Posthypnotic Amnesia Research Articles

Recognition in Posthypnotic Amnesia, Revisited

ABSTRACT Three experiments studied recognition during posthypnotic amnesia (PHA) employing confidence ratings rather than the traditional yes/no format. As the criterion for recognition was loosened, an increase in hits was accompanied by an increase in false alarms, especially to distractor items that were conceptually related to, or semantically associated with, targets. Nevertheless, hits exceeded false alarms at every level of confidence. In addition, amnesic subjects had difficulty identifying the particular list on which recognized items were presented for study or the correct order in which targets appeared on the study list. Taken together, these findings support the conclusion that successful recognition during PHA is more likely to be mediated by a priming-based feeling familiarity than conscious recollection.

Posthypnotic Amnesia in Hypnotizability Assessment: Validation of a New Scoring System for the Hypnotic Induction Profile

ABSTRACT The Hypnotic Induction Profile (HIP) is a standardized assessment of hypnotizability featuring a validated 0–10 scoring system, that does not factor in posthypnotic amnesia. Using confirmatory factor analyses (CFA), we compared the 10-point scoring system with a new 12-point system that includes the posthypnotic amnesia item in independent samples of individuals with fibromyalgia (n = 98) and healthy adults (n = 97). Additionally, we explored associations of the two scoring systems with measures of hypnotic phenomena. CFA results indicate that the 12-point scoring system is a good fit for the 1-factor model of hypnotizability. Posthypnotic amnesia loaded highly on the model in the fibromyalgia sample, and moderately on the model in healthy adults. Furthermore, the 12-point scoring system correlated significantly with measures of hypnotic phenomena. We conclude that the 12-point scoring system is psychometrically equivalent yet conceptually more comprehensive than the 10-point scoring system.

German Norms of the Harvard Group Scale of Hypnotic Susceptibility, Form A (HGSHS:A) and Proposal of a 5-Item Short-Version (HGSHS-5:G)

ABSTRACT The Harvard Group Scale of Hypnotic Susceptibility, Form A (HGSHS:A), is commonly used to test hypnotizability. There is still some controversy about what exactly hypnotizability is and whether and how it can be measured, especially by the HGSHS:A. Furthermore, a wider clinical use is limited, requiring a testing time of more than 1 hour. We analyzed the German HGSHS:A version for its factorial structure, item contribution, and item difficulty based on test data from six studies, including 1276 persons, to propose a shorter version of the HGSHS:A. We hereby present a 5-item version of the HGSHS:A (HGSHS-5:G), consisting of the challenge items, that was compared with an 11-item version (highly variable posthypnotic amnesia omitted). Age- and gender-specific norms was generated. The HGSHS-5: G showed high validity, reliability, and classification agreement. It reduces test time to 30 minutes thus facilitating wider use of hypnotizability testing.

Hypnosis and learning: Pilot study on a group of students

Background Milton Erickson was the first to introduce hypnosis as a form of therapy during the post-war period. Numerous studies have evaluated the effects of hypnosis on memory, focusing principally on post-hypnotic amnesia, post-hypnotic hypermnesia, faux memories and learning growth. The aim of the present study was to determine if hypnosis can influence visual-spatial memory by increasing its performance and learning; to do this, we chose to utilise the Corsi Test (backward and forward). Methods Three hundred second-year students enrolled in the psychology faculty at the University of Catania were informed of the research and its modalities, and an e-mail was sent to inquire if they wanted to participate in the experiment. Seventy female students took part in the research; 10 were excluded because they presented a high risk of being influenced under hypnosis. The 60 subjects in the research sample were randomly divided into two groups: the Experimental Group and Control Group. The protocol prescribed administration of the Corsi Test at Time 0 (start) followed by a resting phase of 30 min. The hypnotic state was subsequently introduced, and the Corsi Test was administered again. Results The results of the Corsi Test for the Experimental Group showed statistically significant results (p<0.0004 and p<0.0001), while the results obtained in the Control Group did not show any significance. Conclusions These results led us to believe that hypnosis has the capacity to induce a nervous plasticity that supports learning of visual-spatial memory.

