Hypnosis, the timing of its introduction, and acceptance of misleading information

Allocated independent sets of 16 Ss to a crossed 2 (level of susceptibility: high, low) x 2 (information: misleading, nonmisleading) x 2 (state instruction: hypnosis, walking) design to examine the prediction that hypnosis will facilitate memory distortion when hypnotic instruction precedes the exposure of Ss to incorrect, misleading information. E. F. Loftus's recognition procedures were used to focus on the predicted effect. Free recall was also examined for memory distortion effects. Results indicated the presence of significant memory distortion for both recognition and free-recall memories. The distortion effects accompanying hypnosis, however, were not reliably greater than those accompanying waking instruction. Results are examined in relation to the operation of multiple parameters affecting memory distortion in hypnosis. Pertinent factors include the procedures for testing the effects of distortion and the level of Ss' aptitude for hypnosis.     

Hypnotic interviewing: the best way to interview eyewitnesses?

It has been suggested that hypnosis techniques may have the potential to enhance eyewitness memory in forensic investigations. However, laboratory research shows that increases in recall with hypnosis techniques are often associated with decreases in accuracy, false confidence in incorrect information, and increased suggestibility to leading questions and misleading post-event information. These problems limit the usefulness of hypnosis as an interviewing procedure. However, in practical investigations, many factors associated with hypnosis, apart from the hypnotic induction itself, might lead to memory enhancement compared with standard police interviews. For example, hypnotic interviewers, because of their psychological, clinical, and interpersonal skills, may be better interviewers than police officers. They may use effective interviewing strategies such as those associated with the “cognitive interview”; a procedure which has the potential to enhance recall by approximately 35% without the problems of memory distortion associated with hypnosis. It is concluded, therefore, that a cognitive interview procedure should be used in preference to hypnosis. © 1998 John Wiley & Sons, Ltd.     

Hypnosis and interrogative suggestibility

An attempt was made to induce memory errors through the use of misleading questioning in hypnosis. Subjects heard a short newslike story and gave initial free recall for the story details, then 4 days later were given three free recall trials: prior to hypnosis, following hypnotic induction and suggestion for enhanced memory, and after hypnosis was terminated. During hypnosis subjects were also twice interrogated with either misleading or objective questions for the story details. Accurate memory increased over the three free recall trials for all subjects regardless of hypnotizability. In recognition testing, subjects given misleading questions during the interrogation gave fewer correct responses, had more errors-in-fact as well as forgetting, and showed an increase in yielding to interrogative suggestibility over trials than subjects given objective questions. All subjects subsequently confabulated more information on the final awake free recall trial as a result of errors introduced during hypnotic interrogation process. These results help to clarify the inherent dangers in relying on hypnosis to enhance memory.     

Immediate and persisting effects of misleading questions and hypnosis on memory reports

Immediate and persisting effects of misleading questions and hypnosis on memory reports were assessed. After listening to a story, 52 highly suggestible students and 59 low and medium suggestible students were asked misleading or neutral questions in or out of hypnosis. All participants were then asked neutral questions without hypnosis. Both hypnosis and misleading questions significantly increased memory errors, and misleading questions produced significantly more errors than did hypnosis. The 2 effects were additive, so that misleading questions in hypnosis produced the greatest number of errors. There were no significant interactions with level of hypnotic suggestibility. Implications of these findings for the per se exclusion of posthypnotic testimony are discussed.     

Influence of rapport on hypnotically induced pseudomemory.

Three studies examined the influence of rapport on pseudomemory. Study 1 tested eight groups of 22 subjects in a 2 (level of susceptibility: high, low) x 2 (state instruction: hypnosis, waking) x 2 (rapport: present, reduced) design, rapport being inhibited by the hypnotist criticizing subjects' performance. Pseudomemory was tested by a second experimenter who also criticized subjects. Study 2 varied level of susceptibility and rapport for 88 hypnotically instructed subjects where criticism was offered only by the second experimenter. Study 3 analyzed effects among 44 highly susceptible hypnotic subjects where the second experimenter refrained from criticizing subjects. Data indicated a significant association between rapport with the hypnotist and pseudomemory in cued recall, strength of pseudomemory being appreciably lowered when negative hypnotist rapport was reinforced by the person testing pseudomemory.     

