Anales de Psicología ISSN: 0212-9728 [email protected] Universidad de Murcia España Kirsch, Irving Hypnosis and Placebos: Response Expectancy as a Mediator of Suggestion Effects. Anales de Psicología, vol. 15, núm. 1, 1999, pp. 99-110 Universidad de Murcia Murcia, España Disponible en: http://www.redalyc.org/articulo.oa?id=16715108 Cómo citar el artículo Número completo Sistema de Información Científica Más información del artículo Red de Revistas Científicas de América Latina, el Caribe, España y Portugal Página de la revista en redalyc.org Proyecto académico sin fines de lucro, desarrollado bajo la iniciativa de acceso abierto anales de psicología © Copyright 1999: Servicio de Publicaciones de la Universidad de Murcia 1999, vol . 15, nº 1, 99-110 Murcia (España). ISSN: 0212-9728 Hypnosis and Placebos: Response Expectancy as a Mediator of Suggestion Effects Irving Kirsch University of Connecticut Titulo: Hipnosis y placebos: la expectativa de respuesta Abstract: In this paper, data are reviewed indicating that como mediador de los efectos de la sugestión hypnotic and placebo effects share a common mechanism: Resumen: En este artículo se revisan datos que sugieren response expectancy. Placebos and hypnotic procedures que los efectos de la hipnosis y de los placebos comparten may have therapeutic effects because they change the un mismo mecanismo: la expectativa de respuesta. Los client's expectations. Both placebo and hypnosis are placebos y los procedimientos hipnóticos tienen efectos viewed as instances of the broader phenomenon of terapéuticos porque modifican las expectativas de los suggestion. While other variables may play important roles clientes. Se conciben ambos como ejemplos del fenómeno in the response to suggestions, it remains to be known más amplio de la sugestión. Otras variables pueden jugar un whether they affect responses by changing expectations or papel importante en la respuesta a las sugestiones, pero aún have a direct impact on them. The potential disdvantages of falta por saber si afectan a dichas respuestas a través de una using the idea of trance in therapy are also discussed. modificación de las expectativas o tienen un impacto Key words: Hypnosis, placebo, suggestion, response expec- directo sobre las respuestas. Se discuten también los efectos tancy negativos de la utilización de la idea del trance en la terapia. Palabras clave: Hipnosis, placebo, sugestión, expectativa de respuesta Hypnosis is a procedure in which a person gestions contain challenges. Amnesia sugges- designated as hypnotist suggests changes in ex- tions, for example, require that the person not perience to a person designated subject (Kirsch, recall particular information. These hypnotic 1994; Kirsch & Lynn, 1995). A representative phenomena have been characterized as the range of hypnotic suggestions are sampled in "domain of hypnosis" (Hilgard, 1973). An standardized scales of suggestibility, most of adequate theory of hypnosis should be able to which are highly reliable and substantially cor- account for the full range of behavior con- related with each other (Council, in press). tained in this domain. Suggestions on these scales are generally There are many books and journal articles thought to be of three basic types. Ideomotor focusing on the topic of hypnosis and hypno- suggestions are suggestions that a particular ac- tizability. In contrast, despite notable excep- tion, such as an arm rising in the air (arm levi- tions, such as the work by Amigó (in press) tation), will occur automatically, without and Capafons (in press) at the University of awareness of volitional effort. Challenge sugges- Valencia, the broader subject of suggestion has tions are suggestions that the person cannot been relatively neglected. There are historical perform an act that is normally under volun- reasons for this state of affairs. The effects of tary control, such as bending an arm (arm ri- mesmerism and hypnosis have seemed so un- gidity). Cognitive suggestions are suggestions for usual that many observers dismissed them as various cognitive or perceptual distortions, fraudulent, and others attributed them to some such as selective amnesia, pain reduction, and special condition or state. It seemed impossi- hallucinations. Note that some cognitive sug- ble for suggestion to have such extraordinary effects, without there being some kind of spe- cial state creating them. * Dirección para correspondencia / Address for corres- pondence: Irving Kirsch. University of Connecticut. Storrs, The results of research on hypnosis in the CT 06269-1020. United States of America. twentieth century have clearly invalidated that E-Mail: [email protected] conclusion. One of the first things that was - 99 - 100 I. Kirsch learned through