hypnosis, reporting bias, and suggested negative hallucinations

8/8/2019 Hypnosis, Reporting Bias, And Suggested Negative Hallucinations

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Journal of Abnor mal Psychology1992, Vol. 101, N o. 1 , 1 9 2 - 1 9 9 Copyr ight 1992 by the Am erican Psychological Association, Inc.0021-843X/92/S3.00

Hypnosis, Reporting Bias, and Suggested Negative HallucinationsNicholas P. Spanos, Cheryl A. Burgess,Patricia A. Cross, and Geoffrey MacLeod

Carleton University, Ottawa,Ontario, CanadaW e examined the role of reporting bias in hypnotic negative hallucinations by using a paradigm inwhich reporting bias was assessed independently of perceptual change. In Experiment 1, highlyhypnotizable subjects reported significant loudness reductions when tested fo r hypnotic deafness.Later, however, these subjects biased th eir reported loudness redu ctions in the absence of perce p-tual change, and their reporting bias scores were almost as large as their h ypn otic deafn ess reports.Subjects also biased their ratings of strategy use. In Exper iment 2, ratings of blindness given inresponse to a hypnotic negative visual hallucination suggestion were significantly correlated withreporting bias scores obtained in this paradigm. Althoug h hypnotic blindness and hypnotic deaf-ness correlated significantly, the partial correlation between these variables wa s nonsignificantwhen reporting bias scores were statistically controlled. The oretical im plications are discussed.

For m ore than a century, hypnosis has been associated withreports of dramatic, suggestion-induced changes in memoryand perception. In m ost cases, however, the only available in-dexes of suggestion-induced experiential change have been ei-ther verbal report or other b ehaviors und er subjects' direct vol-unta ry control. Som e researchers have used indirect indexes ofperceptual an d mem ory change. Fo r example, response to de-layed auditory feedback ha s been used to index hypnotic deaf-ness (e.g., Sutcliffe, 1961). The results of these studies have typi-cally indicated no evidence for perceptual or memory changeon the indirect indexes despite subjects' reportsof experiencingsuggested changes.One interpretation of such findings is that hypnotic sugges-tions rarely if ever produce actual changes in perception ormemory, but instead induce subjects to compliantly bias theirreports in line with suggested demands (Sutcliffe, 1961; Wag-staff, 1981,1986). Com pliant responding is biased responding,and it may be said to occur when subjects report experiencesthat they did not have or exaggerate experiences that the y didhave, in terms of situational demands (Orne & Scheibe, 1964;W agstaff, 1981). Response biases of this kind m ay reflect eitherdem and-induced lying or demand -induced retrospective rein-terpretation of experience. In either case, deman d-induced re-sponse biases reflect misdescriptions motivated by the desire tomeet role expectations (Spanos, 1991; W agstaff, 1981).Although the compliance hypothesis is an old one, it has

failed to gain general acceptance for at least two reasons. First,a nu m ber of investigators have suggested that indirect indexesof perceptual and mem ory functioning do not validly reflectsubjects' experiences. According to this hypothesis, for exam-ple, subjects might show at least partial hearing reduction in

This research wa s supported by a grant from the Na tural Sciencesan d Engineering Research Council of Canada.Correspondence concerning this article should be addressed toNicholas P. Spanos, Department of Psychology, Carleton University,Ottawa, Ontario K1S 5B6, Canad a.

response to deafness suggestions despite behaving in a "non-deaf" manner during delayed auditory feedback (Jones &Flynn, 1989).A second and m ore fundamental difficulty with the compli-ance hypothesis stems from the lack of a methodology withwhich to assess reporting bias indep endently of perceptual expe-rience. Fo r instance, reports of reduced pain or hearing aftersuggestion may to some extent reflect both actual perceptualchange an d demand-induced reporting bias. In the absence ofsome m eans for separating biased responding from perceptualchange, investigators have been free to accept or reject sugges-tion-induced biased responding as a hypothesis on the basisof

