Amnesia and Hypnosis

The present study explored the relative effects of 2 factors (3 levels of measured hypnotic susceptibility and 3 kinds of motivation procedures) on short-term memory for a paired associate learning task. 36 Ss were stratified, according to their HGSHS:A scores (Shor & E. Ome, 1962), into 3 groups (low, medium, and high susceptibility) of 12 Ss each. The Ss within each of the 3 groups were then evenly but randomly assigned to 3 treatment conditions, which differed in terms of the kind of motivational procedure (hypnotic, waking, or waking non motivational) in which suggestions of amnesia for a recently learned paired associate task were given. Generally, results did not directly support or were sometimes contrary to predictions derived from popular hypnosis theories, which assert that posthypnotic amnesia is a reliable behavioral criterion for the “hypnotic state”.     

The effect of “alert” hypnosis and hypnotic responsiveness onreading comprehension

3 antecedent conditions were compared for their ability to increase reading comprehension. The conditions were: (a) “alert” hypnosis followed by posthypnotic suggestion of enhanced recall, (b) task motivation instructions to Ss to imagine and concentrate as much as possible, and (c) no special instructions (control). No differences in reading comprehension were found among the conditions. Also, high and low susceptible Ss performed essentially the same. The findings indicate further study and possibly long-term hypnotic training to clarify the usefulness of hypnosis for enhancing meaningful learning.     

The Conceptual Space of Good and Poor Hypnotic Subjects: A Preliminary Exploration

A form of the Semantic Differential, containing eight concepts related to hypnosis and research, was administered to 12 deeply hypnotizable and 14 nonsusceptible Ss. The good hypnotic Ss evaluated all the concepts more favorably than did the poor hypnotic Ss, with the greatest differential between the two groups occurring on the concept hypnosis. Moreover, the susceptible Ss perceived hypnosis as closer in connotative meaning to such concepts as experiment and professor, then did the nonsusceptible Ss. All differences between the two groups of Ss were of small absolute magnitude, however. Therefore, while the results suggest a relationship between hypnotic susceptibility and attitude toward hypnosis, they appear to preclude the use of the Semantic Differential as a practical predictor of hypnotic susceptibility.     

Pseudo-orientation in time as an hypnotherapeutic procedure

This investigation was carried out to obtain comparable figures on the prevalence of spontaneous and suggested posthypnotic amnesia. 91 introductory psychology students were randomly assigned to 1 of 2 groups, and were required to serve as Ss for two consecutive days. The standard induction of the Stanford Hypnotic Susceptibility Scale, Form A was used on the first day, and that of Form B on the second. Suggestibility items were then presented and served to appraise susceptibility and to test for amnesia. For 1 group, spontaneous amnesia was tested on the first day, and suggested amnesia on the second day. This order was reversed for the second group. Using as evidence of amnesia that 4 or fewer of the 10 possible items were recalled, 6 (7%) showed spontaneous amnesia on one of the two days, while a significantly larger number, 32 (35%), showed suggested amnesia. When the groups were subdivided on the basis of susceptibility scores, it was found that there is a marked advantage for suggested amnesia over spontaneous amnesia for highly susceptible hypnotic Ss, while this difference essentially disappears for low Ss. It was further found that (a) suggested amnesia is significantly greater than spontaneous amnesia whether or not one follows the other, (b) there is a small effect of the suggested posthypnotic amnesia for all levels of susceptibility, but this becomes pronounced with susceptibility scores of 6 and above, (c) the highly susceptible hypnotic Ss show no more spontaneous posthypnotic amnesia than do other Ss. While there may be a small amount of spontaneous amnesia, this amount, if any, is small compared with suggested amnesia. It may be that those Es who find a large amount of spontaneous amnesia are giving unintentional suggestions that it is to be found.     

Reactivation of memory by hypnosis and suggestion

The effects of hypnotic susceptibility (high vs. low), hypnotic condition (hypnotized vs. waking), and the order of testing (hypnosis first vs. waking first) on S's ability to recall meaningful material (specific facts about a rare chemical) 2 weeks after it was originally learned were studied using a 3-way, repeated-measures, factorial design. 52 college students (both male and female) acted as Ss for the study. No significant main effects were found, and the only significant interaction effect indicated that the memory was enhanced when tested the second time, regardless of whether it was in the waking or the hypnotized condition. The results were compared with the findings of other studies in this area using a less complex design.     

