1996
Dane, Joseph R. (1996). Hypnosis for pain and neuromuscular rehabilitation with multiple sclerosis: Case summary, literature review, and analysis of outcomes. International Journal of Clinical and Experimental Hypnosis, 44 (3), 208-231.
Videotaped treatment sessions in conjunction with 1-month, 1-year, and 8-year follow-up allow a unique level of analysis in a case study of hypnotic treatment for pain and neuromuscular rehabilitation with multiple sclerosis (MS). Preparatory psychotherapy was necessary to reduce the patient’s massive denial before she could actively participate in hypnosis. Subsequent hypnotic imagery and posthypnotic suggestion were accompanied by significantly improved control of pain, sitting balance, and diplopia (double vision), and a return to ambulatory capacity within 2 weeks of beginning treatment with hypnosis. Evidence regarding efficacy of hypnotic strategies included (a) direct temporal correlations between varying levels of pain relief and ambulatory capacity and the use versus nonuse of hypnotic strategies, (b) the absence of pharmacological explanations, and (c) the ongoing presence of other MS-related symptoms that remained unaltered. In conjunction with existing literature on hypnosis and neuromuscular conditions, results of this case study strongly suggest the need for more detailed and more physiologically based studies of the phenomena involved. – Journal Abstract
1995
Crawford, Helen J.; Kapelis, Lia; Harrison, David W. (1995). Visual field asymmetry in facial affect perception: Moderating effects of hypnosis, hypnotic susceptibility level, absorption, and sustained attentional abilities. International Journal of Neuroscience, 82 (n1-2), 11-23.
Effects of hypnotic level, affect valence and cerebral asymmetry on reaction time (RT) in the discrimination of Ekman and Friesent (1978) stimuli of angry and happy faces were studied in counterbalanced conditions of waking and hypnosis. Assessed previously on two hypnotic susceptibility scales (Harvard Group Scale of Hypnotic Susceptibility; Stanford Hypnotic Susceptibility Scale, Form C (SHSS:C)], non-depressed subjects were 16 low (0-4 SHSS:C) and 17 highly (10-12 SHSS:C) hypnotizable, right- handed college students. Subjects were required to identify affect of faces, presented tachistoscopically to left (LVF) or right (RVF) visual fields, by using a forced-choice RT paradigm. Highs were significantly faster than lows in angry and happy affect recognition. Hypnosis had no significant effects. For highs only, angry emotional valence was identified faster when presented to the right hemisphere (LVF), but there were no significant hemispheric effects for happy emotional valence. For lows there were no hemispheric differences. Gender was a nonsignificant factor. Significant correlations showed that faster reaction times to angry and happy stimuli, in both LVF and RVF in waking and hypnosis, were obtained by subjects who reported more deeply absorbed and extremely focused and sustained attention on the Tellegen (1982) Absorption Scale and a subscale of the Differential Attentional Processes Inventory (Grumbles & Crawford, 1981). Vividness of Visual Imagery Questionnaire (Marks, 1973) and Affect Intensity Measure (Larsen, 1985), in general, did not correlate with RTs. The potential role of the fronto-limbic attentional system in the recognition of external visual sensory affect is discussed.
1993
Atkinson, Richard P. (1993, October). Shifts in Muller-Lyer Illusion difference thresholds: Are high hypnotizables more sensitive than lows in hypnosis?. [Paper] Presented at the annual meeting of the Society for Clinical and Experimental Hypnosis, Arlington Heights, IL
NOTES
Refers to Wallace (1979) finding that hypnotizability correlates with afterimage persistence. Atkinson showed highs perform better than lows in perceptual tasks in hypnosis only. Also studies indicate highs are more susceptible to illusions. Our study showed difference in threshold and point of subjective equality for highs and lows.
32 undergraduates had Harvard and Group Stanford Form C, were 9-12 or 0-3 on both scales. Counterbalanced conditions of waking and hypnosis. Used computer monitor to compare length of lines. Waking condition Ss had to close eyes for 15 minutes before the trials, same length of time as for hypnosis condition.
Significant interaction between hypnotizability and sessions was observed: highs had significantly decreased difference thresholds in hypnosis compared to waking, and significantly decreased difference thresholds compared to lows in hypnosis. Thus they had greater sensitivity than lows.
The point of subjective equality ANOVA did not yield significant effects.
Highs show higher sensitivity to illusion in hypnosis than in waking, and more than the lows.
McCormack, K.; Gruzelier, J. (1993). Cerebral asymmetry and hypnosis: A signal-detection analysis of divided visual field stimulation. Journal of Abnormal Psychology, 102 (3), 352-357.
These authors studied the effect of hypnosis on brightness discrimination with the aid of a signal-detection procedure in three sessions, the second with hypnosis. After two or three training sessions with hypnosis, which involved listening to a taped hypnotic relaxation induction, subjects were subdivided into high- and medium-susceptible groups on the basis of a ‘scale inspired by the Stanford Scales.’ High-susceptible subjects were found to show increases in perceptual sensitivity in the left visual field (right hemisphere) with hypnosis, whereas medium-susceptible subjects showed bilateral enhancements. The attitudes, or criterion set by the subjects remained invariant in both groups across the three sessions. It was concluded that the results provided evidence of altered brain function with hypnosis and an association of focal right hemispheric changes with high susceptibility, and through the invariance of motivational factors, failed to support the attribution of perceptual changes to attitudinal, non-state factors.
1992
Atkinson, Richard P.; Crawford, Helen J. (1992). Individual differences in afterimage persistence: Relationships to hypnotic susceptibility and visuospatial skills. American Journal of Psychology, 105 (4), 527-539.
