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International Journal of Clinical and Experimental Hypnosis Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/nhyp20
Physiological Responsiveness During Hypnosis a
Laura M. Sturgis & William C. Coe a
b
Honolulu, Hawaii
b
California State University , Fresno Published online: 31 Jan 2008.
To cite this article: Laura M. Sturgis & William C. Coe (1990) Physiological Responsiveness During Hypnosis, International Journal of Clinical and Experimental Hypnosis, 38:3, 196-207, DOI: 10.1080/00207149008414518 To link to this article: http://dx.doi.org/10.1080/00207149008414518
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Tln I n u r n u i o d ] o u r d of Clinicd and E x p m m c d H y p l w r r v 1880. Vd.LWIII. No. 3. 196-m
PHYSIOLOGICAL RESPONSIVENESS DURING HYPNOSIS’ LAURA M. STURGIS Honolulu. Harwii AVD
WILLIAM C.COE2
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California State University, F r e m
Abstract: 4 physiological measures -electromyogram, respiration rate, heart rate, and skin conductance - were recorded for 11 high and 11 low hypnotizable Ss. It was hypothesized (a) that physiological responsiveness during hypnosis would vary depending on the nature of the task instructions, and (b)that high hypnotizable Ss would show more physiological responsiveness tban low hypnotizable Ss. The first hypothesis was substantiated across all 4 measures. Only heart rate levels supported the second hypothesis. The results are discussed as they relate to the 2 hypotheses and to future research.
Research attempting to uncover various physiological indicants of hypnosis (e.g., basal metabolic rate, blood volume, respiration rate, electroencephalograph [EEG], peripheral blood flow, heart rate, skin conductance, muscle tension - electromyograph [EMG], etc.) has been reviewed earlier by a number of investigators (Barber, 1961, 1970: Crasilneck & Hall, 1959; Edmonston, 1979; Levitt & Brady, 1963;Sarbin, 1956, 1973; Sarbin & Slagle, 1972; Spanos, 1982). The general conclusion has been that the intensity and duration of physiological responses in hypnosis vary in much the same way as they do outside of hypnosis. In fact, Damaser, Shor, and M. T. Orne (1963)found that simulating Ss showed similar physiological changes as did real Ss. demonstrating that “suggested” versus “requested emotions had no unique physiological pattern. It therefore appears that reliable physiological correlates of hypnotizability have not been demonstrated, nor can hypnosis be viewed as accompanied by unique, physiological properties (Barber. 1961; Spanos, 1982). The nature of the hypnotic induction, prior hypnotic experience, and specific task instructions, however, are some of the variables that have helped to account for the otherwise confusing discrepancies in the literature. For example, when Ss took literally the typical suggestions of relaxation and drowsiness in hypnotic inductions, their skin conductance declined (Barber & Hahn, 1963; Bauer & McCanne, 1930; Estabrooks, Manuscript submitted March 28.1988; find revision received December 26, 1989. ‘The study met in part the senior author‘s requirements for the Masters of Arts degree at California State University, Fresno. ‘Reprint requests should be addressed to William C. Coe. Ph. D.. Department of Psychology, California State University. Fresno. CA 93740-0011.
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1930; Levine, 1930). Conversely, skin conductance levels did not change for Ss who had had prior hypnotic experience, presumably because they had learned to remain alert and prepared for upcoming task instructions (Barber & Coules, 1959). Davis and Kantor (1935) also demonstrated the differential effects of instructions on skin conductance by comparing active and quiescent hypnotic states. With relaxation and sleep instructions, conductance decreased, resembling conductance levels achieved during typical sleep. During the active condition, conductance levels resembled those seen when awake. The degree of organismic involvement in the role of hypnotic S is the focus of the present study. The present authors would predict that highly responsive hypnotic Ss become more organismically involved in hypnosis than do less responsive S s and are thereby more convincing S s to themselves as well as to others (e.g., Coe & Sarbin, 1977; Sarbin & Coe, 1972, 1979). Also, in keeping with our emphasis on the interaction of environmental events and S variables, it is predicted that Ss’ physiological activity would covary with the nature of the hypnotist’s instructions (suggestions). For example, the suggestions for relaxation, etc. during the induction period should result in less physiological arousal than other suggestions which ask for specific responses.
METHOD Subjects
Two hundred sixty introductory psychology students were screened using a taped administration of the Harvard Group Scale of Hypnotic Susceptibility, Form A (HGSHS:A) of Shor and E. C. Orne (1962).Thirty Ss were selected initially as highs (score of 9 or more) or lows (score of 3 or less). The find samples after screening for reliability on the Stanford Hypnotic Susceptibility Scale, Form C (SHSSC) Weitzenhoffer and Hilgard (1962) consisted of 11 high hypnotizables (9 female, 2 male) and 11 low hypnotizables (8 female, 3 male). Their mean age was 19.5 years. All participated for credit in an introductory psychology course. Apparatus3
The Narco Bio-Systems Physiograph P M P 4 was used to monitor Ss’ physiological responses during the hypnotic session. The speed of the ’Schematic diagrams of the N m B i o Systems Physiograph and the electmmyograph
(EMC)equipment may be obtained from the National AuxiliPry Publications Service (NAPS). A table of the means and standard deviations for each physiologicpi measure on the 11 items may also be obtained from NAPS. For 5 pages order document No. 04776 from ASIS-NAPS, do Microfiche Publications, P. 0. Box 3513, Grand Central Station. New York, NY 101633513. Remit in advance in U.S. funds only $7.73, for photocopies or $4.00 for microfiche and make checks payable to Microfiche Publications NAPS. Outside the United States and Canada, add postage of $4.50 for a photocopy and S1.50 for a fiche. There is a $15.00 invoicing fee for orders not prepaid.