Task structure as a limiting condition of the occurrence of the treatment effects of simulation instruction in application of the real-simulating model of hypnosis

The hypothesis tested was that lack of task structure facilitates the occurrence of the treatment effects of simulation instruction in application of the real-simulating model of hypnosis. Following appropriate instruction 10 susceptible and 10 insusceptible Ss were tested in 2 sessions by an E who wm blind to the hypnotic susceptibility of Ss. In Session I, Ss were tested on an unstructured (Rorschach) and a structured (Unusual Uses Test) task. In Session II, Ss were administered the same tests again but after hypnosis had been induced and terminated. It was predicted that after receiving instructions to simulate, insusceptible Ss, initially constricted in their response, would change their behavior in Session II in the direction of increased productivity of response, while hypnotic Ss would not, and that the change would be most apparent on the unstructured task. Data supported the hypothesis. In Session II, simulating Ss, but not hypnotic Ss, significantly increased responses on the Rorschach and not on the Uses test. Results suggested that task definition is a limiting condition of the occurrence of the treatment effects of faking instruction.     

A comparison of hypnotic and waking recall

This paper presents data from a programmatic series of studies that varied the range of conditions affecting potential increase of recall, memory distortions, and distortions of confidence during and following hypnosis. All the studies used a paradigm that exposed Ss to misleading information some time before memory was tested and applied procedures in the hypnotic setting to analyze memory performance in both recognition and free recall. Results from the program failed to demonstrate any increment in accurate memory due to hypnosis, and the accuracy of memory reports in hypnosis was at times significantly reduced. Further, hypnotic recall was distinctively distorted when false information was introduced after, rather than before hypnosis. Results were discussed in relation to the role hypnotic as opposed to contextual variables may play in explaining Ss' memory test performances, and some legal implications are drawn from the data.     

Attitude differences of volunteers and nonvolunteers and of susceptible and nonsusceptible hypnotic subjects

A form of the Semantic Differential, containing 9 concepts related to hypnosis and research, was administered to 96 hypnotically inexperienced male Ss. The Ss were later asked to volunteer for a hypnotic experiment, and the hypnotic susceptibility of all volunteers (N = 51) was then determined. Semantic Differential responses of volunteers and nonvolunteers and of highly susceptible and unhyp-notizable Ss were compared. Differences between groups, in both comparisons, were generally not statistically significant, a finding which suggests that there is no simple relationship between paper-and-pencil measures of attitudes and volunteering for hypnotic experiments or hypnotizability.     

Subject posture and hypnotic susceptibility: A comparison of standing,sitting, and lyingdown subjects

Because of the prominence of relaxation instructions and suggestions of sleep within common hypnotic induction procedures, it seemed a reasonable conjecture that, in comparison to the customary sitting posture, a lying-down posture would facilitate hypnosis and a standing posture inhibit it. A preliminary experiment, using a slightly modified, tape-recorded Stanford Hypnotic Susceptibility Scale, Form C, failed to support either hypothesis. A subsequent experiment under improved conditions with 20 Ss in each group (standing, sitting, and lying down) also showed no significant difference of mean hypnotic susceptibility scores between any 2 of the conditions.

Although Ss expressed dislike for the standing posture, the only objective disadvantage seemed to be some dizziness or nausea generated for some Ss (5 out of 39 tested in the standing condition). No clear evidence exists that this effect is to be attributed to hypnosis rather than to standing with eyes closed for an appreciable time.

The results show that hypnotic behavior may be little affected by the concomitant requirements of maintaining a standing or sitting posture, even with the use of an induction which emphasizes relaxation.     

The possibility of creativity in the active stage of hypnosis

Creative capacity was studied by means of suggestions given to Ss under the condition of active hypnosis. In deep hypnosis it was suggested to S that he was a famous person with a specific talent. In a series of experiments Ss performed under active hypnosis such tasks as drawing, playing musical instruments, and playing chess. The results illustrated that creative processes can be facilitated in Ss capable of deep hypnosis and there is a carry-over of the creative achievements from hypnosis to the waking state. Low hypnotic Ss and control groups did not show improvements in the tasks. A particularly significant increase in creativity was observed when Ss capable of deep hypnosis performed several successive creative tasks while hypnotized. The theoretical and experimental definitions of several new approaches to active hypnosis are also discussed.     