personal preference rather than data.Recently, we developed a paradigm that enabled suggestion-induced reporting bias to be assessed directly and indepen-dently of experiential changes during hypnotic deafness(Spanos, Burgess, & P erlini, in press) and hypnotic analgesia(Spanos, Perlini, Patrick, Bell & G wy nn, 1990). For instance,with respect to hypnotic deafness, the paradigm involved ad -ministering an easily audible to ne on three successive trials. A10-s waiting period followed termination of the tone on eachtrial, an d after the waitin g period subjects rated the loudness ofthe preceding tone. The first trial was a baseline, and the sec-ond was preceded by a hypn otic suggestion for deafness. Afterthe second trial, the hyp notic suggestion was canceled an d sub-jects were administered the third tone. After termination ofTone 3, but before subjects made the ir loudness ratings, differ-en t procedures were followed for experimental an d control sub-jects. Control subjects simply waited 10 s and then rated theloudness of Tone 3, as they did on previous trials. In contrast,during the waiting period between the termination of the Tone3 and the loudness rating, experimental subjects were inform edthat they had probably slipped into hypnosis an d heard the lasttone less loudly than they h eard the baseline tone. This in struc-tion was designed to produce reduction in the rated loudness ofTone 3 independ ent of subjects' actual perceptual experienceofTone 3.

192


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HYPNOSIS, COMPLIANCE AND HALLUCINATION 193It is important to keep in mind that up to the termination of

Tone 3, control subjects and experimental subjects were admin-istered identical procedures and, therefore, presumably experi-enced equivalent levels of loudness during presentation of Tone3.Consequently,anyreduction in the rated loudnessof this toneby experimental subjects relative to controls must reflect a re-porting bias rather than a difference in perceptual experience.Control subjects tested in this paradigm reported no significantdifferences in the loudness of Tones 1 and 3. Therefore, forexperimental subjects, reduction inTone 3 loudness ratings rela-tive to Tone 1 loudness ratings served as an index of the degreeto which the demand instruction led subjects to bias their Tone3 loudness reports.

To investigate hypnotic analgesia, we (Spanos, Perlini, et al.,1990) replaced the tone with a pain stimulus and replaced thesuggestion for deafness with a suggestion for pain reduction.

Thus the two studies (Spanos et al., in press; Spanos et al.,1990) in which we have employed this paradigm have yieldedthe following findings. Subjects administered the demand in-struction exhibited significant levelsof reportingbias relative tocontrols. In fact, the degree of Trial 3 reporting bias was usuallyabout half as large as the ratings of deafness and analgesia givenafter the hypnotic suggestion on Trial 2. It is important to notethat the degree of Trial 3 reporting bias correlated strongly withTrial 2 ratings of deafness and analgesia. In other words, peoplewho reported high levels of hypnotic deafness or analgesia onTrial 2 tended to be the same people who exhibited large re-porting biases on Trial 3.

In our paradigm, response to the Trial 3demand instructioncorrelated with hypnotizability to the same extent that hypnoti-zability correlated with Trial 2 ratings of deafness and analge-sia. Furthermore, when level of Trial 3 reporting bias was statis-tically controlled, the correlations between hypnotizabilityanddeafness scores and hypnotizability and analgesia scores weremuch reduced and sometimes no longer statistically signifi-cant. In short, these findings suggest that demand-induced re-porting bias plays an integral role in hypnotic responding andthat much of the reporting change that follows hypnotic sugges-tions appears to be explicable in terms of reporting bias ratherthan in terms of actual changes in subjective experience.

The present study included two experiments aimed at ex-tending the findings thus far obtained with this paradigm.Ex-periment 1 wasconcerned with both the internal validityof theparadigm and the influence of reporting bias on open-endedsubjective reports as well as on perceptual ratings. In Experi-ment 2 we assessed response to suggestions fornegative visualhallucination as well as for deafness, and examined the role ofstrategy use and reporting bias at influencing reports of nega-tive visual hallucination.

Experiment1In our earlier study on hypnoticdeafness and reporting bias

(Spanos et al., in press), both experimental and control subjectswere administered a hypnotic deafness suggestion before Tone2, but received no instructions before Tone 3. As already de-scribed, controls returned to baseline levels of reported loud-ness on Tone 3, whereas those administered the demand in-struction reported less loudness than they had on baseline, but

more loudness than they had on the hypnotic deafness trial(Tone 2). The increase in loudness reported by these subjectsfrom Trial 2 to Trial 3 is open to several interpretations. Onepossibility is that subjects would have reported an increase inloudness across these trials even if they had been administereda hypnotic deafness suggestion before each trial. Alternatively,the higher loudness reported after the demand instruction(Tone 3) than after the suggestion (Tone 2) may indicate thatthe demand manipulation was less potent than hypnotic sug-gestion at lowering loudness ratings.

