Dissociated control as a signature of typological variability in high hypnotic suggestibility

This study tested the prediction that dissociative tendencies modulate the impact of a hypnotic induction on cognitive control in different subtypes of highly suggestible individuals. Low suggestible (LS), low dissociative highly suggestible (LDHS), and high dissociative highly suggestible (HDHS) participants completed the Stroop color-naming task in control and hypnosis conditions. The magnitude of conflict adaptation (faster response times on incongruent trials preceded by an incongruent trial than those preceded by a congruent trial) was used as a measure of cognitive control. LS and LDHS participants displayed marginally superior up-regulation of cognitive control following a hypnotic induction, whereas HDHS participants’ performance declined. These findings indicate that dissociative tendencies modulate the influence of a hypnotic induction on cognitive control in high hypnotic suggestibility and suggest that HS individuals are comprised of distinct subtypes with dissimilar cognitive profiles.     

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,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.     

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.     

Impulsivity,self-control,and hypnotic suggestibility

Hypnotic responding might be due to attenuated frontal lobe functioning after the hypnotic induction. Little is known about whether personality traits linked with frontal functioning are associated with responsiveness to hypnotic suggestions. We assessed whether hypnotic suggestibility is related to the traits of self-control and impulsivity in 154 participants who completed the Brief Self-Control Scale, the Self-Regulation Scale, the Barratt Impulsiveness Scale (BIS-11), and the Harvard Group Scale of Hypnotic Susceptibility (HGSHS:A). BIS-11 non-planning impulsivity correlated positively with HGSHS:A (Bonferroni-corrected). Furthermore, in the best model emerging from a stepwise multiple regression, both non-planning impulsivity and self-control positively predicted hypnotic suggestibility, and there was an interaction of BIS-11 motor impulsivity with gender. For men only, motor impulsivity tended to predict hypnotic suggestibility. Hypnotic suggestibility is associated with personality traits linked with frontal functioning, and hypnotic responding in men and women might differ.     

The interoception and imagination loop in hypnotic phenomena

We tested a working hypothesis that the ideomotor and motor-control suggestions measured by current hypnotizability scales depend on the activation of an interoception-imagination processing loop. In three experiments, participants were exposed to an induction phase, Items 3 (mosquito hallucination) and 8 (arm immobilization) of the Stanford Hypnotic Susceptibility Scale, Form C, and a new version of Item 8 involving the additional activation of imaginative and interoception processes. We found that this modified version of Item 8 elicited greater responsiveness to suggestion, irrespective of its position in the sequence of hypnotic items. We argue that this interoception-imagination loop hypothesis provides a useful information processing analysis for understanding several hypnotic phenomena.     

Alcohol increases hypnotic susceptibility

One approach to hypnosis suggests that for hypnotic experience to occur frontal lobe activity must be attenuated. For example, cold control theory posits that a lack of awareness of intentions is responsible for the experience of involuntariness and/or the subjective reality of hypnotic suggestions. The mid-dorso-lateral prefrontal cortex and the ACC are candidate regions for such awareness. Alcohol impairs frontal lobe executive function. This study examined whether alcohol affects hypnotisability. We administered 0.8 mg/kg of alcohol or a placebo to 32 medium susceptible participants. They were subsequently hypnotised and given hypnotic suggestions. All participants believed they had received some alcohol. Participants in the alcohol condition were more susceptible to hypnotic suggestions than participants in the placebo condition. Impaired frontal lobe activity facilitates hypnotic responding, which supports theories postulating that attenuation of executive function facilitates hypnotic response, and contradicts theories postulating that hypnotic response involves enhanced inhibitory, attentional or other executive function.     

Deployment dynamics of hypnotic anger modulation

To understand the role that attention plays in the deployment timeline of hypnotic anger modulation, we composed an Attentional Blink paradigm where the first and second targets were faces, expressing neutral or angry emotions. We then suppressed the salience of angry faces through a “hypnotic numbing” suggestion. We found that hypnotic suggestion only attenuated the emotional salience of the second target (T2). By implementing drift-diffusion decision modelling, we also found that hypnotic suggestion mainly affected decision thresholds. These findings suggest that hypnotic numbing resulted from belated changes in response strategy. Interestingly, a contrast against non-hypnotized participants revealed that the numbing suggestion had the instruction-like feature of incorporating emotional valence into the attentional task-set. Together, our results portray hypnotic anger modulation as a two-tiered process: first, hypnotic suggestion alters the attentional task-set; second, provided processing and response preparation are not interrupted, a hypnotizability-dependent response based on said altered task-set is produced through late cognitive control strategies.     

