Social psychological factors in the genesis of posthypnotic source amnesia.

Abstract

Three experiments assessed the role of social psychological variables in source amnesia. Experiment1 found that low-hypnotizable subjects instructed to simulate partial amnesia were more likely toexhibit source amnesia than high-hypnotizable hypnotic or task-motivated subjects. Experiment 2found equivalent rates of source amnesia in low-hypnotizable simulators and high-hypnotizablehypnotic subjects. In addition, the findings of Experiment 2 failed to support the idea that the in-structions for partial amnesia given to simulators cued for the occurrence of source amnesia as wellas for the occurrence of partial amnesia. In Experiment 3, preliminary instructions that legitimatedsource amnesia as role-appropriate response produced significantly more posthypnotic sourceamnesia than did neutral or no instructions. Together, the findings of the three experiments supportthe relation of source amnesia to experimental demands and subjects' expectations.Hypnotic phenomena are viewed by some investigators as in-volving special psychological processes that differ in fundamen-tal respects from the processes involved in everyday wakingsocial behavior. Those who adopt this theoretical perspectivehave attempted to delineate psychologica l processes that arespecific to and tha t cannot be accounted for ade-quately in terms of social-psychological antecedents (Evans,1979; Orne, 1979). One phenomenon frequently touted as be-ing a counter expectational effect of hypnosis is source amne-sia (Evans, 1979, p. 557).Source amnesia occurs when subjects recall previouslylearned information but indicate that they do not know wherethe information was learned (Evans, 1979). In typical study,subjects are administered hypnotic induction procedure fol-lowed by series of questions concerning little known facts (e.g.,In what year was born?). Subjects who do not knowthe correct answers are given them (e.g., Freud was born in1856). Following these procedures, subjects are administereda suggestion to be amnesic for everything that occurred duringthe hypnotic session. Those who exhibit amnesia for the eventsof the session are asked the same question again. In this situa-tion some of the subjects who initially did not know the answersnow give correct answers. Following each correct answer, sub-jects are asked, How did you know that? Some subjects failto indicate that they learned the correct answer during the hyp-notic session. These subjects state that they do not know wherethey learned the answer, or they supply the incorrect source fortheir answer (e.g., I must have read it somewhere). Subjectswho respond in this manner are classified as exhibiting sourceThis research was supported by Grant from the National Sciencesand Engineering Research Council of Canada awarded to Nicholas P.Spanos.We thank W. Cross and J. Smith for aid in testing subjects.Correspondence concerning this article should be addressed to Nich-olas P. Spanos, Department of Psychology, Carleton University, Ottawa,Ontario, Canada K1S 5B6.According to special process theorists, subjects who exhibitsourc e amnesia remember th facts that they learned duringhypnotic session but ar e unabl (as opposed to unwilling)specify where they learned these facts (Evans, 1979; Kihlstrom,1978 , Orne 1966 1979). An alternative socia psychologicaaccoun suggest s tha sourc e amnesia reflect on of several pos-sible strategies for dealing with an ambiguous test situation(Coe, 1978; Spanos, 1986b; Wagstaff, 198 la). According to thisperspective, high-hypnotizabl e hypnotic subjects ar investedin presenting themselves as deeply hypnotized (Spanos,1982; Wagstaff, 1981a). This self-presentation requires morethan the performance of role appropriate overt behavior. In or-der to meet implicit demands for honest or genuine hypnoticresponding, subjects must do what they can to align their sub-jective experiences with the contents of the instructions andsuggestions that they are given (Sarbin & Coe, 1979; Spanos,1986a).As prelude to exhibiting source amnesia subjects must cor-rectly answer question with information they acquired onlya few moments earlier during the hypnotic procedure. Whenunexpectedly asked the critical question How do you knowthat? such subjects are placed in an ambiguous situation. Therole appropriate hypnotic response to this question is not clearand, for this reason, subjects probably adopt different interpre-tations of what is called for. For instance, some subjects maychoose to acknowledge the source of their answers because theyhave already given part of what was asked for. Others may viewthis situation as another opportunity to present themselves asamnesic by denying that they know the source of their answer.Still others may pick up on any interest shown by the experi-menter in their hesitation about supplying the correct sourceand thereby come to define source amnesia as an appropriateresponse to be repeated if future opportunities arise (Coe, 1978;Spanos, 1986b; Wagstaff, 198 la).According to special process theorists, source amnesia is acounterexpectational response. Supposedly, it reflects cognitivealterations that are greatly facilitated by hypnotic procedures,but that are unrelated to the situational demands of the source322