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physiograph paper was set at 2 cm/second, and each physiological measure was recorded simultaneously by a separate pen on the same sheet of Paper. Three EMG surface electrodes filled with conductive cream were placed over S’s frontalis muscle, approximately 3.8 cm above the eyebrows, with the ground electrode located in the center. All three electrodes were held in place by an adjustable rubber headband. The electrodes were plugged into one of two EEGlEMG NB-132 Preamplifiers which fed into Channel 2 of an EEG/EMG Filter Module NB-122 of the Narco EEG/EMG Biofeedback System. The filter module was set for a range of 100 Hz to 500 Hz. An EEG/EMG Calibrator NB-192, which injected a 200-Hz, 12-microvolt signal, was attached to the other preamplifier which fed into Channel 1 of the filter module. A switch on the filter module made it possible to shift &om Channel 1 to Channel 2, so that the calibration of the equipment could be checked or changed during the session. The feedback signal output of the filter module was connected to the auxiliary input of a Type 7070 Channel Amplifier in the Physiograph and recorded by Pen 1. The EMG amplitude was indicated on the graph by the position of the recording pen. Center position represented a 1 2 - k ~EMG signal, and each centimeter square represented a change of 2kv. Respiration rate was measured using a Bellows Pneumograph attached to an ESG Coupler Type 7211, which measures changes in air pressure, producing a pen movement on the graph. The monitor output of the ESC coupler was connected to the auxiliary input of the channel amplifier and the signal was recorded. The paper speed of 2 cmlsecond allowed for clear discrimination of the respiration wave form. Heart rate was monitored using a Photoelectric Pulse Transducer Type 323 fastened to the thumb of S’s nonpreferred hand and attached to a Transducer Coupler Type 7173. The transducer fed directly into Channel Amplifier 2 and was also coupled with a Biotachometer Type 7302 which fed into Channel Amplifier 3. Heart rate was measured in beats per minute. The actual pulse as viewed on the paper served as the dependent measure. Skin resistance was measured using two Narco soft lead skin resistance finger electrodes. After normal cleaning and without any electrolyte, the electrodes were fastened to S’s index and middle fingers over the proximal phalanx of the nonpreferred hand. The electrodes were attached to a GSR Coupler Type 7175, which fed into the Channel 4 amplifier with the signal being recorded. The GSR was set for direct coupling so that the actual skin resistance in kilohms was recorded. The coupler was calibrated for 10 Kilohmskm. on the vertical axis and 2 cmlsecond on the horizontal axis.
Procedure The Ss were randomly assigned to experimental sessions. The S was escorted into the experimental room, introduced to the two Es, and
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instructed to sit in a large, reclining armchair. The nature of the study was explained as an investigation of physiological responsiveness during hypnosis. After the instruments were attached, S was requested to sit quietly while base rate measures were taken and channel adjustments for response range were made. After base rates, E 1‘ began administration of SHSS:C. The E 2 (L.M.S.) attended to the physiograph in an adjacent room and received visual and auditory feedback of the session via a three-camera, remote control, video-audio system. Any irregularities that might S e c t the physiological measures could be recorded (e.g.. movement of S’s nondominant hand, rocking, moving the head, etc.). Fortunately, no irregularities of any magnitude were observed. The hypnotist wore a miniature radio receiver so that E 2 could communicate without disturbing S. The E 2 monitoring the physiograph delineated each of the 12 periods precisely by placing a mark on the recording paper at the beginning and end of each 10-second interval. Items 2 and 3 (moving hand apart and mosquito hallucination, respectively) were deleted from SHSS:C because of the possibility of S dislodging the skin resistance electrodes and heart rate monitor attached to the nonpreferred hand. Directions for Items 1, 5, and 8 were modified to the use of S’s dominant hand in order to avoid moving the electrodes on the nonpreferred hand. Only the data from Ss who demonstrated high consistency between the two hypnosis scales (HGSHS:A and SHSS:C) were analyzed. High scorers on HGSHS:A had to pass 8 of 10 remaining SHSS:C items; lows could pass no more than 4 SHSS:C items. Twenty-two out of 30 Ss tested met these criteria.
RESULTS Physiological Scores Each physiological measure was computed from 10-second intervals. The intervals were selected with the intent of capturing SP responses at points of maximum involvement, either to relax or to become alert for tasks. The 12 intervds were: (1) base rate - the 10 seconds before immediately following the the start of the induction; (2) induction deepening count fiom 1 to 20; (3) Item 1 (hand lowering) during the prescribed l0-second scoring period; (4) Item 4 (taste hallucination) directly after the first query for sour taste; (5) Item 5 (arm rigidity) during the l0-second scoring period; (6) Item 6 (dream) following the initial 60 seconds of the dream period; (7) Item 7 (age regression) immediately following the count to “2” for regression to the second grade, but before S was questioned, since any verbal activity would confound EMC scores; (8) Item 8 (arm immobilization - left arm) during the 10-second scoring period; (9) Item 9 (anosmia to ammonia) immediately after the initial
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‘We wish to thank Laura Kuhn for assisting as hypnotist.
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sniff of amnonia; (10) Item 10 (hallucinated voice) after the hypnotist’s statement, “There’s the first question”; (11)Item 11(negative visiial hallucination)just after S was told to open eyes and look at the two boxes, but before the questioning about what was seen; (12) Item 12 (posthypnotic amnesia) during the first recall period. The pen tracings for each measure were transformed to the data. Heart rate and respiration rate were computed by counting the number of obvious humps (each heart beat or respiratory cycle) traced during the l0-second period. The result was multiplied by 6 to convert to beats per minute. The EMC readings were converted by adding the p v levels at each 1-second interval during the 10-second time period, then dividing by 10 to obtain the mean for each period. Skin conductance level was based on the mean calculated from 10 one-second samples.’ The base rate measures were used to compare any changes during the induction-relaxation period and each of the selected scoring periods. None of the base rate measures differed significantly between high and low hypnotizable Ss (all t’s < 1.0). Accordingly, Ss’ means of their 11 raw physiological scores for EMG, respiration rate, and heart rate, were subtracted from their mean base rate scores. Constants were then added to difference scores in order to prevent negative scores.’ Specific difference scores for each measure were computed as follows: (a) heart rate = mean beats/minute/period (item), minus basal rate, plus 15. (Thus, 15 equals no change from basal rate.) (b) EMG = mean mv/crn2/period (item), minus basal rate, plus 16. (c) respiration rate = mean cycles/minute/period (item), minus basal rate, plus 10. (d) skin resistance (kilohms/cm*)was transformed into skin conductance (micromhodcm’), its reciprocal, the preferred measure according to Greenfield and Sternbach (1972).The skin conductance scores were then transformed with a statistical correction procedure proposed by Lykken, Rose, Luther, and Xlaley (1966),which corrects for individual differences in range of response. The resulting scores are analogous to a z-score transformation, with scores Mling between 0 and + 1.