The Influence of Trauma on Autobiographical Memory in the Assessment of Somatoform Disorders According to DSM IV Criteria.

Recalling an event impairs an individual's later ability to recall related knowledge. Impairment in this retrieval-induced forgetting (RIF) produces a dysfunction in autobiographical memory. This, like somatic symptoms, has been documented in trauma and sexual abuse survivors. To investigate the relationship between past trauma and somatoform disorders, and the role of memory recall dysfunction in this relationship, three sex-matched groups were constituted using DSM IV criteria: Somatoform (SD) (n. 22) other Psychiatric Disorders (PD) (n. 26) and Healthy Subjects (HS) (n. 35). Responses to Stressful Life Events Screening Questionnaire revised (SLESQ-R); Direct Forgetting paradigm (DF) for autobiographical memory; Deese-Roediger-McDermott (DRM) paradigm for false memory; Stanford Scale type A for Post-Hypnotic Amnesia (PHA); Stroop Colour Word test and a digit-span for cognitive assessment; and Somatosensory Amplification Scale (SSAS), Somatic Dissociation Questionnaire (SDQ-20), and Toronto Alexithymia Scale (TAS 20) for somatic discomfort were compared among groups. SSAS, SDQ-20 and TAS F1 were correlated with SLESQ-R scores; subjects with higher numbers of traumatic events (NSE) showed greater capacity to remember items-to-be-forgotten (DFF) and higher SDQ-20 scores. Although the SD group showed higher NSE, their autobiographical memory scores were no different to those of other DSM-IV groups. The somatic-trauma-autobiographical memory impairment relationship is identified by DSM V but not DSM IV criteria for somatoform disorder. Higher NSE appears to correlate with both the presence of somatic discomfort and impaired autobiographical memory, suggesting autonoetic consciousness dysfunction in subjects with past trauma and current somatic symptom disorders.

Color preferences in participants with high or low hypnotic susceptibility.

PurposeColor preferences vary among normal individuals and psychiatric patients, and this might be related to their different levels of hypnotic susceptibility. We hypothesized that individuals with higher hypnotic susceptibility prefer more arousing colors such as red.Patients and methodsOut of 440 participants, we selected 70 with higher (HIGH) and 66 with lower (LOW) hypnotic susceptibilities, and asked them to undergo the Stanford Hypnotic Susceptibility Scale: Form C (SHSSC) test, then to order their preferences of 11 colors.ResultsThe HIGH group preferred red more and scored higher on the total SHSSC. The preference order of black was negatively predicted by the SHSSC Taste hallucination but positively by Arm rigidity, and the preference of yellow was positively predicted by Posthypnotic amnesia and Taste hallucination in the HIGH group.ConclusionThe red preference and the SHSSC associations with black and yellow preferences in participants with high hypnotic susceptibility help to clarify the individual difference of color preference and provide research hints for behavioral studies in normal individuals and psychiatric patients.

Relationship between hypnosis and personality trait in participants with high or low hypnotic susceptibility.

BackgroundThe relationship between normal personality and hypnotic susceptibility is important for understanding mental processing and mental disorders, but it is less consistent in normal people or in patients with a psychiatric disorder. We have hypothesized that the correlation exists but varies in individuals with different levels of hypnotizability.Participants and methodsWe invited 72 individuals with high (HIGH group) and 47 individuals with low (LOW group) hypnotic susceptibilities to undertake tests of NEO-PI-R and the Stanford Hypnotic Susceptibility Scale, Form C (SHSSC).ResultsThe HIGH group scored significantly higher than the LOW group did on openness to experience and its facet openness to feelings. In the LOW group, SHSSC total was positively predicted by openness to ideas; age regression was positively predicted by openness to experience and negatively predicted by extraversion; anosmia to ammonia was negatively predicted by agreeableness; and negative visual hallucination was positively predicted by openness to experience. In the HIGH group, hallucinated voice was positively predicted by openness to experience and negatively predicted by agreeableness, and posthypnotic amnesia was positively predicted by extraversion and negatively predicted by openness to experience.ConclusionThe associations between normal personality traits and hypnotic susceptibility items were weak and different in the two groups, which imply that managing mental or somatoform disorders might be through adjusting hypnotizability and mobilizing personality functions.