Expert judgments of hypnosis from subjective state reports.

Suggestibility was assessed in 60 college students after a traditional hypnotic induction, an alert induction, progressive relaxation training, or instruction in goal-directed imagery. Responsiveness to suggestion did not differ between groups. Subjects also generated open-ended reports of their states of awareness and of their experience of 3 hypnotic suggestions. A sample of these reports from 24 moderately to highly suggestible subjects were evaluated by 18 experts in the field of hypnosis. Expert ratings of subjects' open-ended reports indicated that (a) traditional hypnotic inductions produce a state of consciousness that is indistinguishable from nonhypnotic relaxation training, (b) the subjective experience of hypnotic suggestions after imagination training is indistinguishable from that after hypnotic inductions, and (c) suggestibility is unrelated to state of consciousness as assessed by experts.     

Artifact in the hypnosis-creativity relationship

Subjects who pretested high or low in hypnotic suggestibility took a creativity test either under hypnosis or in a waking state. All subjects made a global estimate of their general degree of creativity. Greater figural-spatial creativity was exhibited in the hypnosis condition than in the waking condition by both high and low suggestibles. Creativity self-reports were not corroborated by actual creative performance.     

Validation of a TAI Short Form with an Adolescent Sample

Subjects who pretested high or low in hypnotic suggestibility took a creativity test either under hypnosis or in a waking state. All subjects made a global estimate of their general degree of creativity. Greater figural-spatial creativity was exhibited in the hypnosis condition than in the waking condition by both high and low suggestibles. Creativity self-reports were not corroborated by actual creative performance.     

Furnishing hypnotic instructions with implementation intentions enhances hypnotic responsiveness

Forming implementation intentions has been consistently shown to be a powerful self-regulatory strategy. As the self-regulation of thoughts is important for the experience of involuntariness in the hypnotic context, investigating the effectiveness of implementation intentions on the suppression of thoughts was the focus of the present study. Participants were randomly assigned to one of four conditions (hypnotic instruction plus implementation intention, hypnotic instruction, implementation intention, and control condition). Results showed that participants who received information included in the "Carleton Skill Training Program" and in addition formed implementation intentions improved their hypnotic responsiveness as compared to all of the other three groups on measures of objective responding and involuntary responding. Thus, in line with the nonstate or cognitive social-psychological view of hypnosis stating that an individual's hypnotic suggestibility is not dispositional but modifiable, our results suggest that hypnotic responsiveness can be heightened by furnishing hypnotic instructions with ad hoc implementation intentions.     

Pseudomemory effects over time in the hypnotic setting

Highly (n = 36), moderately (n = 26), and low (n = 48) susceptible subjects were administered either hypnosis or waking instruction to examine the hypothesis that pseudomemory will occur for hypnotic subjects as long as 2 weeks after suggestions are given for accepting false events. Accuracy and confidence of memory were measured for all subjects, and memory was examined for free recall, structured recall, and recognition. Results indicated persistence of pseudomemory for the 2-week period for both highly and moderately susceptible subjects. Data highlighted the multifaceted operation of skill, contextual, and state instruction factors, and an hypothesis that ambiguity of communication when suggestion is delivered plays a part in the maintenance of pseudomemory over time is offered for further testing.     

Imaginative suggestibility and hypnotizability: an empirical analysis.

Hypnotic and nonhypnotic suggestibility were investigated in 2 experiments. In Experiment 1, nonhypnotic suggestibility was suppressed when measured after hypnotic suggestibility, whereas hypnotic suggestibility was not affected by the order of assessment. Experiment 2 confirmed a small but significant effect of hypnosis on suggestibility when nonhypnotic suggestibility was measured first. Nonhypnotic suggestibility was correlated with absorption, fantasy proneness, motivation, and response expectancy, but only expectancy predicted suggestibility when the other variables were controlled. Behavioral response to hypnosis was predicted by nonhypnotic suggestibility, motivation, and expectancy in a model accounting for 53% of the variance. Experiential response to hypnotic suggestion was predicted only by nonhypnotic suggestibility. Unexpectedly, hypnosis was found to decrease suggestibility for a substantial minority of participants.     