Computations A 2 x 11 two-way mixed model ANOVA was computed for each measure (Factor A, high or low hypnotizability; Factor B, the induction period plus the 10 hypnotic items, the withm ~ a r i a b l e(Edwards, )~ 1979, pp, 132135). ?he procedures are described clearly in the physiograph manual, and a departmental technician had previously hained the senior author (L.M.S.) who made all of the conversions. Nevertheless, it should be pointed out that 10-second intervals m y be too short for obtainingvalid respiration rate measures. or perhaps a h electrodermaland EMC measures. Future investieton might wish to consider using longer intervals of measurement. ‘See Footnote 3. ‘SeeFootnote 3.
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C
FIG.I. High and low hypnotizable Ss’ heart rates at each item.
Heart rate was not significant for hypnotizability level (F = 2.50, df > .05) but was significant for periods (F =39.58,df = 10,200; p < .01) and the interaction (F = 9.11, df = 10,200; p < .01). Tukey’s test for the interaction (p < .05) showed that high hypnotizable Ss scored significantlyhigher than low hypnotizables on Items 1(hand lowering), 5 (arm rigid), 7 (age regression), and 9 (anosrnia for ammonia). Thus, the significant differences between high and low hypnotizable Ss were accounted for by the high hypnotizables scoring higher on four particular items rather than across all items (see Figure 1). Tukey’s test (p< .05) for item differences showed (a) that Item 1 (hand lowering) was higher than the induction, Items 6 (dream), 11 (negative visual hallucination), and 12 (posthypnotic amnesia); (b) that Item 5 (arm rigid) was higher than Items 6 (dream), 11 (negative visual hallucination) and 12 (posthypnotic amnesia); and (c) that Item 7 (age regression) was higher than Item 6 (dream). All other Tukey comparisons were not significant. Skin conductance results showed a main effect for periods (F =21.53, df = 10,200; p < .001) but not for hypnotizability (F < 1.0, df = 1,20) or the interaction (F C 1.0, df = 10,200). Tukey’s test showed that the lowest items, induction and dream (Item 6), did not differ, but both were significantly lower than Items 7 (age regression), 8 (arm immobilization), 9 (anosmia), 10 (voicehallucination), and 11 (negativevisual hallucination). = 1,20; p
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The EMG analysis showed a small but significant main effect for periods (F = 1.93, df = 10,200; p < .a), but not for hypnotizability level (F < 1.0) or the interaction (F < 1.0). Tukey’s post hocs on periods revealed only two significant differences between items: Item 18 (posthypnotic amnesia) was significantly higher than both the induction period and Item 11 (negative visual hallucination). Respiration rate showed a significant main effect for periods (F = 4.75, df = 10,200; p < .001) but not for hypnotizability (F = 1.43, df = 1,20; p > .a) or the interaction (F < 1.0). Tukey’s analyses showed Items 1 (hand lowering) and 7 (age regression) to be significantly higher than Items 12 (posthypnotic amnesia), 10 (hallucinated voice), 6 (dream), and 9 (anosmia for ammonia). Item 5 (arm rigidity) was significantly higher than Item 12 (posthypnotic amnesia). To evaluate the qualitative similarity of physiological responsiveness across items for high and low hypnotizable Ss, rank order coefficients (rhos) were computed. The 11 item means were ranked on each physiological meaSure for high and low hypnotizable Ss. The results showed significant rhos for each measure as follows: heart rate (rho = .635,p < .05); skin conductance (rho = .889, p < .01);EMG (rho = .N3,p < .05); and respiration rate (rho = .829, p < .01). Thus, the pattern of physiological responsiveness across items tended to be similar for high and low hypnotizable Ss.
DISCUSSION The results are discussed in light of the two predictions.
Instruction-Physiobgical Variation First, it was predicted that physiological responsiveness would differ depending upon the nature of the instructions (items). For example, physiological measurement after the induction, where Ss had been given many suggestions for relaxation, should be lower than measurements taken after requests for specific hypnotic performances, especially motor performances. The findings for all four physiological measures supported this prediction (i.e., all four main effects for periods were significant). The induction was the lowest or second to lowest m r e for EMG, heart rate, and skin conductance, a finding which was anticipated, since decreased arousal was expected following the induction relaxation instructions. The level of respiration rate, however, did not differ significantly from any of the other items, falling in between items that were high or low. Two motor items, hand lowering (Item 1) and arm rigidity (Item S), showed higher heart rate and respiration rate levels, consonant with the increases in muscle involvement and a sympathetic nervous system
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of testing. Item 8 (arm immobilization), the third motor item which did not differ from other items, requires increased muscular involvement only if S struggles to raise hidher relaxed arm. Low hypnotizable Ss presumably could raise their arms easily, while high hypnotizables may struggle and fail to lift their arms or sit passively and also fail to raise them. The finding that high hypnotizables differed from low hypnotizable Ss in increased heart rate on the first two motor items but not the third, suggests that some high hypnotizable Ss did not fight the challenge to lift their arm on Item 8 and, consequently, did not increase their muscular involvement significantly. (See, Martin and Venables [1980]and/or Stern, Ray, and Davis [ 19801for reviews of the meanings of the measures used.) Item 6 (dream) showed reduced arousal on heart rate, skin conductance, and respiration rate as would be expected from its content suggesting “falling asleep.” Item 7 (age regression) tended to show higher arousal on heart rate, skin conductance, and respiration rate as instructions led Ss to prepare for “sitting happily in school” - “in the second grade.” The results for Item 9 (anosmia for ammonia) make sense as well. Heart rate (in high hypnotizable Ss) and skin conductance tended to be high immediately after sniffing ammonia, and respiration rate was lowered as Ss tended to stop or reduce breathing immediately after sniffing. Heart seeing only two rate was lower for Item 11 (negative hallucination boxes when three are present) and Item 12 (posthypnotic amnesia) than for Items 1and 5 (the two motor items), probably reflecting the difference in muscle exertion on the motor items. So far, the patterns of physiological changes associated with item content generally make sense. However, Items 11 and 12 require closer examination, because their patterns are not so easily explained. Item 11 (negative hallucination) was low on both heart rate and EMG, but high on skin conductance. The combination of lowered heart rate and lowered E M G could reflect the low level of muscle activity during the time Ss are sitting quietIy and processing information. The higher skin conductance might reflect Ss’ alertness for informational cues. Item 12 (posthypnotic amnesia) was low on both heart rate and respiration rate, but high on EMG.The low heart rate could again reflect information processing as S tries to remember. The contradictory high EMC could be the result of Ss wrinkling their foreheads as they think, and the lower respiration rate could result from holding their breath while thinking. These post hoc explanations of the results for Items 11and 12,however, are only speculations. Future research should CarefuIly observe for specific movements, etc. which might atTect physiological responding. The reason for some discrepant results across different studies and different physiological measures might have also resulted from different task requirements across the studies. Other investigators (Barber, 1961, 1970; Crasilneck & Hall, 1959; Sarbin, 1956, 1973; Sarbin & Slagle, 1972) have pointed out that differ-
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ences in physiological responsiveness across hypnotic items do not support the notion that hypnosis is characterized by some unique physiological criteria. The present findings support the same position. Further, the significant rank order correlations between high and low hypnotizable Ss indicated the qualitative similarity of their physiological responsiveness to particular items on all four measures. Again, the findings do not support there being any special qualitative, physiological differences between high and low hypnotizable Ss.