Discrete response patterns in the upper range of hypnotic suggestibility: A latent profile analysis.

High hypnotic suggestibility is a heterogeneous condition and there is accumulating evidence that highly suggestible individuals may be comprised of discrete subtypes with dissimilar cognitive and phenomenological profiles. This study applied latent profile analysis to response patterns on a diverse battery of difficult hypnotic suggestions in a sample of individuals in the upper range of hypnotic suggestibility. Comparisons among models indicated that a four-class model was optimal. One class was comprised of very highly suggestible (virtuoso) participants, two classes included highly suggestible participants who were alternately more responsive to inhibitory cognitive suggestions or posthypnotic amnesia suggestions, and the fourth class consisted primarily of medium suggestible participants. These results indicate that there are discrete response profiles in high hypnotic suggestibility. They further provide a number of insights regarding the optimization of hypnotic suggestibility measurement and have implications for the instrumental use of hypnosis for the modeling of different psychological conditions.

Hypnosis and cognition.

This article summarizes the contributions of hypnosis to our understanding of cognition. These contributions have been especially salient in the study of memory, and include source amnesia and the distinction between episodic and semantic memory; the occurrence of semantic priming in implicit (unconscious) memory; and paramnesia (false memory). Posthypnotic amnesia shows that explicit and implicit memory can be dissociated even under optimal encoding conditions. The hypnotic alterations of perception may expand the scope of central executive control over “low-level” sensory and perceptual processes, and offer a new perspective on perceptual couplings. Implicit (unconscious) perception in hypnosis is not subject to the same analytic limitations encountered in masked priming. In the study of “high-level” thought processes, hypnosis has played an important role in understanding the formation of delusional beliefs, and of intuitions in problem-solving. Studies of hypnosis suggest that automatic processes can be “de-automatized,” as in the reversal of Stroop interference by suggestions for hypnotic agnosia. In social cognition, Orne’s analysis of demand characteristics laid the foundations for the cognitive revolution in social psychology, by underscoring the status of subjects—and people outside the laboratory—as active, sentient, problem-solving agents. The search for correlates of hypnotizability led to the incorporation of openness to experience as a major cognitive dimension in the structure of personality. One topic for future research is the relationship between hypnotizability in children and their development of a theory of mind. Studies of hypnosis in children may shed new light on the development of the imagination.

Posthypnotic Suggestion Alters Conscious Color Perception in an Automatic Manner

The authors studied whether a posthypnotic suggestion to see a brief, masked target as gray can change the color experience of a hypnotic virtuoso. The visibility of the target was manipulated by varying the delay between the target and the mask that followed it. The virtuoso's subjective reports indicated that her conscious color experience was altered already at short delays between the target and the subsequent mask. The virtuoso's objectively measured pattern of responding under posthypnotic suggestion could not be mimicked either by control participants nor the virtuoso herself. Due to posthypnotic amnesia, the virtuoso was unaware of suggestions given during hypnosis. Importantly, the virtuoso could not alter her color perception without a hypnotic suggestion. These results suggest that hypnosis can affect even a highly automatic process such as color perception.

Altered and asymmetric default mode network activity in a “hypnotic virtuoso”: An fMRI and EEG study

Very highly hypnotizable subjects are rare, easily induced, and able to manifest the whole spectrum of hypnotic phenomena, including post-hypnotic amnesia. The aim of this study was to detect and localize by means of quantitative functional MRI and EEG changes in cortical activity during hypnosis induction and deep "pure hypnosis" in a hypnotic "virtuoso" subject. We focused on areas forming the default mode network (DMN), since previous studies found that very highly suggestible subjects in hypnosis showed decreased activity in anterior DMN. During undisturbed hypnosis, our "virtuoso" subject showed not only detectable changes in DMN, but also peculiar activations of non-DMN areas and hemispheric asymmetries of frontal lobe connectivity. Our findings confirm that hypnosis is associated with significant modulation of connectivity and activity which involve the DMN but are not limited to it, depending on the depth of the hypnotic state, the type of mental content and emotional involvement.

