Despite its long history, there has been a chronic failure among experts to agree on a definition of hypnosis. In response to this problem, Division 30 (Psychological Hypnosis) of the American Psychological Association generated a definition of hypnosis based on the consensus of a group of eminent hypnosis scholars (Kirsch, 1994). The main points of this definition are as follows:1. Hypnosis is a procedure during which a health professional or researcher suggests that a client, patient, or participant experience changes in sensations, perceptions, thoughts, or behawior. Hypnosis involves an interpersonal interaction between the hypnotist and client. With regard to the topic of this chapter, the hypnotist could be seen as issuing communications designed to induce expectancies for the occurrence of hypnotic responses.2. The hypnotic context is generally established by an induction procedure. Hypnotic inductions may help clients relax and attend to the hypnotic experience] but their primary function is to establish the hypnotic context. In fact, labeling the situation as one in which hypnotic responses are expected and appropriate may be the only common feature across the myriad methods that have been used to induce hypnosis.3. People respond to hypnosis in different ways. Some people are highly responsiwe to hypnotic suggestions and others are less responsiwe. People who are highly responsive to hypnosis tend to describe their experiences as vivid, absorbing, and even profound. At the other extreme are those who merely think about the suggestions and respond only to comply with experimental demands (Radtke & Spanos, 1981; Wagstaff, 1981). Most people fall in between these extremes. Individual differences in hypnotic suggestibility can be reliably and validly measured with standardized hypnotic suggestibility scales. The major scales used in current research include the Stanford Hypnotic Susceptibility Scale, Form C (Weitzenhoffer 6r Hilgard, 1962) and the Harvard Group Scale of Hypnotic Susceptibility (HGSHS; Shor 6r Orne, 1962). Standardized hypnotizability scales typically begin with a scripted eye-fixation/relaxation induction procedure, followed by a set of standard suggestions of varying difficulty. Responses are scored passfail according to objective criteria (e.g., swatting at a hallucinated mosquito). Subjective scoring criteria have also been developed in which respondents rate the vividness or "reality" of their responses (Kirsch, Council] & Wickless, 1990).4. People who have been hypnotized do not lose control ower their behawior. As White (1941) put it, the hypnotized individual strives to "behave like a hypnotized person as this is continuously defined by the operator and understood by the subject" (p. 483). Good hypnotic clients actively process information in the hypnotic situation, thinking and imagining 384