Degree of Physiological Inoolvement The second prediction was that high hypnotizable Ss would show a greater degree of physiological responsiveness than low hypnotizable Ss. Three of the four physiological measures (skin conductance, EMG, respiration rate) did not support the prediction. Compared to low hypnotizable Ss, high hypnotizables showed significant differences only in heart rate 9 response levels on four items. Neither Barber and Hahn (1963)nor Bauer and McCanne (1980)found heart rate diEerences between their high hypnotizables and controls. Otherwise, their results conform to the present findings, showing that EMG, respiration, and skin conductance did not separate high and low hypnotizable Ss. The present study, combined with these two earlier studies, could be taken as evidence that the greater involvement of high hypnotizable Ss is not reflected in higher physiological involvement. A recent series of studies (Hughes br Bowers, 1987; Lichstein & Lipshitz, 1982; Rothmar, 1985),however, claimed that heart rate was the physiological variable most sensitive to imaging and that heart rate differences were found between high and low hypnotizable Ss on frightening images. The context of hypnosis versus actually being hypnotized, however, interacted in unclear ways. It was not clear whether just being in a context defined as a hypnotic experiment (and not being hypnotized) was sdicient to show the physiological differences. Nevertheless, when engaging in fearful imagery, high hypnotizable Ss in either case showed larger heart rate changes than did the low hypnotizables. For the present Ss, high hypnotizables showed higher heart rate on both of the active motor items -hand lowering (Item 1)and arm rigidity (Item 2). It would seem reasonable to assume that the increased involvement of the high hypnotizables as they "fight" their inability to prevent the response (arm lowering) or their inability to create the response (arm bending) would result in greater heart rate responses from greater muscle tensions. High hypnotizable Ss also showed higher heart rate responses on age regression (Item 7) and anosmia to ammonia (Item 9). Age regression tended to be an arousing item on skin conductance and respiration rate as well for all Ss. Thus, as high hypnotizable Ss were presumably experi'See Footnote 5
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encing (imagining) the regression more vividly than low hypnotizables, it is not too surprising that their heart rate responses would be higher. Explaining their higher heart rate on anosmia for ammonia is not as easy. If high hypnotizable Ss were presumably not experiencing the smell of ammonia as vividly as the low hypnotizables, why the increased indication of arousal? Perhaps the higher heart rate was a reflection of the high hypnotizable Ss expending more energy in creating ways to help bring about anosmia (i.e., ways to prevent the smell). In sum, the present results support the notion that physiological responsiveness is dependent on the type of suggestions during hypnosis and is similar in quality (and quantity for most suggestions) for both low and high hypnotizable Ss. Only differences in heart rate supported quantitative differences in physiological responsiveness between high and low hypnotizable Ss. The SHSS:C items were not designed to create highly arousing situations, however, as were the “frightening” scenes in the Hughes and Bowers’ (1987) study. Future research might result in clearer findings with items that are specifically constructed to create highly arousing situations.
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ReactivitC physiologique durant I’hypnose Laura M. Sturgis et Wdiam C. C a
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RisumC: Quatre mesuns physiobgiques: Clectmmyogramme, rythme mpiratoire, rythme cardiaque et conductance Clectrodermde, ont 6th enregistrtes chez 11 sujets fortement hypnotisables et 11 faiblement hypnotisables. Les deux hypotheses etaient: a) la riactivite physiobgique durant l’hypnoae variera en fonction der t k h a suggeria, b) les sujets fortemeat bypnotisables prtsenteront une riactivite physiolo@que plus blevbe a sujets faiblement hypnotisables. La premihre hypothhe a & t iconfirm& avec les que l quitre maures. Seul le rythme cnrdiaque a permis de confirmer la seconde h w t h t s e . Lea risultats sont discutes en fonction des deux hypothhses et de rechercher futures.
Respuestas fisid6giCzr durante la hipnosis Laura M. Sturgis y W
h C. Coe
Resumen: Se registram a t r o medidas 6siol6gicor: electrombgrama, r i b respiratorio, ritmo c d i a c o y cooducci60 de la piel, en 11 sujetor de aka y 11 de baja sugestibilidad hipn6tica. La hip6tesis sostenia que: a) la respuesta fisiol6gica durante la hipwsh iba a variar dependiendo de la naturalem de la tarea y, b) que los sujetar dtamente hip&bles iban a mortrar mayor mpwrta que los sujctos & baja hipnotizabilidad. La primera hip6tesis se mantuvo para todas Irr medidas, r6lo loa niveles de rihm cardiaco dieron r&n a la segunda hip6tesis. Se discuten lor resultados obtenidos con rapecto a la segunda h w t a i s asi como futuras invatigaciones.