Doing better by getting worse: posthypnotic amnesia improves random number generation.

Although forgetting is often regarded as a deficit that we need to control to optimize cognitive functioning, it can have beneficial effects in a number of contexts. We examined whether disrupting memory for previous numerical responses would attenuate repetition avoidance (the tendency to avoid repeating the same number) during random number generation and thereby improve the randomness of responses. Low suggestible and low dissociative and high dissociative highly suggestible individuals completed a random number generation task in a control condition, following a posthypnotic amnesia suggestion to forget previous numerical responses, and in a second control condition following the cancellation of the suggestion. High dissociative highly suggestible participants displayed a selective increase in repetitions during posthypnotic amnesia, with equivalent repetition frequency to a random system, whereas the other two groups exhibited repetition avoidance across conditions. Our results demonstrate that temporarily disrupting memory for previous numerical responses improves random number generation.

Preliminary study of relationships between hypnotic susceptibility and personality disorder functioning styles in healthy volunteers and personality disorder patients

BackgroundHypnotic susceptibility is one of the stable characteristics of individuals, but not closely related to the personality traits such as those measured by the five-factor model in the general population. Whether it is related to the personality disorder functioning styles remains unanswered.MethodsIn 77 patients with personality disorders and 154 healthy volunteers, we administered the Stanford Hypnotic Susceptibility Scale: Form C (SHSSC) and the Parker Personality Measure (PERM) tests.ResultsPatients with personality disorders showed higher passing rates on SHSSC Dream and Posthypnotic Amnesia items. No significant correlation was found in healthy volunteers. In the patients however, SHSSC Taste hallucination (β = 0.26) and Anosmia to Ammonia (β = -0.23) were significantly correlated with the PERM Borderline style; SHSSC Posthypnotic Amnesia was correlated with the PERM Schizoid style (β = 0.25) but negatively the PERM Narcissistic style (β = -0.23).ConclusionsOur results provide limited evidence that could help to understand the abnormal cognitions in personality disorders, such as their hallucination and memory distortions.

A hypnotic paradigm for studying intrusive memories

Despite the importance of intrusive memories in clinical disorders, research has been limited by a dearth of paradigms that permit experimental study of intrusions. This study describes a hypnotic paradigm for eliciting intrusive memories. Forty-nine highly hypnotisable participants nominated a distressing memory prior to being hypnotised. During hypnosis, they received the suggestion that they would remember the memory in response to a designated cue after the hypnosis session. Half of the participants also received a posthypnotic amnesia suggestion for the source of the memory. Following hypnosis, all participants completed a cognitive task and during the task received the cue to recall the memory. Results demonstrated that memories experienced after posthypnotic amnesia were experienced as more involuntary and more distressing than those that were knowingly retrieved. Participants in the posthypnotic amnesia condition also demonstrated greater interference on the cognitive task after the retrieval cue was given than those who intentionally retrieved the memory. These findings suggest that posthypnotic suggestion provides a useful paradigm to elicit intrusive memories under experimental conditions.

Behavioral Persistence in Carrying Out a Posthypnotic Suggestion Beyond the Hypnotic Context: A Consideration of the Role of Perceived Demand Characteristics

Compliance with a posthypnotic suggestion (PHS) to carry out a specific behavior in a subsequent nonhypnotic setting was investigated in high and medium hypnotizable participants. The target behavior—solicited by either a PHS given during hypnosis, a waking social request, or both—was to be performed daily for an unspecified period of time. Findings indicated that the waking request alone yielded a high level of compliance, particularly among medium hypnotizable participants. In contrast, highly hypnotizable participants who received the PHS coupled with instructions for posthypnotic amnesia exhibited considerable variation in responding, whereas high hypnotizables, who received either a waking request, or a combination of PHS and waking request, performed similarly to medium hypnotizables. Postexperimental interview data suggest that perceived demand characteristics may contribute to variation in the persistence of posthypnotic behavior outside the hypnotic context.