To investigate the moderating role of individual differences in hypnotic susceptibility and visuospatial skills on afterimage persistence, we presented a codable (cross) flash of light to 40 men and 46 women who had been dark adapted for 20 minutes. In an unrelated classroom setting, subjects had previously been given two standardized scales of hypnotic susceptibility (Harvard Group Scale of Hypnotic Susceptibility, Shor & Orne, 1962; Group Stanford Hypnotic Susceptibility Scale, Form C, Crawford & Allen, 1982) and the Mental Rotations Test (Vandenberg & Kuse, 1978). The first afterimage interval and the afterimage duration correlated significantly with hypnotic responsiveness, supporting Wallace (1979), but did not show the anticipated relationships with mental rotation visuospatial skills. Individuals in the high hypnotizable group had (a) significantly longer afterimage intervals between its first appearance and first disappearance than did those in low groups, but those in medium groups did not differ significantly from the other groups. Discriminant analysis using the afterimage persistence measures classified correctly 65.2% of high hypnotizables, 37.5% of medium hypnotizables, and 54.8% of low hypnotizables. Hypothesized cognitive skills that assist in the maintenance of afterimages and underlie hypnotic susceptibility include abilities to maintain focused attention and resist distractions over time and to maintain vivid visual images.
NOTES
Because there is no apparent evidence for physiological differences of the visual system between low and high hypnotizables (e.g., Wallace, 1979), cognitive factors are suggested as possible moderators of afterimage persistence.
“Hypnotic susceptibility per se is not the moderator of afterimage duration. Rather, we argue that hypnotic susceptibility represents a constellation of underlying cognitive skills (e.g., for reviews, see Crawford, 1989; Kihlstrom, 1985) that assist an individual to respond to hypnotic suggestions as well as assist in the persistence of afterimages by interacting with more primary casual mechanisms that are physiological in origin. These cognitive skills are thought to include the abilities to focus attention selectively upon both external stimuli and internally generated images, to maintain vivid visual images, to sustain attention over time and remain absorbed in the experience at hand, and to resist distractions. The relationships between these cognitive skills and hypnotic susceptibility are reported in a large body of literature (e.g., Crawford, 1982, 1989; Crawford et al., 1991; Crawford & Grumbles, 1988; Finke & Macdonald, 1978; Grumbles & Crawford, 1981; Mitchell, 1970; Tellegen & Atkinson, 1974)….
“Sustained and selective attention without interference from extraneous stimuli plays an important role in hypnosis. Individuals who are responsive to hypnosis demonstrate greater skills in extremely focused and sustained attention (e.g., Crawford et al., 1991; Tellegen & Atkinson, 1974). Electrophysiological research had found that high hypnotizables often generate substantially more theta electroencephalogram (EEG) power than do low hypnotizables (e.g., Crawford 1990, 1991; Crawford & Gruzelier, 1992; Sabourin, Cutcomb, Crawford, & Pribam, 1990). Such a relationship may be interpreted as further evidence of greater attentional skills in highs, because certain theta waves have been correlated with enhanced problem solving and attentional task performance (e.g., Crawford & Gruzelier, 1992; Schacter, 1977)….
“Hypnosis is seen often as a condition of amplified attention, where attention can be either more focused or diffuse dependent upon set (e.g., Krippner & Binder, 1974). Increases in vigilant performance during hypnosis have been reported, albeit inconsistently (e.g., Barabasz, 1980; Fehr & Stern, 1967; Kissen, Reifler, & Thaler, 1964; Smyth & Lowy, 1983). Fehr and Stern’s results suggest that hypnotized subjects devote more attention to a primary task with less available attentional resources for a secondary task. Hypnosis has been found to have an enhancing effect on the imaginal processing of information-to-be-remembered that consists of literal or untransformed representations of pictorial or nonverbal information for high but not low hypnotizables (Crawford & Allen, 1983; Crawford, Nomura, & Slater, 1983; Crawford, Wallace, Nomura, & Slater, 1986). This may possibly be the result of increased attention and/or shifts in cognitive strategies. Supportive of the hypothesis that sustained attention can be enhanced during hypnosis, Atkinson (1991) recently found that high but not low hypnotizables report significantly more persistent afterimages in hypnosis than in waking.
“Although we have argued for a cognitive explanation for individual differences in afterimage persistence and their possible relationship to hypnotic susceptibility and sustained attentional abilities, as has Wallace (1979, 1990), we must point out the possibility that high hypnotizables may be more suggestible to imagery instructions or more willing to discuss or experience imagery than low hypnotizables, particularly in the context of hypnosis and hypnotic susceptibility testing (e.g., Zamansky, Scharf, & Brightbill, 1964). A contextual account of the longstanding relationship between hypnotic susceptibility and absorption was raised by Council, Kirsch, and Hafner (1986), but was not supported by two independent, and more methodologically sound, studies reported by Nadon, Hoyt, Register, and Kihlstrom (1991). The context of hypnosis was not an issue in the present study, because none of the subjects was aware of the investigated relationship between afterimage persistence and hypnotic susceptibility at the time of recruitment or participation” (pp. 533-535).