Salient findings: Summaries of key findings in the research literature

An experiment was performed to investigate the relationship of hypnosis and posthypnotic amnesia to retroactive inhibition. 4 groups of 10 Ss each learned lists of adjectives in a retroactive inhibition paradigm. 2 of the groups learned the intervening list while they were hypnotized. Ss of one of these were given instructions for posthypnotic amnesia, while Ss of the other were told to recall what they had learned under hypnosis. The savings and recall scores of both these groups for items of the original list were not different from a third group that learned all 3 lists in the waking state. All 3 groups showed substantial retroactive inhibition when compared to a control group that learned no intervening list.     

Posthypnotic Amnesia: Evaluation of Selective Recall of Successful Experiences

Following suggestions of posthypnotic amnesia, Ss who are unresponsive to hypnosis tend to recall those suggestions that they passed rather than the ones that they failed; similar trends in hypnotizable Ss have been equivocal (Hilgard & Hommel, 1961; O'Connell, 1966). Modifications on the present selective recall index were developed to take into account the differences in the total recall pools available to hypnotizable and unhypnotizable individuals (who also differ in the total number of successful experiences), for the purpose of clarifying the amount of potential bias in the scoring procedure that may be accounting for previous ambiguous results. A sample of 88 volunteers were administered the Harvard Group Scale of Hypnotic Susceptibility, Form A (Shor & E. Orne, 1962). Both high and low hypnotizable Ss recalled more passed experiences during posthypnotic amnesia than would be expected by chance when alternative scoring procedures were used. This result is in accord with findings in other contexts in the normal memory literature. Although highly hypnotizable Ss were less likely to selectively recall successful experiences than were low hypnotizable Ss using 5 different scoring procedures, the differences between high and low Ss were not significant.     

Hypnotic age regression and the Ponzo and Poggendorff illusions

Parrish, Lundy, and Leibowitz (1968, 1969) reported that the magnitudes of the Ponzo and Poggendorff illusions obtained from 10 hypnotically age-regressed Ss were consonant with illusion data obtained from young children. The present study sought to replicate this finding using additional controls. Insusceptible Ss simulating hypnosis were used to equate “demand characteristics” in the experimental and control groups. A group of medium susceptible Ss was included as a further means of assessing differences between high and low susceptible Ss, should these occur. Post-experimental inquiry procedures were used to evaluate the extent to which the results were affected by Ss' perceptions of the experimental procedure and by their preconceptions of how children should respond to illusions. 18 university students (6 high, 6 middle, 6 low), whose hypnotic rating had been ascertained using SHSS:C (Weitzenhoffer & Hilgard, 1962) and the Diagnostic Rating Procedure of Orne and O'Connell (1967) underwent the procedures used by Parrish, Lundy, and Leibowitz. The present study was unable to replicate the original findings in any of the comparison groups. It was not possible to account for the failure to replicate, though differences between the 2 studies in selection of hypnotic Ss and in the use of simulating controls were pointed to as potential factors.     

Differentiation of hypnosis and relaxation by analysis of narrow band theta and alpha frequencies

Narrow band theta and alpha activity were recorded over anterior and posterior sites before, during, and after hypnosis in high and low hypnotically susceptible subjects (N = 16). In theta, high susceptibles had greater activity posthypnosis, otherwise there were no group differences. These findings common to low and high susceptibles suggest that theta is an index of relaxation that continues after hypnosis in highs. In alpha in high susceptibles, posterior power increased from the prehypnosis to hypnosis conditions and decreased posthypnosis. Exactly the converse effects were seen in lows. Furthermore, highs had greater alpha power than lows during both prehypnosis and hypnosis conditions, demonstrating an association of alpha with hypnotic susceptibility. The results indicate that, whereas theta indexes relaxation, alpha indexes the hypnotic experience and susceptibility.     

Hypnosis,hypnotic responsiveness,and learning meaningful material

3 antecedent conditions were compared for their ability to enhance recall of meaningful material. The conditions were as follows: (a) group hypnotic instruction followed by posthypnotic suggestions of enhanced concentration and recall ability, (b) task motivation instructions to Ss to imagine and try their best, and (c) no special instructions (control). No differences in recall ability were found among the conditions. Also, high and low susceptible Ss performed essentially the same. The findings have implications for applied hypnosis and suggest that further study is indicated to clarify the usefulness of hypnosis for enhancing learning ability.     