Déjà Vu in the Laboratory: A Behavioral and Experiential Comparison of Posthypnotic Amnesia and Posthypnotic Familiarity

This experiment aimed to create a laboratory analogue of déjà vu. During hypnosis, 1 group of high hypnotizables completed a puzzle game and then received a posthypnotic amnesia suggestion to forget the game (PHA condition). Another group of highs were not given the game but received a posthypnotic familiarity suggestion that it would feel familiar (PHF condition). After hypnosis, all participants were given the game and described their reactions to it. Whereas 83% of participants in both conditions passed their respective suggestions, more in the PHF condition felt a sense of déjà vu. An EAT inquiry revealed that they experienced sensory fascination and confusion about the source of familiarity, akin to everyday déjà vu. These findings highlight the value of using hypnosis as a laboratory analogue of déjà vu and provide a framework for investigating clinical manifestations of this phenomenon.

Mesmerizing Memories: Brain Substrates of Episodic Memory Suppression in Posthypnotic Amnesia

Two groups of participants, one susceptible to posthypnotic amnesia (PHA) and the other not, viewed a movie. A week later, they underwent hypnosis in the fMRI scanner and received a suggestion to forget the movie details after hypnosis until receiving a reversal cue. The participants were tested twice for memory for the movie and for the context in which it was shown, under the posthypnotic suggestion and after its reversal, while their brain was scanned. The PHA group showed reduced memory for movie but not for context while under suggestion. Activity in occipital, temporal, and prefrontal areas differed among the groups, and, in the PHA group, between suggestion and reversal conditions. We propose that whereas some of these regions subserve retrieval of long-term episodic memory, others are involved in inhibiting retrieval, possibly already in a preretrieval monitoring stage. Similar mechanisms may also underlie other forms of functional amnesia.

Salient Findings: Identifying the Building Blocks of Hypnotizability, and the Neural Underpinnings of Subjective Pain

Two papers of special interest to the hypnosis community have appeared in the general scientific literatures. One of these papers examines the building blocks of hypnotic response. Using expanded hypnotic protocols and sophisticated multivariate statistical analyses, the authors found evidence for 4 components of hypnotizability: direct motor, motor challenge, perceptual-cognitive, and posthypnotic amnesia. The second paper examines brain correlates of the subjective reality of physically and hypnotically induced pain by tracking regional brain activation across conditions using fMRI. During suggestion-induced pain, the extent to which subjects judged the pain to be real correlated with activity in the rostral and perigenual anterior cingulate cortex and in the medial prefrontal cortex.

Multiple Hypnotizabilities: Differentiating the Building Blocks of Hypnotic Response.

Although hypnotizability can be conceptualized as involving component subskills, standard measures do not differentiate them from a more general unitary trait, partly because the measures include limited sets of dichotomous items. To overcome this, the authors applied full-information factor analysis, a sophisticated analytic approach for dichotomous items, to a large data set from 2 hypnotizability scales. This analysis yielded 4 subscales (Direct Motor, Motor Challenge, Perceptual-Cognitive, Posthypnotic Amnesia) that point to the building blocks of hypnotic response. The authors then used the subscales as simultaneous predictors of hypnotic responses in 4 experiments to distinguish the contribution of each component from general hypnotizability. This analysis raises interesting questions about how best to conceptualize and advance measurement of the ability to experience hypnosis.

Posthypnotic Amnesia For Autobiographical Episodes: Influencing Memory Accessibility and Quality

The authors examined the impact of posthypnotic amnesia on the accessibility and quality of personal memories. High, medium, and low hypnotizable individuals recalled two autobiographical episodes and rated those memories. During hypnosis, subjects were given a posthypnotic amnesia suggestion that targeted one of the episodes. After hypnosis, they recalled and rated their memories of the episodes. The posthypnotic amnesia suggestion influenced the accessibility and quality of autobiographical memory for high and some medium, but not low, hypnotizable participants. The article discusses these findings in terms of investigating and understanding the impact of posthypnotic amnesia on autobiographical memory.