Kay, L. M. (1992, October). The effects of hypnosis, relaxation, and suggestion on visual acuity (Dissertation, California School of Professional Psychology, San Diego). Dissertation Abstracts International, 53 (4), 2065-B. (Order No. DA 9221587)
Evaluated the relative efficacy of several aspects of the hypnotic process on facilitating change in hypnotic state-dependent visual acuity in myopic student subjects. Five conditions included hypnosis with suggestions, neutral hypnosis, nonhypnotic suggestion, progressive relaxation, and a control (comedy). Visual acuity was assessed as baseline (a task-motivational situation where they were to try to see as well as possible) and after the experimental condition. Results found that hypnosis facilitated a significant improvement in visual acuity (p = .002), although no differences were found in the other conditions” (p. 2065).
Spanos, Nicholas P.; Burgess, C. A.; Cross, P. A.; MacLeod, G. (1992). Hypnosis, reporting bias, and suggested negative hallucinations. Journal of Abnormal Psychology, 101, 192-199.
Examined the role of reporting bias in hypnotic negative hallucinations by using a paradigm in which reporting bias was assessed independently of perceptual change. In Experiment 1, highly hypnotizable subjects reported significant loudness reductions when tested for hypnotic deafness. Later, however, these subjects biased their reported loudness reductions in the absence of perceptual change, and their reporting bias scores were almost as large as their hypnotic deafness reports. Subjects also biased their ratings of strategy use. In Experiment 2, ratings of blindness given in response to a hypnotic negative visual hallucination suggestion were significantly correlated with reporting bias scores obtained in this paradigm. Although hypnotic blindness and hypnotic deafness correlated significantly, the partial correlation between these variables was nonsignificant when reporting bias scores were statistically controlled. Results are used to support a skeptical view of hypnotic response as being based on compliance.
1991
Marzi, C. A.; Bisiacchi, P.; Nicoletti, R. (1991). Is interhemispheric transfer of visuomotor information asymmetric? Evidence from a meta-analysis. Neuropsychologia, 29, 1163-1177.
Using a meta-analytic procedure we have analysed 16 studies employing a simple unimanual reaction time (RT) paradigm and lateralized visual stimuli to provide an estimate of interhemispheric transfer time in normal right-handed subjects. We found a significant overall RT advantage of the left visual field over the right and of the right hand over the left. These asymmetries can be explained by a superiority of the right hemisphere for the detection of simple visual stimuli and by a corresponding superiority of the left hemisphere for the execution of the manual response, respectively. Alternatively, they may be interpreted as related to an asymmetry of interhemispheric transmission of visuomotor information, with transfer from the right hemisphere (side of stimulus entry) to the left (side of response generation) faster than in the reverse direction. Although a direct test of these hypotheses is still lacking, we think that the evidence available is more in keeping with the latter possibility.
1990
Wallace, Benjamin (1990). Hypnotizability and the modification of cognitive search strategies. International Journal of Clinical and Experimental Hypnosis, 38, 60-69.
An experiment was conducted to determine if Ss judged to be low in hypnotizability could be taught the efficient search strategies used by high hypnotizable Ss in the performance of a cognitive search task. Ss were requested to find objects embedded within a variety of pictorial scenes. High hypnotizable Ss were found to be more adept than low hypnotizables at finding more objects correctly. When low hypnotizable Ss were taught the efficient search strategies used by the high hypnotizables, their performance improved and was not significantly different from that of the high hypnnotizable Ss. Implications of these results for teaching search strategies are discussed.
Wallace, Benjamin (1990). Imagery vividness, hypnotic susceptibility, and the perception of fragmented stimuli. Journal of Personality and Social Psychology, 58, 354-359.
Two experiments were conducted to determine the role of hypnotic susceptibility level (high or low) and imaging ability (vivid or poor) in the performance of gestalt closure tasks. In Experiment 1, subjects were required to identify fragmented stimuli in the Closure Speed Test and in the Street Test. In Experiment 2, subjects reported on fragmented stimuli that were projected to the right eye and subsequently produced an afterimage. Individuals were asked to identify the composite if possible and to report on the duration of the afterimage. In both experiments, hypnotic susceptibility level and imaging ability affected reports of gestalt closure. The greatest number of correct closures was reported by those who were both high in hypnotic susceptibility and vivid in imaging ability. In addition, in the second experiment, this group also reported the longest enduring afterimage. These results are discussed in terms of the processes required to perform in a gestalt closure task.
1989
Miller, Scott D. (1989). Optical differences in cases of multiple personality disorder. Journal of Nervous and Mental Disease, 177 (8), 480-486.
Nine patients (aged 24-43 years) diagnosed with multiple personality disorder (MPD) and 9 control Ss role-playing MPD were given complete ophthalmological examinations to test whether the MPD Ss would show greater variability in visual functioning across alter personalities than would control Ss role-playing MPD. An analysis of variability of 8 optical measures in 4 prominent areas of vision was performed by comparing 2 covariance matrices for equality. Analyses showed that MPD Ss had significantly more variability across alter personalities than did their control counterparts on measures of visual acuity with correction, visual acuity without correction, visual fields, manifest refraction and eye-muscle balance. Ratings for clinical significance showed that the MPD Ss had 4.5 times the average number of changes in optical functioning between alter personalities of the control Ss.
1988
Sheehan, Peter W.; Donovan, Paul; MacLeod, Colin M. (1988). Strategy manipulation and the Stroop effect in hypnosis. Journal of Abnormal Psychology, 97, 455-460.
When asked to name the ink color of an incompatible color word (e.g., the word red printed in green ink), people show strong interference from the word. This study examined Stroop interference in subjects who were either high or low in susceptibility to hypnosis . Compared with performance in the waking state, the Stroop effect actually increased under hypnosis, a result particularly evident in the high- susceptible subjects. This contradicts the notion that high susceptibility subjects freely select appropriate strategies when hypnotized, a conclusion strengthened by an analysis of reported strategies in the two states. However, when provided with an attentional focusing instruction under hypnosis, high susceptibility subjects sharply reduced the Stroop effect, whereas low-susceptible subjects decreased it only slightly. One role of hypnosis may be to assist the subject in tuning attention, but only when an appropriate strategy is provided.