One purpose of the present study was to assess these alterna-tive hypothesesby testing three groups of highly hypnotizablesubjects on three tone trials. Subjects in Groups 1 and 2 wereadministered, respectively, the control sequence and the de-mand instruction sequence described earlier. Those in Group 3were also administered a Trial 1 baseline tone and a hypnoticdeafness suggestion before Tone 2. However, instead of cance-ling the hypnosis and suggestion after Trial 2, we gave thesesubjects another deafness suggestion before Trial 3.This designenabled us to determinewhether the increase in rated loudnessthat occurs from Trial 2 (deafness suggestion) to Trial 3 (de-mand instruction) reflects differences in the potency of thesuggestion and instruction manipulations or is a result of re-peated exposure to the tone after either suggestion or demandinstruction.

Hypnotic suggestions for perceptual change often explicitlyinstruct subjects to use cognitive strategies to bring about therequisite experiences. Furthermore, subjects who report the per-ceptual experiences called for often report using the strategiescontained in the suggestion or other strategies of their ownmaking (e.g., Spanos, Radtke-Bodorik, Ferguson, & Jones,1979).After Trial 3 all subjects in the present experiment completedfour increasingly explicit questionnaires that asked them to de-scribe their experiences on Trial 3. This procedure allowed usto determine whether subjects given the demand instructionwould bias their postexperimental reports by reporting the useof cognitive strategies and whetheranysuch biasing effects werea function of the amount of information supplied to subjectsbythe questionnaires that purported to assess their experience.

MethodSubjects. Forty-five Carleton University undergraduates volun-teered to participate in a one-session study on suggestion and aud itoryperception. These subjects had previously been scored as highly hyp-notizable (scores of 5-7) on the objective dimension of the CarletonUniversity Responsiveness to Suggestion Scale (CURSSrO; Spanos,

Radtke, Hodgins, Stam, & Bertrand, 1983). All subjects receivedcourse credit fo r their participation.Apparatus and materials. Three identical repetitions of a 30-s, 60-dB, 1000-Hz pure tone were prerecorded on a BASF magnetic tape andpresented to subjects over Sony DR-27 headphones from a PhilipsD8270 tape recorder. Half the subjects received the tone in the left ear,and half received it in the right ear. On each trial, 10 s after terminationof the tone, subjects verbally rated its loudness using a 21-point cate-gory rating scale. This scale contained alternatives ranging from nosound ( Q ) to intensely loud (20).Procedure. All subjects were individually tested by the same femaleexperimenter. Subjects were randomly assigned to o ne of three condi-


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194 SPANOS, BURGESS, CROSS, AND MACLEODtions, with the restriction that there be an equal numberofsubjects ( n =15 ) in each condition. Before their baseline trial, subjects were in-structed to give their loudness ratings after the termination of the tone,when the experimenter tapped the back of their hands (10safter stimu-lus termination). Subjects were requested to close their eyes and werepresented with the baseline auditory test trial.

After the baseline loudness reports, a 10-min hypnotic inductionprocedure (adapted from Barber, 1969) wasadministered to all 45sub-jects. This was followed by a suggestion for deafness that informedsubjects that hypnosis would enable them to use their imaginal andattentional processes to control sensory input and that on the next trialthey wereto usethese abilities to reduce the loudness of the tone. Afte rproviding their Trial 2 loudness ratings, subjects were administeredtheir respective treatments.

Fifteen subjects (the hypnosis group) were given a reinforced hyp-notic deafness suggestion that informed them that they were to con-tinue to relax and drift deeper into hypnosis. This was followed by thesame deafness suggestion administered on Trial 2. After their Trial 3loudness reports, these subjects were awakened and the deafness sug-gestion was canceled.

After making their Trial 2 ratings, the remaining subjects (n = 30)were administered a wake-up procedure and cancellation of the deaf-ness suggestion. For these subjects, Trial 3 was preceded with the in-struction that this last trial would be "just like Trial 1." In the 10 s aftertermination of the Trial 3 tone, but before making their loudness rat-ings, half of these subjects (n = 15) received the following demandinstruction:

People who are exposed to the tone more than once tend to dri f tback into hypnosis, and this greatly reduces the intensity of thesound that they hear. Yo u probably drifted into hypnosis on thislast trial, and for this reason, heard very little of the tone.Theother half (the control group) werenot givenany instruction beforemaking their final loudness ratings.At the end of the third trial (after their loudness ratings), subjectsinall conditions were given three open-ended questionnaires designed toassess their reported subjective experience of the Trial 3 tone. On thefirst questionnaire subjects described everything they had experi-enced on the last trial (Trial 3). On the second questionnaire subjectsprovided more details about what they had experienced on the lasttrial. On the third they reported what, if anything, they had done onthe last trial in order to hear the tone less loudly. Subjects whoreportedusing a strategy on the first questionnaire received a score of 3, thosewho first reported strategy use on the second questionnaire werescored 2, and those who first reported strategy use on the third ques-tionnaire were scored 1. Subjects who failed to report strategy use onany of the questionnaires were scored 0. Two independent judges whowere unaware of subjects' treatment assignment agreed on their strat-egy score 89% of the time.After completing these open-ended questionnaires, subjects wereadministered a 9-point Likert-type scale on which they rated the extentto which they had used imaginal or distraction techniques in order toreduce the loudness of the Trial 3 tone. The scale alternatives rangedfrom not at all (1) to all the time (9).