Hypnosis,hypnotic suggestibility,memory, and involvement in films

Our research extends studies that have examined the relation between hypnotic suggestibility and experiential involvement and the role of an hypnotic induction in enhancing experiential involvement (e.g., absorption) in engaging tasks. Researchers have reported increased involvement in reading (Baum & Lynn, 1981) and music-listening (Snodgrass & Lynn, 1989) tasks during hypnosis. We predicted a similar effect for film viewing: greater experiential involvement in an emotional (The Champ) versus a non-emotional (Scenes of Toronto) film. We tested 121 participants who completed measures of absorption and trait dissociation and the Harvard Group Scale of Hypnotic Susceptibility and then viewed the two films after either an hypnotic induction or a non-hypnotic task (i.e., anagrams). Experiential involvement varied as a function of hypnotic suggestibility and film clip. Highly suggestible participants reported more state depersonalization than less suggestible participants, and depersonalization was associated with negative affect; however, we observed no significant correlation between hypnotic suggestibility and trait dissociation. Although hypnosis had no effect on memory commission or omission errors, contrary to the hypothesis that hypnosis facilitates absorption in emotionally engaging tasks, the emotional film was associated with more commission and omission errors compared with the non-emotional film.     

Involvement in everyday imaginative activities, attitudes toward hypnosis, and hypnotic suggestibility.

One hundred male and 83 female subjects were assessed on absorption (i.e., involvement in everyday imaginative activities), attitudes toward hypnosis, and hypnotic suggestibility. Significant positive correlations were obtained for both sexes between absorption and attitudes and between each of these variables and hypnotic suggestibility. Multiple regression analyses indicated that most of the predicted variance in hypnotic suggestibility scores was accounted for in both sexes by the absorption variable.     

Myths and misconceptions about hypnosis and suggestion: Separating fact and fiction

We present 21 prominent myths and misconceptions about hypnosis in order to promulgate accurate information and to highlight questions for future research. We argue that these myths and misconceptions have (a) fostered a skewed and stereotyped view of hypnosis among the lay public, (b) discouraged participant involvement in potentially helpful hypnotic interventions, and (c) impeded the exploration and application of hypnosis in scientific and practitioner communities. Myths reviewed span the view that hypnosis produces a trance or special state of consciousness and allied myths on topics related to hypnotic interventions; hypnotic responsiveness and the modification of hypnotic suggestibility; inducing hypnosis; and hypnosis and memory, awareness, and the experience of nonvolition. By demarcating myth from mystery and fact from fiction, and by highlighting what is known as well as what remains to be discovered, the science and practice of hypnosis can be advanced and grounded on a firmer empirical footing.     

Directed forgetting and posthypnotic amnesia: information processing and social contexts

In three experiments we compared posthypnotic amnesia (PHA) with directed forgetting (DF), evaluating subjects' hypnotic susceptibility, hypnotized or not. Experiment 1 suggested that the memory processes in PHA and DF were not the same. Low and high susceptibility subjects responded differently in the two contexts. Experiment 2 demonstrated a context effect for highly susceptible subjects: They showed the usual DF response outside hypnosis but not during hypnosis. Experiment 3 showed that high and low susceptibility subjects responded similarly to DF instructions outside hypnosis, eliminating the susceptibility as an important variable in the DF response. We concluded: (a) The interaction of context and susceptibility was the important determinant of unusual DF responses for high susceptibles, and (b) information processing concepts are too limited to explain PHA and perhaps DF. Theories that include interactions appear necessary for an accurate understanding of hypnotic phenomena and perhaps some phenomena usually focused on by cognitive psychology.     