Wallace, Benjamin (1988). Hypnotic susceptibility, visual distraction, and reports of Necker cube apparent reversals. Journal of General Psychology, 115, 389-396.
Subjects, either susceptible (n = 50) or resistant (n = 50) to hypnotic suggestion, were asked to report on frequency of apparent reversals (ARs) to the Necker cube illusion. Such reports were made in the presence or absence of various types of visual, geometric surrounds (squares, triangles, crosses, or parallelograms). In agreement with a number of previous experiments, susceptible subjects reported perceiving more ARs than did resistant subjects. This difference held whether visual surrounds were present or absent. The presence of surrounds did serve to reduce AR reports regardless of hypnotic susceptibility level. The results are examined in terms of the ability of subjects to selectively attend when confronted with potential visual distractors.
1987
Friedman, Howard; Taub, Harvey A.; Sturr, Joseph F.; Monty, Richard A. (1987). Visual information processing speed in hypnotized and nonhypnotized subjects. Journal of General Psychology, 114 (4), 363-372.
Using a backward-masking paradigm with a bias-free and ceiling-free psychophysical task, we tested hypnotized and control subjects for speed of visual information processing. Approximately half of each group received visual imagery suggestions in an attempt to influence attention. Imagery produced no significant differential effect. Although an absence of a hypnotizability-performance relationship was in keeping with findings of a previous study, those subjects in the present study who performed under hypnosis were, as a group, significantly superior to the other subjects in speed of information processing.
1986
Friedman, Howard; Taub, Harvey A.; Sturr, Joseph F.; Church, Katherine L.; Monty, Richard A. (1986). Hypnotizability and speed of visual information processing. International Journal of Clinical and Experimental Hypnosis, 34, 234-241.
Following the determination of the luminance threshold of each S, high and low hypnotizable Ss were tested for speed of information processing using a backward masking paradigm with a bias-free and ceiling-free psychophysical task. No significant relationship between hypnotizability as measured by the Stanford Hypnotic Susceptibility Scale, Form A (SHSS:A) of Weitzenhoffer and Hilgard (1959) and speed of information processing was observed. The order of administering SHSS:A, pre- or postthreshold task, was significantly related to luminance threshold. Results were compared to other studies wherein some evidence for a relationship between hypnotizability and speed of visual information processing had been offered.
NOTES
106 college students were tested using tachistoscopic presentation of stimuli. 52 Ss received the SHSS:A immediately prior to the experimental tasks, 54 immediately after, and testing was terminated for each Subject after they failed 3 successive items. The test flash was set at 0.3 log units above threshold, i.e. double the threshold intensity. A trial consisted of 2 observation intervals, separated by warning tones. The test flash occurred randomly in one of the two intervals. The S indicated which observation interval contained the test flash by pressing a button. Feedback tones gave S information about the correct response.
“The masking experiment was begun with the suprathreshold test flash occurring 250 milliseconds prior to the onset of the larger bright masking stimulus. As before, a two-interval forced -choice staircase procedure was used, but this time the test intensity was constant, and ISI was changed. If S ‘hit’ three trials in a row, ISI was decreased by 10 milliseconds. The ISIs continued to decrease in 10-millisec steps, until S “missed,” causing an increase in ISI” (p. 348).
RESULTS were analyzed by 2 x 2 x 2 ANOVA (Hypnotizability, sex, and order of hypnotizability measurement). High hypnotizables = 7-12 on the SHSS:A, and low hypnotizables = 0-6. Ss receiving SHSS:A prior to the tasks had a significantly lower luminance threshold (-1.99 log mL) than did those having it after tasks (-1.93 log mL), p<.05. None of the other analyses were significant. No significant relationships were observed vis a vis the masking task, and the mean masking thresholds were almost identical for the lows and highs.
DISCUSSION. "Spanos (1982), in studying the effects of hypnotizability and suggestions in altering auditory sensitivity, reviewed the difficulties inherent in the measurement of perceptual accuracy and emphasized the role of response bias in the confounding of results" (p. 239). Secondly, these tasks reflect more fundamental, central processes and use more neutral stimuli than letter recognition used earlier. "Thus, while the masking effects of both the previous recognition tasks (masking by pattern) and the current detection tasks (masking by nearby contours) are presumably mediated through similar high level central processes, the differences in findings could possibly have been related to additional processing cues required in letter recognition" (p. 239). A footnote mentions, "Other studies have shown that with stimulus configurations similar to that used in the present study, there are significant central masking effects (Battersby & Wagman, 1962; Markoff & Sturr, 1971; Turvey, 1973)" (p. 239).
"Quite intriguing is the luminance threshold finding which, although not as robust as one would desire, suggests that a hypnotic induction procedure given prior to a task may significantly affect sensitivity on that task. Speculatively, the relaxation suggestions inherent in SHSS:A may account for the changes in luminance threshold" (p. 239).
Wallace, Benjamin (1986). Latency and frequency reports to the Necker cube illusion: Effects of hypnotic susceptibility and mental arithmetic. Journal of General Psychology, 113 (2), 187-194.