International Journal of Clinical and Experimental Hypnosis Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/nhyp20
Physiological Responsiveness During Hypnosis a
Laura M. Sturgis & William C. Coe a
b
Honolulu, Hawaii
b
California State University , Fresno Published online: 31 Jan 2008.
To cite this article: Laura M. Sturgis & William C. Coe (1990) Physiological Responsiveness During Hypnosis, International Journal of Clinical and Experimental Hypnosis, 38:3, 196-207, DOI: 10.1080/00207149008414518 To link to this article: http://dx.doi.org/10.1080/00207149008414518
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Tln I n u r n u i o d ] o u r d of Clinicd and E x p m m c d H y p l w r r v 1880. Vd.LWIII. No. 3. 196-m
PHYSIOLOGICAL RESPONSIVENESS DURING HYPNOSIS’ LAURA M. STURGIS Honolulu. Harwii AVD
WILLIAM C.COE2
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California State University, F r e m
Abstract: 4 physiological measures -electromyogram, respiration rate, heart rate, and skin conductance - were recorded for 11 high and 11 low hypnotizable Ss. It was hypothesized (a) that physiological responsiveness during hypnosis would vary depending on the nature of the task instructions, and (b)that high hypnotizable Ss would show more physiological responsiveness tban low hypnotizable Ss. The first hypothesis was substantiated across all 4 measures. Only heart rate levels supported the second hypothesis. The results are discussed as they relate to the 2 hypotheses and to future research.
Research attempting to uncover various physiological indicants of hypnosis (e.g., basal metabolic rate, blood volume, respiration rate, electroencephalograph [EEG], peripheral blood flow, heart rate, skin conductance, muscle tension - electromyograph [EMG], etc.) has been reviewed earlier by a number of investigators (Barber, 1961, 1970: Crasilneck & Hall, 1959; Edmonston, 1979; Levitt & Brady, 1963;Sarbin, 1956, 1973; Sarbin & Slagle, 1972; Spanos, 1982). The general conclusion has been that the intensity and duration of physiological responses in hypnosis vary in much the same way as they do outside of hypnosis. In fact, Damaser, Shor, and M. T. Orne (1963)found that simulating Ss showed similar physiological changes as did real Ss. demonstrating that “suggested” versus “requested emotions had no unique physiological pattern. It therefore appears that reliable physiological correlates of hypnotizability have not been demonstrated, nor can hypnosis be viewed as accompanied by unique, physiological properties (Barber. 1961; Spanos, 1982). The nature of the hypnotic induction, prior hypnotic experience, and specific task instructions, however, are some of the variables that have helped to account for the otherwise confusing discrepancies in the literature. For example, when Ss took literally the typical suggestions of relaxation and drowsiness in hypnotic inductions, their skin conductance declined (Barber & Hahn, 1963; Bauer & McCanne, 1930; Estabrooks, Manuscript submitted March 28.1988; find revision received December 26, 1989. ‘The study met in part the senior author‘s requirements for the Masters of Arts degree at California State University, Fresno. ‘Reprint requests should be addressed to William C. Coe. Ph. D.. Department of Psychology, California State University. Fresno. CA 93740-0011.
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1930; Levine, 1930). Conversely, skin conductance levels did not change for Ss who had had prior hypnotic experience, presumably because they had learned to remain alert and prepared for upcoming task instructions (Barber & Coules, 1959). Davis and Kantor (1935) also demonstrated the differential effects of instructions on skin conductance by comparing active and quiescent hypnotic states. With relaxation and sleep instructions, conductance decreased, resembling conductance levels achieved during typical sleep. During the active condition, conductance levels resembled those seen when awake. The degree of organismic involvement in the role of hypnotic S is the focus of the present study. The present authors would predict that highly responsive hypnotic Ss become more organismically involved in hypnosis than do less responsive S s and are thereby more convincing S s to themselves as well as to others (e.g., Coe & Sarbin, 1977; Sarbin & Coe, 1972, 1979). Also, in keeping with our emphasis on the interaction of environmental events and S variables, it is predicted that Ss’ physiological activity would covary with the nature of the hypnotist’s instructions (suggestions). For example, the suggestions for relaxation, etc. during the induction period should result in less physiological arousal than other suggestions which ask for specific responses.
METHOD Subjects
Two hundred sixty introductory psychology students were screened using a taped administration of the Harvard Group Scale of Hypnotic Susceptibility, Form A (HGSHS:A) of Shor and E. C. Orne (1962).Thirty Ss were selected initially as highs (score of 9 or more) or lows (score of 3 or less). The find samples after screening for reliability on the Stanford Hypnotic Susceptibility Scale, Form C (SHSSC) Weitzenhoffer and Hilgard (1962) consisted of 11 high hypnotizables (9 female, 2 male) and 11 low hypnotizables (8 female, 3 male). Their mean age was 19.5 years. All participated for credit in an introductory psychology course. Apparatus3
The Narco Bio-Systems Physiograph P M P 4 was used to monitor Ss’ physiological responses during the hypnotic session. The speed of the ’Schematic diagrams of the N m B i o Systems Physiograph and the electmmyograph
(EMC)equipment may be obtained from the National AuxiliPry Publications Service (NAPS). A table of the means and standard deviations for each physiologicpi measure on the 11 items may also be obtained from NAPS. For 5 pages order document No. 04776 from ASIS-NAPS, do Microfiche Publications, P. 0. Box 3513, Grand Central Station. New York, NY 101633513. Remit in advance in U.S. funds only $7.73, for photocopies or $4.00 for microfiche and make checks payable to Microfiche Publications NAPS. Outside the United States and Canada, add postage of $4.50 for a photocopy and S1.50 for a fiche. There is a $15.00 invoicing fee for orders not prepaid.