Distignuishing the source of memories reported during prior waking and hypnotic recall attempts

Subjects attempted to identify the occasion on which they first reported particular responses to questions that were asked twice during an experiment on hyphosis and memory 1 week earlier. During this earlier experiment, subjects of high and low hypnotizability had been randomly allocatd to one of two recall test sequences: wake-hypnosis ro wake-wake. Recall improved from the first (R1) to the second test (R2) in a comparable manner for both test sequences, indicating a failure of hypnosis to enhance memory. It is noteworthy that, when later queried about the origins of specific recollections, the majority of subjects exhibited a bias to attribute their responses to R1, regardless of whether hypnosis was used during R2. Moreover, low hypnotizables exposed to the hypnotic procedure and, to a lesser extent, high hypnotizables who recalled both times in the waking condition displayed and exaggerated tendency to overattribute recollections to R1. These data indicate that individuals cannot distinguish between memories retrieved prior to hypnosis and those that occured during hypnosis. Implications for implementing judicial standards regarding hypnosis are discussed.     

Hypnotic suggestibility,cognitive inhibition,and dissociation

We examined two potential correlates of hypnotic suggestibility: dissociation and cognitive inhibition. Dissociation is the foundation of two of the major theories of hypnosis and other theories commonly postulate that hypnotic responding is a result of attentional abilities (including inhibition). Participants were administered the Waterloo-Stanford Group Scale of Hypnotic Susceptibility, Form C. Under the guise of an unrelated study, 180 of these participants also completed: a version of the Dissociative Experiences Scale that is normally distributed in non-clinical populations; a latent inhibition task, a spatial negative priming task, and a memory task designed to measure negative priming. The data ruled out even moderate correlations between hypnotic suggestibility and all the measures of dissociation and cognitive inhibition overall, though they also indicated gender differences. The results are a challenge for existing theories of hypnosis.     

Misled subjects may know more than their performance implies

Many studies have demonstrated that subjects exposed to misleading postevent information are likely to report the misinformation with confidence on subsequent tests of memory for the event. The purpose of the present studies was to determine whether subjects exposed to misleading postevent information come to believe they remember seeing the misinformation at the original event. A second question addressed by the present studies is whether exposure to misinformation reduces subjects' ability to remember the source of items they witnessed at the original event. In two experiments, subjects viewed a slide sequence depicting an event, were subsequently exposed to misleading information or neutral information about selected aspects of the event, and were later tested on their memory for the source of original and misleading details. The results showed that exposure to misinformation did not lead subjects to believe they remembered seeing the misinformation, nor did it reduce subjects' ability to accurately identify the source of originally seen details. The same pattern of results was obtained whether subjects were tested immediately (Experiment 1) or after a 1-day delay (Experiment 2). Collectively, the results suggest that subjects may report misinformation even if they know they do not remember seeing it.     

Methodological and practical issues regarding phenomenological subtypes of highly suggestible individuals: A response to Kumar

A hypnotic induction produces different patterns of spontaneous experiences across individuals. The magnitude and characteristics of these responses covary moderately with hypnotic suggestibility, but also differ within levels of hypnotic suggestibility. This study sought to identify discrete phenomenological profiles in response to a hypnotic induction and assess whether experiential variability among highly suggestible individuals matches the phenomenological profiles predicted by dissociative typological models of high hypnotic suggestibility. Phenomenological state scores indexed in reference to a resting epoch during hypnosis were submitted to a latent profile analysis. The profiles in the derived four-class solution differed in multiple experiential dimensions and hypnotic suggestibility. Highly suggestible individuals were distributed across two classes that exhibited response patterns suggesting an inward attention subtype and a dissociative subtype. These results provide support for dissociative typological models of high hypnotic suggestibility and indicate that highly suggestible individuals do not display a uniform response to a hypnotic induction.     

Artifact and Barber's model of hypnosis: A logical-empirical analysis

Two studies examined the relevance of artifact to Barber's model of hypnosis. Study I analyzed subjects' perceptions of instructions employed by the paradigm and demonstrated strong social pressure in the model's task motivational set not present in its standard set of hypnotic induction instructions. Study II coped with the artifact by applying the standard methodology of the model but employing a set of modified hypnotic instructions equivalent in constraint to the task motivational set. Results for 88 subjects indicated a possible behavioral consequence of the artifact variable involving an interaction between type of instruction and ease of hypnotic test item; individual differences in suggestibility also appeared to discriminate conditions with respect to the artifact in question. Collectively, results indicate that the major inference drawn from the paradigm regarding the expendability of the concept of trance should be accepted with caution.