An experiment (N = 32) was conducted to assess latency of first apparent reversal (AR) and AR frequency while observing the Necker cube illusion. Subjects who were either high in hypnotic susceptibility (susceptibles) or low in hypnotic susceptibility (resistant subjects) observed the cube either while performing or not performing mental addition problems. Susceptibles reported perceiving the first AR more quickly and a greater frequency of ARs than did resistant subjects. Also, latency of the first AR was negatively correlated with AR frequency. These results were interpreted in terms of the ability of susceptibles to allocate concentrative or selective attention in a manner that was conducive to faster performance when faced with competing tasks.
1985
Nogrady, Heather; McConkey, Kevin M.; Perry, Campbell (1985). Enhancing visual memory: Trying hypnosis, trying imagination, and trying again. Journal of Abnormal Psychology, 94 (2), 195-204.
Tested visual recall memory of high (n = 24) and low (n = 24) hypnotizable undergraduates (screened under the Harvard Group Scale of Hypnotic Susceptibility and the Stanford Hypnotic Susceptibility Scale) for black and white line drawings of common objects in either hypnosis, imagination, or control conditions. Memory performance in terms of both correct and incorrect items increased appreciably across the recall tests. Neither hypnosis nor imagination enhanced recall beyond that of normal repeated testing. Hypnotizability was not related to the amount of correct material recalled but was related to the amount of incorrect material reported. High hypnotizable Ss in the hypnosis condition were more likely than other Ss to confidently rate the incorrect material as correct. Findings are discussed in terms of the impact of hypnosis on and the relevance of hypnotizability to enhancing visual memory.
1984
Magnavito, F.; Gaupp, L. (1984, October). Absorption, hypnotic susceptibility, and automatization of visual attention. [Paper] Presented at the annual meeting of the Society for Clinical and Experimental Hypnosis, San Antonio, TX.
NOTES
Absorption (Tellegen Scale) correlated .62 with SHCS and -.45 with a measure of visual automatization. They conclude that highly absorption-prone individuals attend more to sensory information, processing their environment in a childlike, less automatized manner. The measure of visual automatization, H, was obtained by camera recorded eye movements and fixations as Ss viewed slides in any way they desired.
Venn, J. (1984). The spiral technique of hypnotic induction: A brief communication. International Journal of Clinical and Experimental Hypnosis, 32 (3), 287-289.
The spiral method directs the patient's attention to a sequence of body locations. During 3 years of clinical trials, the method proved valuable in hetero-hypnotic induction and in training patients in self-relaxation. The spiral technique is compared with progressive relaxation, and advantages of this method are discussed. A brief case report is presented.
NOTES
The induction is based on a technique published in W. B. Joy (1979), Joy's Way. Los Angeles: Tarcher. It guides patient in a (spiral) focused awareness of locations in and around the body, e.g. heart, solar plexus, middle chest, lower abdomen, throat, left shoulder, left hip, base of spine, right hip, right shoulder, center of forehead, left elbow, left knee, right knee, right elbow, center of scalp, left hand, left foot, right foot, right hand, and point in midair several inces above the center of the scalp.
1983
Crawford, Helen J.; Allen, Steven N. (1983). Enhanced visual memory during hypnosis as mediated by hypnotic responsiveness and cognitive strategies. Journal of Experimental Psychology: General, 112 (4), 662-685
To investigate the hypothesis that hypnosis has an enhancing effect on imagery processing, as mediated by hypnotic responsiveness and cognitive strategies, four experiments compared performance of low and high, or low, medium, and high hypnotically responsive subjects in waking and hypnosis conditions on a successive visual memory discrimination task that required detecting differences between successively presented picture pairs in which one member of the pair was slightly altered. Consistently, hypnotically responsive individuals showed enhanced mean number of correct performance during hypnosis, whereas nonresponsive ones did not. Hypnotic responsiveness correlated .52 (p < .001) with enhanced performance during hypnosis, but it was uncorrelated with waking performance (Experiment 3). Reaction time was not affected by hypnosis, although high hypnotizables were faster than lows in their responses (Experiments 1 and 2).
NOTES
Subjects reported enhanced imagery vividness on the self-report Vividness of Visual Imagery Questionnaire during hypnosis. The differential effect between lows and highs was in the anticipated direction but not significant (Experiments 1 and 2).
Two cognitive strategies appeared to mediate visual memory performance: (a) detail strategy (memorization and rehearsal of individual details) and (b) holistic strategy (looking at and remembering the whole picture with accompanying imagery). Both lows and highs reported predominantly detail-oriented strategies during waking; however the highs shifted to a more holistic strategy during hypnosis. It appears that high hypnotizables have a greater capacity than lows for cognitive flexibility (Battig, 1979).
Results are discussed in terms of Paivio's (1971) dual coding theory and Craik and Tulving's (1975) depth of processing theory. The authors also discuss whether hypnosis involves a shift in cerebral dominance, as reflected by the cognitive strategy changes and enhanced imagery processing.