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physiograph paper was set at 2 cm/second, and each physiological measure was recorded simultaneously by a separate pen on the same sheet of Paper. Three EMG surface electrodes filled with conductive cream were placed over S’s frontalis muscle, approximately 3.8 cm above the eyebrows, with the ground electrode located in the center. All three electrodes were held in place by an adjustable rubber headband. The electrodes were plugged into one of two EEGlEMG NB-132 Preamplifiers which fed into Channel 2 of an EEG/EMG Filter Module NB-122 of the Narco EEG/EMG Biofeedback System. The filter module was set for a range of 100 Hz to 500 Hz. An EEG/EMG Calibrator NB-192, which injected a 200-Hz, 12-microvolt signal, was attached to the other preamplifier which fed into Channel 1 of the filter module. A switch on the filter module made it possible to shift &om Channel 1 to Channel 2, so that the calibration of the equipment could be checked or changed during the session. The feedback signal output of the filter module was connected to the auxiliary input of a Type 7070 Channel Amplifier in the Physiograph and recorded by Pen 1. The EMG amplitude was indicated on the graph by the position of the recording pen. Center position represented a 1 2 - k ~EMG signal, and each centimeter square represented a change of 2kv. Respiration rate was measured using a Bellows Pneumograph attached to an ESG Coupler Type 7211, which measures changes in air pressure, producing a pen movement on the graph. The monitor output of the ESC coupler was connected to the auxiliary input of the channel amplifier and the signal was recorded. The paper speed of 2 cmlsecond allowed for clear discrimination of the respiration wave form. Heart rate was monitored using a Photoelectric Pulse Transducer Type 323 fastened to the thumb of S’s nonpreferred hand and attached to a Transducer Coupler Type 7173. The transducer fed directly into Channel Amplifier 2 and was also coupled with a Biotachometer Type 7302 which fed into Channel Amplifier 3. Heart rate was measured in beats per minute. The actual pulse as viewed on the paper served as the dependent measure. Skin resistance was measured using two Narco soft lead skin resistance finger electrodes. After normal cleaning and without any electrolyte, the electrodes were fastened to S’s index and middle fingers over the proximal phalanx of the nonpreferred hand. The electrodes were attached to a GSR Coupler Type 7175, which fed into the Channel 4 amplifier with the signal being recorded. The GSR was set for direct coupling so that the actual skin resistance in kilohms was recorded. The coupler was calibrated for 10 Kilohmskm. on the vertical axis and 2 cmlsecond on the horizontal axis.
Procedure The Ss were randomly assigned to experimental sessions. The S was escorted into the experimental room, introduced to the two Es, and
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instructed to sit in a large, reclining armchair. The nature of the study was explained as an investigation of physiological responsiveness during hypnosis. After the instruments were attached, S was requested to sit quietly while base rate measures were taken and channel adjustments for response range were made. After base rates, E 1‘ began administration of SHSS:C. The E 2 (L.M.S.) attended to the physiograph in an adjacent room and received visual and auditory feedback of the session via a three-camera, remote control, video-audio system. Any irregularities that might S e c t the physiological measures could be recorded (e.g.. movement of S’s nondominant hand, rocking, moving the head, etc.). Fortunately, no irregularities of any magnitude were observed. The hypnotist wore a miniature radio receiver so that E 2 could communicate without disturbing S. The E 2 monitoring the physiograph delineated each of the 12 periods precisely by placing a mark on the recording paper at the beginning and end of each 10-second interval. Items 2 and 3 (moving hand apart and mosquito hallucination, respectively) were deleted from SHSS:C because of the possibility of S dislodging the skin resistance electrodes and heart rate monitor attached to the nonpreferred hand. Directions for Items 1, 5, and 8 were modified to the use of S’s dominant hand in order to avoid moving the electrodes on the nonpreferred hand. Only the data from Ss who demonstrated high consistency between the two hypnosis scales (HGSHS:A and SHSS:C) were analyzed. High scorers on HGSHS:A had to pass 8 of 10 remaining SHSS:C items; lows could pass no more than 4 SHSS:C items. Twenty-two out of 30 Ss tested met these criteria.
RESULTS Physiological Scores Each physiological measure was computed from 10-second intervals. The intervals were selected with the intent of capturing SP responses at points of maximum involvement, either to relax or to become alert for tasks. The 12 intervds were: (1) base rate - the 10 seconds before immediately following the the start of the induction; (2) induction deepening count fiom 1 to 20; (3) Item 1 (hand lowering) during the prescribed l0-second scoring period; (4) Item 4 (taste hallucination) directly after the first query for sour taste; (5) Item 5 (arm rigidity) during the l0-second scoring period; (6) Item 6 (dream) following the initial 60 seconds of the dream period; (7) Item 7 (age regression) immediately following the count to “2” for regression to the second grade, but before S was questioned, since any verbal activity would confound EMC scores; (8) Item 8 (arm immobilization - left arm) during the 10-second scoring period; (9) Item 9 (anosmia to ammonia) immediately after the initial
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‘We wish to thank Laura Kuhn for assisting as hypnotist.
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sniff of amnonia; (10) Item 10 (hallucinated voice) after the hypnotist’s statement, “There’s the first question”; (11)Item 11(negative visiial hallucination)just after S was told to open eyes and look at the two boxes, but before the questioning about what was seen; (12) Item 12 (posthypnotic amnesia) during the first recall period. The pen tracings for each measure were transformed to the data. Heart rate and respiration rate were computed by counting the number of obvious humps (each heart beat or respiratory cycle) traced during the l0-second period. The result was multiplied by 6 to convert to beats per minute. The EMC readings were converted by adding the p v levels at each 1-second interval during the 10-second time period, then dividing by 10 to obtain the mean for each period. Skin conductance level was based on the mean calculated from 10 one-second samples.’ The base rate measures were used to compare any changes during the induction-relaxation period and each of the selected scoring periods. None of the base rate measures differed significantly between high and low hypnotizable Ss (all t’s < 1.0). Accordingly, Ss’ means of their 11 raw physiological scores for EMG, respiration rate, and heart rate, were subtracted from their mean base rate scores. Constants were then added to difference scores in order to prevent negative scores.’ Specific difference scores for each measure were computed as follows: (a) heart rate = mean beats/minute/period (item), minus basal rate, plus 15. (Thus, 15 equals no change from basal rate.) (b) EMG = mean mv/crn2/period (item), minus basal rate, plus 16. (c) respiration rate = mean cycles/minute/period (item), minus basal rate, plus 10. (d) skin resistance (kilohms/cm*)was transformed into skin conductance (micromhodcm’), its reciprocal, the preferred measure according to Greenfield and Sternbach (1972).The skin conductance scores were then transformed with a statistical correction procedure proposed by Lykken, Rose, Luther, and Xlaley (1966),which corrects for individual differences in range of response. The resulting scores are analogous to a z-score transformation, with scores Mling between 0 and + 1.