ResultsReduct ions in reported loudness . A 3 X 3 (Group [hypnosis,

demand, or control] XTrial [1,2, or 3]) mixed analysis ofvari-ance (ANOYA) performed on the loudness ratings yielded asignificant Group XTrial interaction, F(4,84) = 15.84, p


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HYPNOSIS, COMPLIANCE AND HALLUCINATION 195subjects failed to differ significantly from the ratingsof subjectsin the hypnosis condition.

DiscussionOur findings replicate those of earlier studies (Spanos et al,

in press; Spanos et al., 1990) and provide strong support for thehypothesis that reports of suggestion-induced perceptual alter-ation proffered by highly hypnotizable hypnotic subjects re-flect, to a substantial degree, reporting biases rather than ac-tual changes in perceptual processing. In addition, the presentfindings indicate that the increase in loudness reported fromTrial 2 (hypnotic deafness) to Trial 3 (demand instruction) bysubjects given the demand manipulation cannot be explainedin terms of repeated exposure to the tone. Subjects who weregiven the hypnotic suggestion before Trial 2 and again beforeTrial 3 continued to report the same low levels of loudness onboth trials. These findings indicate that hypnotic suggestionswere slightly but significantly more potent at inducing reportsof deafness than was the demand instruction employed in thisresearch. These findings might mean that Trial 2 loudness re-duction scores reflect a small perceptual alteration componentthat was added to a reporting bias component. Alternatively,these findings might simply mean that hypnotic suggestionscontained stronger demands to bias perceptual reports thandid our demand instruction. Regardless of which hypothesiseventually proves true, the present findings clearly supportWagstaff's (1981,1986) contention that suggestion-induced re-porting bias is a central component in hypnotic responding.

Subjects given the deafness suggestion before Trial 3 re-ported more use of cognitive strategies in their open-ended re-ports than did either control subjects or subjects given the de-mand instruction. As already mentioned, only subjects giventhe Trial 3 suggestion maintained equivalent levels of reportedloudness reduction across Trials 2 and 3. One interpretation ofthese findings is that strategy use led to the greater-than-de-mand loudness reductions in subjects given the Trial 3 sugges-tion. On the other hand, these findings could indicate thatsubjects who received the Trial 3 suggestion were particularlylikely to indicate strategy use because only these subjects hadbeen given a suggestion that explicitly instructed them to usestrategieson Trial 3. The open-ended questionnaires, by them-selves, contained fewcues that strategy reporting was required.Consequently, most subjects given the demand instruction mayhave been unaware that such reporting was called for. However,when these subjects weregiven the final Likert-type scale thatexplicitly asked them to rate the extent of their strategy use,their ratings on this dimension were as high as those of thesubjects given the Trial 3 deafness suggestion. In other words,subjects were quite willing to bias their reportsofstrategy use aswell as their loudness reports. However, such biasing was un-likely to occur in the demand instruction condition until thesesubjects were provided (viaan explicit questionnaire) with therequisite information about the responses called for. Such infor-mation was provided by the suggestion for those subjects whoreceived a suggestion before Trial 3. Consequently,for subjectsin this condition, open-ended reports of strategy use and therelationship between such reports and reported loudness re-ductions remain ambiguous. It would be of interest in a future

study to administer deafness suggestions that did not providecognitive strategies. If subjects who received these suggestionscontinued to report greater strategy use on open-ended ques-tionnaires and greater loudness reductions on Trial 3 than sub-jects given a demand instruction, support would be providedfor the hypothesis that strategy use produces effects on percep-tual reports above and beyond the effects of reporting bias.

Experiment 2Negative visual hallucinations are suggestion-induced re-

ports of an inability to see a target stimulus. Negative visualhallucination suggestions are among the most difficult itemson standardized hypnotizability scales (Hilgard, 1965) and areusually "passed" by only highly hypnotizable subjects. Al-though relatively little empirical work has focused on negativevisual hallucinations, some evidence indicates that reportingbias may play a prominent role in this phenomenon.