experimental research on most clearly indicates the need for a change in hypnosis was that all behaviors seen in hypno- focus from the topic of hypnosis to the topic sis can also be obtained without hypnosis. of suggestion. Hilgard's data indicated that the Clark Hull (1933, p. 391) wrote: effect of hypnotic inductions on suggestibility The only thing which characterizes hypnosis as such were generally quite small. A person who re- and which gives any justification for calling it a "state" sponds to six of the twelve suggestions con- is its generalized hypersuggestibility. That is, an in- crease in suggestibility takes place upon entering the tained in a typical hypnotic suggestibility scale hypnotic trance. The difference between the hypnotic is likely to respond to five of them even with- and normal state is therefore quantitative rather than out the induction of hypnosis (Kirsch, 1997). qualitative. No phenomenon whatever can be pro- duced in hypnosis that cannot be produced to lesser Some of the effects of hypnosis may not degrees by suggestions given in the normal waking be suggested by the hypnotist. The best known condition. the essence of hypnosis lies in the fact of of these is so called spontaneous amnesia, change in suggestibility [emphasis in the original]. which in past centuries was a hallmark of hyp- These data suggest that suggestion, rather than nosis, but currently is virtually nonexistent. Al- hypnosis, is the fundamental phenomenon on though not directly suggested by the hypnotist, which we should focus. these phenomena are far from spontaneous. This conclusion is reinforced by two more Instead, they too are products of suggestion-- recent sources of data. One is the work of in this case, suggestions that are transmitted by nonstate theorists, and in particular, the ex- the culture. Young and Cooper (1972) demon- perimental work of T. X. Barber and his fol- strated this quite nicely. They told one group lowers. It was Barber (1969) who most clearly of subjects that hypnotized people experience demonstrated that all of the observed effects spontaneous amnesia, and they told a second of hypnosis, including the increase in suggesti- group that hypnotized subjects do not experi- bility that was observed following a hypnotic ence spontaneous amnesia. The subjects were induction, could be duplicated by nonhypnotic later tested for their beliefs about hypnosis. procedures. Thus, hypersuggestibility, the sin- Forty-eight percent of those in the first group gle remaining justification that Clark Hull agreed, with the statement "If I were to be could find for retaining the trance concept, hypnotized I would not remember what had can be produced by nonhypnotic methods. happened after I woke up (Young & Cooper, Importantly, the Barber Suggestibility Scale 1972). In contrast, only 15% of the second differed from previous scales in that it in- group expected to experience spontaneous cluded a measure of subjective or experiential amnesia. When later hypnotized and tested for response to suggestion, as well as a measure of so called "spontaneous" amnesia, 37% of the behavioral response. Thus, Barber was able to subjects in the first group displayed it, com- demonstrate that thesubjective responses to pared to only 10% of the in the second group. suggestion did not depend on the induction of Thus, the occurrence of amnesia was hardly a hypnotic trance. This, of course, cast doubt "spontaneous." This is further confirmed by on the concept of hypnotic trance, doubt another interesting finding in these data. which has been reinforced by the failure to Across both groups, 75% of the subjects who find any physiological or even self-report expected amnesia experienced it, whereas markers of the hypothesized state. It turns out none of those who did not expect amnesia ex- that the most prominent experts cannot distin- perienced it. This illustrates a central theme of guish the self-reports of hypnotized subjects this paper: the mediating role of expectancy in from those of subjects who have not been the ability of suggestion to elicit a response. hypnotized (Kirsch, Mobayed, Council, & What makes hypnosis interesting is peo- Kenny, 1992). ple's responses to such suggestions as analge- Paradoxically, it is the work of E. R. Hil- sia, amnesia, age regression, nonvolitional gard (1965) on suggestibility as a trait that movements, and positive and negative halluci- anales de psicología, 1999, 15(1) Hypnosis and Placebos: Response Expectancy as a Mediator of Suggestion Effects 101 nations. Without phenomena such as these, nonvolitionally, rather than emitted intention- there would be little to interest scholars or lay ally. Often this distinction is clear in the phras- persons in hypnosis. So if these responses do ing of