Computations A 2 x 11 two-way mixed model ANOVA was computed for each measure (Factor A, high or low hypnotizability; Factor B, the induction period plus the 10 hypnotic items, the withm ~ a r i a b l e(Edwards, )~ 1979, pp, 132135). ?he procedures are described clearly in the physiograph manual, and a departmental technician had previously hained the senior author (L.M.S.) who made all of the conversions. Nevertheless, it should be pointed out that 10-second intervals m y be too short for obtainingvalid respiration rate measures. or perhaps a h electrodermaland EMC measures. Future investieton might wish to consider using longer intervals of measurement. ‘See Footnote 3. ‘SeeFootnote 3.
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C
FIG.I. High and low hypnotizable Ss’ heart rates at each item.
Heart rate was not significant for hypnotizability level (F = 2.50, df > .05) but was significant for periods (F =39.58,df = 10,200; p < .01) and the interaction (F = 9.11, df = 10,200; p < .01). Tukey’s test for the interaction (p < .05) showed that high hypnotizable Ss scored significantlyhigher than low hypnotizables on Items 1(hand lowering), 5 (arm rigid), 7 (age regression), and 9 (anosrnia for ammonia). Thus, the significant differences between high and low hypnotizable Ss were accounted for by the high hypnotizables scoring higher on four particular items rather than across all items (see Figure 1). Tukey’s test (p< .05) for item differences showed (a) that Item 1 (hand lowering) was higher than the induction, Items 6 (dream), 11 (negative visual hallucination), and 12 (posthypnotic amnesia); (b) that Item 5 (arm rigid) was higher than Items 6 (dream), 11 (negative visual hallucination) and 12 (posthypnotic amnesia); and (c) that Item 7 (age regression) was higher than Item 6 (dream). All other Tukey comparisons were not significant. Skin conductance results showed a main effect for periods (F =21.53, df = 10,200; p < .001) but not for hypnotizability (F < 1.0, df = 1,20) or the interaction (F C 1.0, df = 10,200). Tukey’s test showed that the lowest items, induction and dream (Item 6), did not differ, but both were significantly lower than Items 7 (age regression), 8 (arm immobilization), 9 (anosmia), 10 (voicehallucination), and 11 (negativevisual hallucination). = 1,20; p
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The EMG analysis showed a small but significant main effect for periods (F = 1.93, df = 10,200; p < .a), but not for hypnotizability level (F < 1.0) or the interaction (F < 1.0). Tukey’s post hocs on periods revealed only two significant differences between items: Item 18 (posthypnotic amnesia) was significantly higher than both the induction period and Item 11 (negative visual hallucination). Respiration rate showed a significant main effect for periods (F = 4.75, df = 10,200; p < .001) but not for hypnotizability (F = 1.43, df = 1,20; p > .a) or the interaction (F < 1.0). Tukey’s analyses showed Items 1 (hand lowering) and 7 (age regression) to be significantly higher than Items 12 (posthypnotic amnesia), 10 (hallucinated voice), 6 (dream), and 9 (anosmia for ammonia). Item 5 (arm rigidity) was significantly higher than Item 12 (posthypnotic amnesia). To evaluate the qualitative similarity of physiological responsiveness across items for high and low hypnotizable Ss, rank order coefficients (rhos) were computed. The 11 item means were ranked on each physiological meaSure for high and low hypnotizable Ss. The results showed significant rhos for each measure as follows: heart rate (rho = .635,p < .05); skin conductance (rho = .889, p < .01);EMG (rho = .N3,p < .05); and respiration rate (rho = .829, p < .01). Thus, the pattern of physiological responsiveness across items tended to be similar for high and low hypnotizable Ss.
DISCUSSION The results are discussed in light of the two predictions.
Instruction-Physiobgical Variation First, it was predicted that physiological responsiveness would differ depending upon the nature of the instructions (items). For example, physiological measurement after the induction, where Ss had been given many suggestions for relaxation, should be lower than measurements taken after requests for specific hypnotic performances, especially motor performances. The findings for all four physiological measures supported this prediction (i.e., all four main effects for periods were significant). The induction was the lowest or second to lowest m r e for EMG, heart rate, and skin conductance, a finding which was anticipated, since decreased arousal was expected following the induction relaxation instructions. The level of respiration rate, however, did not differ significantly from any of the other items, falling in between items that were high or low. Two motor items, hand lowering (Item 1) and arm rigidity (Item S), showed higher heart rate and respiration rate levels, consonant with the increases in muscle involvement and a sympathetic nervous system
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of testing. Item 8 (arm immobilization), the third motor item which did not differ from other items, requires increased muscular involvement only if S struggles to raise hidher relaxed arm. Low hypnotizable Ss presumably could raise their arms easily, while high hypnotizables may struggle and fail to lift their arms or sit passively and also fail to raise them. The finding that high hypnotizables differed from low hypnotizable Ss in increased heart rate on the first two motor items but not the third, suggests that some high hypnotizable Ss did not fight the challenge to lift their arm on Item 8 and, consequently, did not increase their muscular involvement significantly. (See, Martin and Venables [1980]and/or Stern, Ray, and Davis [ 19801for reviews of the meanings of the measures used.) Item 6 (dream) showed reduced arousal on heart rate, skin conductance, and respiration rate as would be expected from its content suggesting “falling asleep.” Item 7 (age regression) tended to show higher arousal on heart rate, skin conductance, and respiration rate as instructions led Ss to prepare for “sitting happily in school” - “in the second grade.” The results for Item 9 (anosmia for ammonia) make sense as well. Heart rate (in high hypnotizable Ss) and skin conductance tended to be high immediately after sniffing ammonia, and respiration rate was lowered as Ss tended to stop or reduce breathing immediately after sniffing. Heart seeing only two rate was lower for Item 11 (negative hallucination boxes when three are present) and Item 12 (posthypnotic amnesia) than for Items 1and 5 (the two motor items), probably reflecting the difference in muscle exertion on the motor items. So far, the patterns of physiological changes associated with item content generally make sense. However, Items 11 and 12 require closer examination, because their patterns are not so easily explained. Item 11 (negative hallucination) was low on both heart rate and EMG, but high on skin conductance. The combination of lowered heart rate and lowered E M G could reflect the low level of muscle activity during the time Ss are sitting quietIy and processing information. The higher skin conductance might reflect Ss’ alertness for informational cues. Item 12 (posthypnotic amnesia) was low on both heart rate and respiration rate, but high on EMG.The low heart rate could again reflect information processing as S tries to remember. The contradictory high EMC could be the result of Ss wrinkling their foreheads as they think, and the lower respiration rate could result from holding their breath while thinking. These post hoc explanations of the results for Items 11and 12,however, are only speculations. Future research should CarefuIly observe for specific movements, etc. which might atTect physiological responding. The reason for some discrepant results across different studies and different physiological measures might have also resulted from different task requirements across the studies. Other investigators (Barber, 1961, 1970; Crasilneck & Hall, 1959; Sarbin, 1956, 1973; Sarbin & Slagle, 1972) have pointed out that differ-
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ences in physiological responsiveness across hypnotic items do not support the notion that hypnosis is characterized by some unique physiological criteria. The present findings support the same position. Further, the significant rank order correlations between high and low hypnotizable Ss indicated the qualitative similarity of their physiological responsiveness to particular items on all four measures. Again, the findings do not support there being any special qualitative, physiological differences between high and low hypnotizable Ss.