Spanos, Flynn, and Gabora (1989) gave highlyhypnotizablesubjects the suggestion that, on opening their eyes, they wouldseeonly a blank piece of paper. In fact, the number 8 was dis-played prominentlyon the paper. Subjects who reported seeingnothing on the paper were interviewed by a second experi-menter, who implied to them that seeing nothing was the re-sponse typically given only by fakers, whereas seeing a figurethat gradually faded over1min was typical of trulyhypnotizedpeople. Subjects were then giventhe opportunity to draw whatthey had seen on the paper at successive points after they hadopened their eyes. Under these circumstances, 14 out of 15 sub-jects who had initially insisted that they saw nothing on thepaper now drew a number 8 as the figure seen when they firstopened their eyes. In other words, when demands to reporthaving "seen nothing" were l if ted, almost all of these highlyhypnotizable subjects acknowledged through their drawingsthat they had seen the target figure they had earlier deniedseeing.

These findings do not mean that subjects in the Spanos et al.(1989) experiment failed to experience any perceptual distor-tion after the suggestion. Byemploying simple ocular strategiessuch as unfocusing the eyes, or averting gaze from the targetstimulus, subjects can easily produce blurring and other distor-tions of visual perception. Subjects in the Spanos et al. experi-ment and in other experimentson negative hallucination maywell have employed such strategies to induce perceptual distor-tions. Nevertheless, Spanos et al.'s findings suggest that, regard-less of any such distortions in perception, subjects clearly exag-gerated their experiences in line with suggested demands bystating that they could see nothing on the paper.

Although hypnotic subjects are exposed to explicit demandsto gear their reports in line with the requests of suggestions,they are also exposed to implicit demands to report honestlyand accurately about their experiences (deGroot & Gwynn,1989; Spanos, 1986). Furthermore, hypnotic subjectsare likelyto differ substantially in the extent to which theyaresensitivetonorms for honest reporting. Consequently, such subjects arelikely to exaggerate and distort their experiences to differentdegrees in response to experimental demands.

Although the Spanos et al. (1989) study indicated that nega-tive hallucinators exaggerate their experiences in terms of sug-


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196 SPANOS, BURG ESS, CROSS, AND MACLEODgested demands, it provided no means of assessing individualdifferences in the degree of such reporting bias. Moreover, nei-ther Spanos et al. nor other researchers have assessed the cogni-tive strategies that subjects employ in order to distort their per-ceptual experiences and define themselves as "not seeing."

In Experiment 2, we assessed the strategies for "not seeing"that subjects reported in response to a negative visual hallucina-tion suggestion and examined the relationship between the useof such strategies and the degree to which subjects reportedblindness. In addition, the role of reporting bias in negativevisual hallucination responding was assessed by testing sub-jects in the deafness paradigm described in Experiment1 andexamining the relationship between bias scores obtained in thatparadigm and blindness scores obtained in response to a nega-tive visual hallucination suggestion. We anticipated that report-ing bias in the deafness paradigm would correlate significantlywith reports ofblindness after the suggestion fornegative visualhallucination.Method

Subjects. Forty-nine Carleton University undergraduates volun-teered to participate in a study of perception and hypnosis. Thesesubjects had p reviously tested as either m edium (scores of 3 or 4) orhigh (scores of 5-7)on the CURS&O (Spanos et al., 1983). All subjectsreceived course credit for their participation.Procedure. All subjects were tested individu ally by the same maleexperimenter in twosessions. In the first sessionsubjects were asked toclose the ir eyes and w ere administered the 10-min hypnotic inductionprocedure used in Experiment 1. This was followed by a suggestion forblindness that info rmed subjects that they were to become activelyinvolved in the suggestion and were to use whatever strategies the ycould to m ake a word disappear from a piece of pap er. Subjects werethen instructed to look at an 8.5 in. X 11 in. sheet of white paper thatwas held approximately 50 cm in front of their eyes. On the paper wa sprinted the word DINOSAUR in letters20 m m in height. The sugges-tion instructed subjects to notice that the word was fading more andmore, un til it completely disappeared and the p aper w as blank . Theywere then asked to describe what they saw on the paper. FollowingBryant and McConkey (1989), subjects who reported seeing all or par tof the word DINOSAUR were given a prompt that encouraged them totry harder and to use w hatever strategies they could to m ake the wordfade an d disappear. After the prom pt, these subjects were again askedwhat they saw on the paper.After theirverbal reports,a wake-up pro-cedure was administered and the blindness suggestion was canceled.Blindness scores were computed as follows. Subjects who in their ini-tial descriptions reported seeing nothing on the paper were given ablindness score of 2 . Subjects who initially reported seeing all or part ofthe word but reported comp lete blindness after the promp t received ascore of 1. Finally, subjects wh o failed to report b lindness despite theprompt received a score of 0.

