full strength of the placebo effect differ from those in which the placebo effect represents a nuisance factor to be accounted for in order to establish the efficacy of a treatment. In the latter, informed consent is the rule; in the first, while consent may be informed in some narrow sense of the word, deception is common. However, the trickery of placebo experimentation goes beyond straightforward lies to include the use of crafty ambiguities, half-truths, and deliberate omissions in scripts read to the subjects of these studies. As words come to resemble therapeutic agents in their own right, it is only to be expected that researchers would methodically exploit verbal effects to evoke the responses they are looking for. Even experiments in which placebo is disclosed as placebo have used language in leading and misleading ways. Such studies are conducted in the hope of yielding results that might translate into clinical practice, but it should be noted that good clinical practice has a placebo value of its own--that is, confers a benefit over and beyond the specific effects of treatments--even if nothing like a sugar pill is administered.
Keywords: consent; deception; placebo; suggestion.