Nash, John (1983). Negative visual hallucination and concomitant changes in cortical event-related potentials (Dissertation, University of California, Santa Barbara). Dissertation Abstracts International, 45 (2), 716-B. (Order No. DA 8411224)
"The purpose of this investigation was to examine the effects of negative visual hallucination (NVH) on cortical event-related potentials (ERPs), and to compare these effects with those of selectively attending to and ignoring stimuli. Five highly hypnotically susceptible subjects, four female and one male, were trained to block from subjective experience, i.e., negatively hallucinate, a ring of strobe-illuminated circles surrounding a central, independently strobe-illuminated circle. This stimulus array was modeled after part of the Titchener-Ebbinghaus circle illusion, since previous research had shown that subjects could attenuate the effects of the optical illusion via NVH of the outer, illusion-producing circles. "Analysis of the ERP data revealed amplitude and latency changes in various ERP components across the three experimental conditions (Attend, Ignore, NVH) for the four female subjects, a negative result which is explained in motivational terms. "The most noteworthy finding was the selection of the P3 amplitude variable at C2 by stepwise discriminant analysis for the four females, and the fact that this amplitude systematically decreased across conditions from largest in Attend to smallest in NVH. A variety of individual patterns were observed in terms of other ERP components which allowed discrimination (successful classification) among the three conditions. The results suggest that both Ignoring and NVH of a stimulus result in a decrease in the subjective certainty of perception of the stimulus. Individual differences in patterns of ERP changes are interpreted in terms of differing strategies for execution of the experimental instructions. The results support the view that NVH instructions produce distinctive ERP effects and that NVH generally can be viewed as an extreme level of ignoring" (p. 716).
Spanos, Nicholas P.; Dubreuil, Debora L., Saad, Carol L., Gorassini, Donald (1983). Hypnotic elimination of prism-induced aftereffects: Perceptual effect or responses to experimental demands?. Journal of Abnormal Psychology, 92 (2), 216-222.
Two experiments assessed adaptation to displacing prisms in hypnotically limb-anesthetized Ss. Experiment I with 18 college students disconfirmed the hypothesis that the displacement aftereffect is eliminated in limb-anesthetized hypnotic Ss who adapt to prisms in the absence of a visual target. Such Ss showed as large a displacement aftereffect as control Ss who received neither a hypnotic induction procedure nor an anesthesia suggestion. Experiment II with 30 undergraduates demonstrated that under some testing conditions hypnotic Ss complied with experimental demands and eliminated the behavioral but not the perceptual component of the aftereffect.
Wagstaff, Graham F. (1983). Suggested improvement of visual acuity: A statistical reevaluation. International Journal of Clinical and Experimental Hypnosis, 31 (4), 239-240.
This is a re-analysis of data presented by Sheehan, E.P., Smith, H.V., & Forrest, D.W. (1982), A signal detection study of the effects of suggested improvement on the monocular visual acuity of myopes. International Journal of Clinical and Experimental Hypnosis, 40, 138-146. "In sum, a more appropriate conclusion to be drawn from Sheehan et al.'s (1982) results is that suggestions for improving visual acuity have little effect, but listening to music actually appears to reduce sensitivity. This reinterpretation of Sheehan et al.'s (1982) result is purely a comment on their conclusions, not their methodology.
1982
Cunningham, Paul V.; Blum, Gerald S. (1982). Further evidence that hypnotically induced color blindness does not mimic congenital defects. Journal of Abnormal Psychology, 91, 139-143.
Six undergraduate women, highly skilled in hypnotic techniques, were trained under hypnosis with a color mixer to experience red, green, blue, and total color blindness and were then programmed for the same responses in the posthypnotic state under conditions of amnesia. After awakening they were shown pseudoisochromatic plates as a preliminary check on the efficacy of the prior hypnotic instructions. The experiment consisted of successive administrations of the Farnsworth-Munsell 100-hue test, initially under normal baseline viewing conditions followed by each of the color-blind conditions in turn. Results indicate that although the observers subjectively experienced the varieties of color blindness as instructed, their responses differed from specimen responses of individuals with congenital defects in color discrimination. Implications for interpreting hypnotic alterations of perception are discussed.
Saccuzzo, Dennis P.; Safran, Deborah; Anderson, Virginia; McNeill, Brian (1982). Visual information processing in high and low susceptible subjects. International Journal of Clinical and Experimental Hypnosis, 30, 32-44.
High and low hypnotically susceptible Ss were compared in their ability to identify a briefly exposed informational target stimulus consisting of a letter when it was preceded (forward masking) or followed by (backward masking) a noninformational mask stimulus. There were 4 intervals between the target and mask and a no mask control for both forward and backward masking. The experiment was replicated in 2 independent sessions. In Session 1 high susceptible Ss were superior to lows in identifying the target stimulus. The superiority was not maintained in Session 2. Implications of the findings and directions for future research are discussed.
Sheehan, Eugene P.; Smith, Howard V.; Forrest, Derek W. (1982). A signal detection study of the effects of suggested improvement on the monocular visual acuity of myopes. International Journal of Clinical and Experimental Hypnosis, 30, 138-146.
2 groups of 8 Ss each, matched for suggestibility and degree of myopia, were assessed by a signal detection method in their ability to make a monocular spatial discrimination, both before and after 15 minutes of listening either to music or to taped suggestions that vision would improve. There was a significantly greater improvement in sensitivity on the part of the group of Ss listening to suggestions, and within this group, but not within the group of Ss listening to music, there was a significant negative correlation (r = -.67) between S's initial sensitivity and the amount by which it increased. There was no significant difference between the amounts by which the criterion changed in the 2 groups. In contrast with the results reported by Graham and Leibowitz (1972), there was no evidence in the present study to indicate that the amount of improvement shown by Ss depended upon either their suggestibility as measured by BSS or their refractive error.
NOTES
In contrast with the results reported by Graham and Leibowitz (1972), there was no evidence in the present study to indicate that the amount of improvement shown by Ss depended upon either their suggestibility as measured by BSS or their refractive error (p. 144).
Wallace, Benjamin; Fisher, Leslie E. (1982). Hypnotically induced limb anesthesia and adaptation to displacing prisms: Replication requires adherence to critical procedures. Journal of Abnormal Psychology, 91 (5), 390-391.