Subjects were next administered a 5-point scale asking them to ratethe extent of their blindness. Scale alternatives ranged from not at all(0) to completely (4). After completion of this hypn otic blindness self-rating, subjects wrote responses to a one-page, open-ended question-naire that asked them what, if anything, they had done in order to "notsee" the w ord. This questionnaire was scored for cognitive strategy useby two independent judges wh o were unaware of subjects' exper imen -tal condition and level of hypnotizability. Judges scored each subject asreporting strategy use (1) or not reporting strategy use (0). Judgesagreed 92% of the time, and discrepancies were resolved through dis-cussion.Finally, the subjects were given a list of seven possible strategies and

were asked to circle as many as they had used in their attempt to makethe word disappear. These strategies were listed as follows:1. I unfocused my eyes.2. I crossed my eyes.3. I looked above, below, or away from the word, rather thanlooking right at it.4. I created a visual image to cover or block the word.5. I tried to imagine a different word.6. I tried to th ink of other things, so as not to notice the word.7. Other (specify).

Subjects were tested in a second individual session within 2 weeks ofthe first. Du rin g the second session, 34 subjects were administered thedeafness paradigm with the demand instruction after Tone 3 in thesame manner as in Experiment 1. The remaining15 subjects were ad-ministered the control sequence of the paradigm. After their loudnessratings all subjects were administered two open-ended questionnairestaken from Experiment 1 (Questionnaires 1 and 3) that assessed re-ported strategy use during the Trial 3 tone. Subjects were scored 2 i fthey reported strategy use on the first questionnaire, 1 if they reportedstrategy use on the second questionn aire, and 0 if they failed to reportstrategy u se on either qu estionnaire. Two independent judges agreedon these ratings 92% of the time.Results

Compl iance and control. A Hotelling's T2 analysis that com-pared the scores of Session 2 experimental and control subjectson the CURSS dimensions, open-ended blindness reports,blindness scale self-ratings, and judges' blindness strategy useratings failed to approach significance. Thus subjects in thedemand instruction and control conditions were equivalent onthese measures.Sess ion 2 exper imenta l e f f e c t s . A 2 X 3 (Condition [demandinstruction or control] X Trial [1, 2, or 3]) mixed ANOV\ onloudness ratings yielded a significant interaction, F(2, 94) =3.88, p < .025, that was analyzed further in terms of simplemain effects. As shown in Table 2, the simple main effects forcondition at Trials 1 and 2 failed to approach significance, indi-cating that subjects in the demand instruction and control con-ditions of Session 2 reported equivalent levelsof loudness onthese two trials. However, a significant simple main effect wasfound for condition at Trial 3,F(l, 70) = 6.28, p < .025. Subjectswho received the demand instruction reported significantlylower Trial 3 loudness ratings than did the nondemand (con-trol) subjects.

Analyses within conditions revealed that significant changesin the loudness of the tone across trials were reported by sub-jects given the demand instruction, F(2,94) = 30.14,p


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HYPNOSIS, COMPLIANCE AND HALLUCINATION 197trols), F(2,94) = 20.42, p < .001. Post hoc comparisons (leastsignificant difference) indicated that subjects given the demandinstruction reported significant loudness reductions on Trial 2(suggested deafness) and on Trial 3 (demand instruction). How-ever, Trial 3 reported loudness reductions were significantlysmaller than those of Trial 2. The nondemand subjects re-ported significantly lower loudness on Trial 2 than on Trial 1 or3. Loudness ratings on Trials 1 and 3 failed to differ signifi-cantly.Report ing bias in "blind" and"not bl ind"subjec t s . Analysesofrelationships between Session 2 reporting bias and response tothe Session 1negative visual hallucination suggestion includedonly those subjects who were administered the demand in-struction in Session 2. For each of these subjects, a Session 2reporting bias score was obtained by subtracting their Trial 3(demand instruction) loudness score from their Trial 1 score.W e anticipated that subjects who reported complete blind-ness in Session 1would report greater Session 2 reporting biasthen subjects who reported little or no blindness in Session 1.This hypothesis was tested in an analysis that included onlythose subjects who rated themselves as exhibiting completeblindness (self-rating of 4, n = 11 ) or little or no blindness (self-rating of 1 or 0, = 9) in Session 1. As predicted, subjects whoreported complete blindness (M = 3.73, SD = 2.65) exhibitedsubstantially and significantly greater Session 2 reporting biasthan those who did not report blindness (M= .33, SD =3.24),/(18) = 2.58 p < .05.

