The critical evaluation of new drugs or remedies against inert substances or nonspecific procedures has led to the recognition that responses to a placebo are important in their own right. Such responses may be dramatic and persistent and they can be associated with quite definite physiological changes (Wolf and Pinsky, 1954). The placebo response may well be an important component of many established treatments both physical and psychological, and does in itself constitute a means of therapy (Roberts and Hamilton, 1958; Gliedman et al., 1958).