N. P. Spanos et al. (see PA, vol 66:7289) reported a failure to confirm the results of an experiment on prism adaptation reported by the present authors (see PA, vol 65:6956) that required Ss to adapt to a prismatically displaced environment when their adapting limb was hypnotically anesthetized. The present authors argue that the failure of Spanos et al to replicate their findings is due to their failure to duplicate the critical conditions of the experiment. (7 ref)
1981
Blum, Gerald S.; Nash, John; Jansen, Robert D.; Barbour, John S. (1981, June). Posthypnotic attenuation of a visual illusion as reflected in perceptual reports and cortical event-related potentials. Academic Psychology Bulletin, 3, 251-271.
Highly selected and trained hypnotic subjects, capable of ablating portions of visual stimuli from conscious awareness, showed varying degrees of ability to attenuate the Titchener-Ebbinghaus circles illusion post-hypnotically under a negative visual hallucination instruction. The presence or absence of such inhibitory skill, inferred from perceptual reports, was differentially reflected in changes in cortical event-related potentials not typically associated with shifts in selective attention. These findings point to the cognitive operation of a distinctive mechanism of selective inattention.
NOTES
Blum et al. postulate an inhibitory mechanism of the central nervous system with stages of amplification and attenuation. They suggest that individual differences in inhibitory skill may be improved with practice even for very skilled Subjects. They studied this type of inhibition using a visual illusion (the Titchener-Ebbinghaus circles) because the neural locus of such illusions is thought to be more central in the nervous system rather than at the level of the retina.
Experiment 1. Three Ss trained in using hypnosis viewed stimuli in waking and posthypnotic negative visual hallucination (NVH) conditions. All three had previously passed a negative hallucination item (not seeing a playing card of three such cards placed on a table). Training included practice sessions applying NVH to the experimental stimuli. S1 reported immediate success; S2 experienced some initial difficulty ("I have a feeling something's there") but then reported success; S3 required a couple of long practice sessions.
The classic Titchener-Ebbinghaus illusion stimuli were used. Stimuli were ten slides with drawings of a standard 17-mm-diameter black circle on the left and a comparison black circle on the right. The black circle on the right was either 14, 15, 16, 17, or 18 mm in diameter, skewed intentionally around 17, to compensate for the proportion of smaller and larger judgments applied to the comparison figure in relation to the standard. One black comparison figure was surrounded by seven 15-mm diameter white circles; the other by seven 10 mm diameter white circles. The key drawings were both black circles of 17 mm. The second set of five drawings, used as a control, contained the same black circles but lacked outer rings of white circles.
The Subject was to state whether the black circle on the right appeared larger, smaller, or the same as the standard black circle on the left. Slides were shown for 4 seconds each, with 6 seconds in between slides.
Alternating blocks of trials were given under baseline (B) condition and a posthypnotically programmed negative hallucination condition (NVH). In the NVH condition, "the rings of white circles surrounding the standard and comparison black inner circles were 'ablated' from consciousness. The observers were amnesic in the waking state for their prior hypnotic instructions and were cued in advance of a block of trials simply by the phrases 'This will be a mixed series' (referring to B, in which the stimuli appeared as they really were, some with outer rings of white circles present and others not), or 'This will be a black only series' (referring to NVH, in which all stimuli appeared to the observer as black circles only, whether the outer rings were physically present or not)" (pp. 254- 255). Sessions were spread out over 8-12 months for each observer, interspersed with a variety of other experiments.
In one session the Experimenters used a selective attention instruction, with Ss given posthypnotic suggestions to regulate their cognitive arousal to a peak of mental alertness and concentration (+AA) and focus on the inner black circles but not to negatively hallucinate the outer white circles.
Although all three Ss showed the illusion effect, they varied in ability to attenuate the illusion when negative visual hallucination suggestions were given. "S1 showed a very greatly reduced frequency of reports in the illusory direction under the NVH condition, a less marked reduction under +AA concentration, and no reduction at all under a waking instruction to ignore the outer circles; S2 revealed a moderate but significant reduction under NVH but not under +AA; S3 gave no evidence of attenuation in either condition" (p. 258). The response times for the two more successful Ss (1 and 2) with the 17 mm stimuli under NVH conditions were not different when the outer circles were either present or absent.
Experiment 2. The next year S1 and S2 returned but S3 was no longer available as a Subject; S4 and S5 were added and trained in hypnosis skills. EEG evoked response potentials (ERPs) were recorded while Ss made size judgments as in Experiment 1. Averaged ERPs for each block of 100 stimulus presentations were obtained for the first 500 milliseconds following stimulus onset. Judges blind to the experimental conditions evaluated the ERP records.
All Subjects experienced the Titchener-Ebbinghaus illusion, but again there were individual differences in ability to attenuate the illusion: S1 was the most successful; S2 gave significantly fewer responses in the larger category under NVH than B conditions; and both S1 and S2 improved attenuation performance over the previous year. S4 fell between S1 and S2 in ability; S5 was unable to attenuate the illusion in the NVH condition.
Results. "All three observers whose perceptual reports indicated some attenuation of the visual illusion during the NVH condition also showed a consistent reduction of the P2-N2 amplitude during NVH" (p. 262) at the Occipital sites. Median amplitude reduction was 36%, 40%, and 36% for S1, S2, and S4; only 7% for S5. There were no similar reductions for the other electrode sites, though "enhancement of P2-N2 amplitudes occurred in the lateral prefrontal and frontal areas in the two most successful individuals, S1 and S4" (p. 263). There was also a lag in N2 peak latencies for the three best subjects. The Experimenters noted that the N2 peak occurred 50 msec later in the frontal and prefrontal areas than in the occipital area.