Strategies for blindness and deafness . On the basis of theirSession 1 open-ended reports, 40 subjects (82%) were rated asusing one or more strategies in an attempt to "not see" thetarget word. However,in response to the seven-item list ofstrat-egies, all subjects reported using at least one strategy. The per-centages of subjects who chose each listed strategy are given inTable 3. Twelve subjects (24%) chose Strategy 7 on the strategychecklist, indicating that they had used strategies other thanthe available choices. Closer examination revealed that 8 ofthese subjects (67%) reported ocular fixation on only a limitedaspect of the stimulus (i.e., staring fixedly at a letter or portionof the word D IN O S AU R ) ; 2 subjects (17%) described sensationsexperienced during the suggestion, such as a blurriness of vi-sion, rather than reporting a specific strategy; 1subject reiter-ated that he had visualized a piece of white paper covering the

Table 3Number and Percentage of Subjec t sWho Repor ted Using Each Strategy

1 .2.3.4.5.6.7.

StrategyI unfocused my eyes.I crossed my eyes.I looked above, below, or away from the word,rather than looking right at it.I created a visual image to cover or block theword.I tried to imagine a different word.I tried to think of other things, so as not tonotice the word.Other (specify).

No. ofsubjects33729134612

%6714592781224

word (Strategy 4); and the remaining subject simply reported "Iblanked mymind."

A t test comparing Session 2 demand instruction and controlsubjects on auditory strategy scores obtained from the open-ended questionnaires failed to approach significance. As in Ex-periment 1, subjectswho receivedthe demand instruction (M =.74, SD = .57) reported no greater use of cognitive strategies toreduce the loudness of the Trial 3 tone than did control subjects

Correlat ions. Table 4 shows the correlations among the de-pendent variables assessed in Sessions1 and 2 forsubjectsgiventhe demand instruction in Session 2. Difference scores wereused to compute Session 2 deafness scores (baseline-Trial 2)and reporting bias scores (baseline-Trial 3).

In Session 2, the correlation between Trial 2 deafness scoresand Trial 3 reporting bias scores was substantial and indicatedthat to a large extent subjects who reported high levels of hyp-notic deafness were the same persons who, on the next trial,biased their reports in terms of experimentaldemands. Interest-ingly, the extent to which subjects biased their reports on Trial 3also correlated significantly with the extent to which they re-ported use of cognitive strategies on that trial. In other words,subjects who biased their reports of hearing reduction to a rela-tively large degree also tended to be attuned enough toexperi-mental demands to generate reports of strategy use on the basisof the minimal cues provided by the open-ended question-naires.

In Session 1, the correlation between open-ended reports ofblindness and self-ratings of blindnesswas very high and sup-ports the notion that these two indexes assessed the same re-sponse dimension. Neither of these Session 1 blindness indexescorrelated significantly with the extent of strategy use reportedby subjects in response to the negative visual hallucination sug-gestion. On the other hand, both Session 1 blindness indexescorrelated significantly with Session 2 deafness ratings and re-porting bias scores. More important, the partial correlationsbetweendeafness ratings and open-ended reports of blindness,r(31) = .03, and between deafness ratings and self-ratings ofblindness, r(31) = .22, were not significant when the effects ofreporting bias scores were statistically controlled. Reportingbias scores, like blindness scores, did not correlate significantlywith the extent of subjects' strategy use in response to the Ses-sion 1suggestion. Taken together, these findings indicate thatreporting bias influenced response to suggestions fornegativevisual hallucinationaswellas response to deafness suggestions.Moreover, the correlation between reports of suggested blind-ness and deafness was mediated by subjects' tendency to biastheir perceptual reports in terms of suggested demands.