The Role of Expectancy in Hypnotic Hypermnesia: A Brief Communication

Previous research has yielded equivocal evidence of hypnotic memory enhancement. The present experiment assessed the effects of expectancy and hypnotizability on recall for videotaped material under waking and hypnotic conditions. Ss (N = 138) were informed of hypnotic induction either before (expectancy condition) or after (no expectancy condition) watching a videotaped enactment of a crime and completing an initial waking recall test (R1). Both groups then underwent hypnotic induction, and completed the test again (R2). Ss raw recall scores were significantly greater under hypnotic than waking conditions, but this hypermnesia was not evident when scores were corrected for mere increase in rate of responding. Ss expecting later hypnosis scored significantly higher than Ss with no such expectations, but again, this difference was not evident in corrected scores. Hypnotizability of Ss was, however, related to corrected recall, with high hypnotizable Ss displaying the greatest increase in rate of responding from R1 to R2. No evidence for the hypothesized “suppression effect” underlying hypnotic hypermnesia was found.     

Hypnosis decouples cognitive control from conflict monitoring processes of the frontal lobe

Hypnosis can profoundly alter sensory awareness and cognitive processing. While the cognitive and behavioral phenomena associated with hypnosis have long been thought to relate to attentional processes, the neural mechanisms underlying susceptibility to hypnotic induction and the hypnotic condition are poorly understood. Here, we tested the proposal that highly hypnotizable individuals are particularly adept at focusing attention at baseline, but that their attentional control is compromised following hypnosis due to a decoupling between conflict monitoring and cognitive control processes of the frontal lobe. Employing event-related fMRI and EEG coherence measures, we compared conflict-related neural activity in the anterior cingulate cortex (ACC) and control-related activity in the lateral frontal cortex (LFC) during Stroop task performance between participants of low and high hypnotic susceptibility, at baseline and after hypnotic induction. The fMRI data revealed that conflict-related ACC activity interacted with hypnosis and hypnotic susceptibility, in that highly susceptible participants displayed increased conflict-related neural activity in the hypnosis condition compared to baseline, as well as with respect to subjects with low susceptibility. Cognitive-control-related LFC activity, on the other hand, did not differ between groups and conditions. These data were complemented by a decrease in functional connectivity (EEG gamma band coherence) between frontal midline and left lateral scalp sites in highly susceptible subjects after hypnosis. These results suggest that individual differences in hypnotic susceptibility are linked with the efficiency of the frontal attention system, and that the hypnotized condition is characterized by a functional dissociation of conflict monitoring and cognitive control processes.     

Psychophysiological correlates of hypnosis and hypnotic susceptibility

This article reviews and summarizes electroencephalographic (EEG)-based research on physiological and cognitive indicators of hypnotic responding and hypnotic susceptibility, with special attention to the author's programmatic research in this area. Evidence that differences in attention levels may account for hypnotic depth and individual differences in hypnotizability is provided with traditional EEG rhythms, event-related potentials, and 40-Hz EEG activity. The alteration of stimulus perception may be a secondary effect with respect to allocation of attentional resources. In both nonhypnosis and hypnosis conditions, high hypnotizables appeared to show greater task-related EEG hemispheric shifts than did low hypnotizables. Findings concerning cognitive and physiological correlates of hypnotic analgesia are discussed with respect to hemispheric functioning in the apparent control of focused and sustained attention. The conclusion is that although a definitive EEG-based signature for hypnosis and hypnotizability is not yet established, there are a number of promising leads.     

Peripheral skin temperature and vasomotor responses during hypnotic induction

The present study is a further investigation of the hypothesis proposed by Reid and Curtsinger (1968) that hypnosis involves changes in peripheral vasomotor responses and skin temperature. 20 male Ss, screened for hypnotic susceptibility, participated in 2 experimental sessions. Each S was hypnotized in 1 session and simply given instructions to relax in the other session. Peripheral skin temperature and pulse volume were continuously monitored through-out each session. The resulting data were analyzed to determine the effects of hypnosis on these physiological measures. Under both conditions, a tendency for increased skin temperature and increased vasodilation was found. It was concluded that neutral hypnosis does not involve changes in these measures which are appreciably different from the changes associated with relaxation.     

Peripheral skin temperature responses to hot and cold suggestions

10 male Ss, screened for hypnotic susceptibility, were hypnotized in 1 experimental session and given “method acting” instructions in another experimental session. Suggestions designed to increase and to decrease peripheral skin temperature, which was continuously monitored throughout each session, were administered under both conditions. The resulting data were analyzed to determine the effects of hypnosis, suggestions, and time. A significant time effect and a significant hypnotic-time interaction were found, but there was no difference due to the specific suggestions. When hypnotized, Ss tended to maintain a constant temperature throughout the suggestion period, while, when given “method acting” instructions, peripheral temperature tended to increase.