In their Discussion, the authors express the view that it is not likely that faking could have occurred, for several reasons: 1. The Subjects were trained to report honestly, and they often had reported failures to experience hypnotic phenomena suggested during training sessions. 2. The task elicited rapid responses, usually in less than 2 seconds, to 10 different slides in randomized blocks of 100 trials, which would make self monitoring of responses extremely difficult. 3. Subjects exhibited a consistency of responses over experimental sessions that were widely separated in time, making conscious or unconscious deception unlikely. 4. The finding of no difference in latency between 17 mm stimuli with and without outer rings of white circles supports an interpretation of reliable reporting. 5. Differences in ERP data between the B and NVH conditions were obtained only for those Ss who successfully attenuated the illusion.
The authors also state, "In terms of our conceptual model of the mind, inhibitory skill is attributable to the capacity for invoking inhibitory action earlier in the sequence as signals are processed through stages of amplification and attenuation en route to consciousness (Blum & Barbour, 1979). In the NVH condition of the present task, first- stage attenuation ... [Subject 1] ... occurs in time to negate the illusion as well as preventing conscious awareness of the outer white circles, second-stage attenuation takes place too late to disrupt the illusion but still in time to keep the outer circles from consciousness" (p. 265). Note that the unsuccessful Subject 5 had the highest score on the screening hypnotizability tests. The variation among very high hypnotizables casts doubt on the practice of grouping Ss who score between 9 and 12 on the SHSS. "It is perhaps not surprising that many previous hypnotic studies involving alterations in such subtle phenomena as visual illusions have yielded negative results." p. 266.
N.B. None of the Ss was able to eliminate the illusion under a strong waking instruction to ignore the outer circles while judging the inner black ones. "These different results for AA and NVH instructions pinpoint the contrast between selective attention (+AA) and selective inattention (NVH)" (p. 266).
The ERP changes seen in occipital and frontal areas were in opposite directions. Thus "the data suggest an effect which seems to parallel both investment of attention (increases in late components over frontal cortex) and withdrawal of attention (relative decreases in late components over occipital cortex). This parallel leads us to speculate that our occipital decreases may have been due to active inhibition of information-processing in the occipital regions, and that the late component enhancement over frontal areas may have been due to the mobilization of resources in these areas necessary to accomplish the tonic inhibition of visual input. ... Activity in the frontal cortex apparently 'programs' inhibition on the specific sensory nuclei of the thalamus, in a modality specific and topographical way, accomplishing gating of sensory information to primary sensory cortex" (p. 268).
Zakrzewski, Kajetan; Szelenberger, Waldemar (1981). Visual evoked potentials in hypnosis: A longitudinal approach. International Journal of Clinical and Experimental Hypnosis, 29 (1), 77-86.
Visual Evoked Potentials (VEP's) were recorded in 5 healthy 20-24 year-old-females during hypnosis, hypnosis after the suggestion of blindness, and in 3 waking conditions. VEP's were recorded in these conditions 10 times within each S on different days. Both within-Ss and between-Ss analyses showed a tendency of VEP N-250 latencies (and possibly also amplitudes) to increase in hypnosis when compared to the waking state. Overall, these changes tended to be rather small. No changes were found in the earlier VEP waveform components, and some tendencies noted in the later P-300 component were largely nonsignificant. Decrease in N-250 amplitudes after the hypnotic suggestion of blindness was significant for the whole group, but was difficult to interpret, since amplitude in this condition was not significantly different from the wake control condition N-250 amplitude.
The results are considered preliminary, and a few possibilities of confirming and/or explaining them using somewhat more stringent methodology are discussed. The within-Ss approach is recommended for future studies of evoked potentials in hypnosis.
1980
Erickson, Milton H. (1980). Hypnotic alteration of sensory, perceptual and psychophysical processes. (2 ). New York: Irvington Publishers, Inc..
NOTES
This second volume of four has five sections, with chapters as follows. I. Visual Processes
1. The hypnotic induction of hallucinatory color vision followed by pseudonegative afterimages (written with E. M. Erickson)
2. Discussion: Critical comments on Hibler's presentation of his work on negative afterimages of hypnotically induced hallucinated colors (written by E. M. Erickson)
3. The induction of color blindness by a technique of hypnotic suggestion
4. An experimental investigation of the hypnotic subject's apparent ability to become unaware of stimuli
5. The development of an acute limited obsessional hysterical state in a normal hypnotic subject
6. Observations concerning alterations in hypnosis of visual perceptions (written by E. M. Erickson)
7. Further observations on hypnotic alteration of visual perception (written by E. M. Erickson)
8. An investigation of optokinetic nystagmus
9. Acquired control of pupillary responses II. Auditory Processes
10. A study of clinical and experimental findings on hypnotic deafness: I. Clinical experimentation and findings
11. A study of clinical and experimental findings on hypnotic deafness: II. Experimental findings with a conditioned response technique
12. Chemo-anaesthesia in relation to hearing and memory
13. A field investigation by hypnosis of sound loci importance in human behavior III. Psychophysiological Processes
14. Hypnotic investigation of psychosomatic phenomena: Psychosomatic interrelationships studied by experimental hypnosis
15. Hypnotic investigation of psychosomatic phenomena: The development of aphasialike reactions from hypnotically induced amnesias (written with R. M. Brickner)
16. Hypnotic investigation of psychosomatic phenomena: A controlled experimental use of hypnotic regression in the therapy of an acquired food intolerance