General DiscussionThe findings of Experiment 2 concerning suggested deafness

replicate those of Experiment 1 as well as those of Spanos et al.(in press) and indicate that demand-induced reporting biasplays an important role in the phenomenon of hypnotic deaf-ness. The results of Experiments 1 and 2 further indicate thatcompliance pressures lead subjects to bias their reports of audi-tory strategy use as well as their reports of reduced hearing.When assessment proceduresexplicitly implied that the report-


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198 SPANOS, BURGESS, CROSS, A N D MACLEODTable 4Correlations Among Session1 and Sess ion 2 Dependent Variables in Experiment 2

Variable 11. Suggested deafness2. Reporting bias3. Deafness strategies4. Judges' blindness ratings5. Self-ratingsof blindness6. Blindness strategies

.79** .39*.35* .31*.37*.03.42**.38*.03.82**

.04.02.1 1

.04.04*p


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HYPNOSIS, COM PLIANCE AN D HALLUCINATION 199Bryant, R. A., & McConkey, K . M. (1989). Hypnotic blindness, aware-ness and attribution. Journal of Ab no r m a l Psychology, 98 ,443-447.deGroot, H. P,&Gwynn , M. I. (1989). Trance logic, duality and hid-den observer responding. In N. P. Spanos & J. F. Cha ves (Eds.), Hyp-nosis: Th e cognitive-behavioral perspective (pp. 187-205). Buffalo,NY : Prometheus.Hilgard, E. R. (1965). Hypnotic susceptibility. New York: Harcourt,Brace & W orld.Jones, W . D., & Flynn, D. M. (1989). M ethodological and theoreticalconsiderations in the study of "hypnotic" effects in perception. InN. P.Spanos & J. F.Chaves (Eds.), Hypnosis: Th e cognitive-behavioralperspective (pp. 149-174). Buffalo, NY: Prometheus.Orne, M. T. (1959). The nature of hypnosis: Artifact and essence. Jour-na l of Ab no r m a l and Social Psychology, 58 , 277-299.Orne, M. T., & Scheibe, K . E. (1964). The contribution of nondepriva-tion factors in the production of sensory deprivation effect: Thepsychology of the "panic button." Journal of Abnormal and SocialPsychology, 68, 3-12.Sarbin, T. R., & Coe, W C. (1979). Hyp nosis and p sychopathology:Replacing old myths with fresh metaphors. Journal of Ab no r m a l Psy-chology, 88, 506-526.Spanos, N. P. (1986). Hypnotic behavior: A social psychological inter-pretation of amnesia, analgesia and trance logic. Behavioral and

Brain Sciences, 9, 449-467.Spanos, N. P. (1991). A sociocognitive approach to hypnosis. In S. J.Lynn & J. R. Rhu e (Eds.), Hypnosis theories: Current models andperspectives (pp. 324-361). N ew \brk: G uilford Press.Spanos, N. P., Burgess, C. A., & Periini, A. H. (in press). Complianceand suggested deafness in hypnotic and nonhy pnotic subjects. Imagi-nation, Cognition an d Personality.

Spanos, N. P., Flyn n, D. M., & Gabora, N. (1989). Suggested negativevisual hallucinations in hypnotic subjects: W hen no mean s yes. Brit-ish Journal of Experimental and Clinical Hypnosis, 6, 63-67.Spanos, N. P., Periini, A. H.,Patrick , L., Bell,S,& Gwynn, M. I. (1990).The role of compliance in hypnotic and nonhypnotic analgesia.Journal of Research in Personality, 24, 433-453.Spanos, N. P., Radtke-Bodorik, H. L., Ferguson, J., & Jones, B. (1979).The effects of hypno tic susceptibility, suggestions for analgesia andthe utilization of cognitive strategies on the reduction of pain. Jour-na l of Ab no r m a l Psychology, 88, 282-292.Spanos, N. P., Radtke, H. L., Hodgins, D. C, Stam, H. J., & Bertrand,L. D. (1983). The Carleton U niversity Responsiveness to SuggestionScale: Normative data and psychometric properties. PsychologicalReports, 53 , 523-535.Sutcliffe, J. P. (1961). "Credulous" and "skeptical" views of hypnoticphenomena: Experiments on esthesia, hallucination and delusion.Journal o f Ab no r m a l and Social Psychology, 62 ,189-200.W agstaff, G. F. (1981). Hypnosis, compliance an d belief New York: St.Martin's Press.W agstaff, G. F. (1986). Hypnosis as compliance and belief: A sociocog-nitive view. In P.Naish (Ed.), What is hypnosis?(pp. 59-84). Philadel-phia: Open University Press.Zamansky, H. S. (1989). Discussion com men tary on "Suggested nega-tive visual hallucinations in hypnotic subjects." Bri t ish Journal ofExperimental and Clinical Hypnosis, 6, 67-70.

Received December 6,1990Revision received May 14,1991

Accepted May 18,1991

hypnosis, reporting bias, and suggested negative hallucinations

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