Degree of Physiological Inoolvement The second prediction was that high hypnotizable Ss would show a greater degree of physiological responsiveness than low hypnotizable Ss. Three of the four physiological measures (skin conductance, EMG, respiration rate) did not support the prediction. Compared to low hypnotizable Ss, high hypnotizables showed significant differences only in heart rate 9 response levels on four items. Neither Barber and Hahn (1963)nor Bauer and McCanne (1980)found heart rate diEerences between their high hypnotizables and controls. Otherwise, their results conform to the present findings, showing that EMG, respiration, and skin conductance did not separate high and low hypnotizable Ss. The present study, combined with these two earlier studies, could be taken as evidence that the greater involvement of high hypnotizable Ss is not reflected in higher physiological involvement. A recent series of studies (Hughes br Bowers, 1987; Lichstein & Lipshitz, 1982; Rothmar, 1985),however, claimed that heart rate was the physiological variable most sensitive to imaging and that heart rate differences were found between high and low hypnotizable Ss on frightening images. The context of hypnosis versus actually being hypnotized, however, interacted in unclear ways. It was not clear whether just being in a context defined as a hypnotic experiment (and not being hypnotized) was sdicient to show the physiological differences. Nevertheless, when engaging in fearful imagery, high hypnotizable Ss in either case showed larger heart rate changes than did the low hypnotizables. For the present Ss, high hypnotizables showed higher heart rate on both of the active motor items -hand lowering (Item 1)and arm rigidity (Item 2). It would seem reasonable to assume that the increased involvement of the high hypnotizables as they "fight" their inability to prevent the response (arm lowering) or their inability to create the response (arm bending) would result in greater heart rate responses from greater muscle tensions. High hypnotizable Ss also showed higher heart rate responses on age regression (Item 7) and anosmia to ammonia (Item 9). Age regression tended to be an arousing item on skin conductance and respiration rate as well for all Ss. Thus, as high hypnotizable Ss were presumably experi'See Footnote 5
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encing (imagining) the regression more vividly than low hypnotizables, it is not too surprising that their heart rate responses would be higher. Explaining their higher heart rate on anosmia for ammonia is not as easy. If high hypnotizable Ss were presumably not experiencing the smell of ammonia as vividly as the low hypnotizables, why the increased indication of arousal? Perhaps the higher heart rate was a reflection of the high hypnotizable Ss expending more energy in creating ways to help bring about anosmia (i.e., ways to prevent the smell). In sum, the present results support the notion that physiological responsiveness is dependent on the type of suggestions during hypnosis and is similar in quality (and quantity for most suggestions) for both low and high hypnotizable Ss. Only differences in heart rate supported quantitative differences in physiological responsiveness between high and low hypnotizable Ss. The SHSS:C items were not designed to create highly arousing situations, however, as were the “frightening” scenes in the Hughes and Bowers’ (1987) study. Future research might result in clearer findings with items that are specifically constructed to create highly arousing situations.
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PHYSIOLOGICAL RESPONSIVENESS DURING HYPNOSIS
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ReactivitC physiologique durant I’hypnose Laura M. Sturgis et Wdiam C. C a
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RisumC: Quatre mesuns physiobgiques: Clectmmyogramme, rythme mpiratoire, rythme cardiaque et conductance Clectrodermde, ont 6th enregistrtes chez 11 sujets fortement hypnotisables et 11 faiblement hypnotisables. Les deux hypotheses etaient: a) la riactivite physiobgique durant l’hypnoae variera en fonction der t k h a suggeria, b) les sujets fortemeat bypnotisables prtsenteront une riactivite physiolo@que plus blevbe a sujets faiblement hypnotisables. La premihre hypothhe a & t iconfirm& avec les que l quitre maures. Seul le rythme cnrdiaque a permis de confirmer la seconde h w t h t s e . Lea risultats sont discutes en fonction des deux hypothhses et de rechercher futures.
Respuestas fisid6giCzr durante la hipnosis Laura M. Sturgis y W
h C. Coe
Resumen: Se registram a t r o medidas 6siol6gicor: electrombgrama, r i b respiratorio, ritmo c d i a c o y cooducci60 de la piel, en 11 sujetor de aka y 11 de baja sugestibilidad hipn6tica. La hip6tesis sostenia que: a) la respuesta fisiol6gica durante la hipwsh iba a variar dependiendo de la naturalem de la tarea y, b) que los sujetar dtamente hip&bles iban a mortrar mayor mpwrta que los sujctos & baja hipnotizabilidad. La primera hip6tesis se mantuvo para todas Irr medidas, r6lo loa niveles de rihm cardiaco dieron r&n a la segunda hip6tesis. Se discuten lor resultados obtenidos con rapecto a la segunda h w t a i s asi como futuras invatigaciones.