Lack of correlation between hypnotic susceptibility and various components of attention

The purpose of our study was to measure the relationship between performance on various attentional tasks and hypnotic susceptibility. Healthy volunteers (N = 116) participated in a study, where they had to perform several tasks measuring various attention components in a waking state: sustained attention, selective or focused attention, divided attention and executive attention in task switching. Hypnotic susceptibility was measured in a separate setting by the Waterloo-Stanford Groups Scale of Hypnotic Susceptibility, Form C (WSGC).We found no significant correlation between any of the attentional measures and hypnotic susceptibility. Highly hypnotizables did not prove to be superior to or worse than the other individuals in any of the tests.These results do not support the neuropsychophysiological model of hypnosis, as they show no consistent relationship between hypnotic susceptibility and waking attentional performance.     

Hypnosis and belief: A review of hypnotic delusions

Hypnosis can create temporary, but highly compelling alterations in belief. As such, it can be used to model many aspects of clinical delusions in the laboratory. This approach allows researchers to recreate features of delusions on demand and examine underlying processes with a high level of experimental control. This paper reviews studies that have used hypnosis to model delusions in this way. First, the paper reviews studies that have focused on reproducing the surface features of delusions, such as their high levels of subjective conviction and strong resistance to counter-evidence. Second, the paper reviews studies that have focused on modelling underlying processes of delusions, including anomalous experiences or cognitive deficits that underpin specific delusional beliefs. Finally, the paper evaluates this body of research as a whole. The paper discusses advantages and limitations of using hypnotic models to study delusions and suggests some directions for future research.     

The neural correlates of movement intentions: A pilot study comparing hypnotic and simulated paralysis

The distinct feeling of wanting to act and thereby causing our own actions is crucial to our self-perception as free human agents. Disturbances of the link between intention and action occur in several disorders. Little is known, however, about the neural correlates of wanting or intending to act. To investigate these for simple voluntary movements, we used a paradigm involving hypnotic paralysis and functional magnetic resonance imaging. Eight healthy women were instructed to sequentially perform left and right hand movements during a normal condition, as well as during simulated weakness, simulated paralysis and hypnotic paralysis of the right hand. Right frontopolar cortex was selectively hypoactivated for attempted right hand movement during simulated paralysis while it was active in all other conditions. Since simulated paralysis was the only condition lacking an intention to move, the activation in frontopolar cortex might be related to the intention or volition to move.     

Interpretive sets, expectancy, fantasy proneness, and dissociation as predictors of hypnotic response.

College students with no prior experience of hypnosis were assessed for fantasy proneness and dissociation. In a totally separate context, they were subsequently tested for their interpretations of hypnotic suggestions, hypnotic response expectancies, and hypnotizability. Contrary to Spanos and Gorassini's (1984) hypothesis, strategic enactment of suggested responses was rarely reported, and its endorsement was not correlated with hypnotic responsiveness. Suggestibility was significantly predicted by fantasy proneness and response expectancy, but not by dissociation. A path analysis suggested that the relation between fantasy proneness and hypnotizability was partially mediated by expectancy.     

Hypnotizability, imaginative involvement, and anxiety

Forty-five undergraduate students were investigated to determine the relationship between hypnotizability, imaginative involvement (absorption), and anxiety responses. Hypnotizability was measured independently with the Creative Imagination Scale (CIS), and imaginative involvement was measured with the Absorption Scale (ABS). The results indicated moderate significant correlations between CIS, ABS, and several of the anxiety measures. In particular self-reported physiological aspects of anxiety/activation were associated with the CIS and the ABS. Three of the subjects reported having panic attacks. These subjects also exhibited high hypnotic responsiveness, and their scores on the ABS and several of the anxiety scales were considerably elevated as compared with the group mean level.     

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.     

Local pragmatics in a Gricean framework,revisited: response to three commentaries

There are two central themes that occupy the commentaries, and hence this response. The first is the character and role of what is said, both in my account, and in pragmatic theory in general. In response, I lay out in more detail the proposal from my original paper that the starting point for Gricean reasoning should be not what is said, but the pragmatically uncommitted what is expressed. As part of this argument, I restate and provide further arguments for my claim that global and local pragmatic effects are continuous. The second central theme of the commentaries concerns the value of a Gricean account, which is not intended to model the psychological processes of interpretation. I respond to this concern in Section 5, ‘Pragmatics, psychology and processing’.     

Exemplar and prototype models revisited: response strategies,selective attention,and stimulus generalization

J. D. Smith and colleagues (J. P. Minda & J. D. Smith, 2001; J. D. Smith & J. P. Minda, 1998,2000; J. D. Smith, M. J. Murray, & J. P. Minda, 1997) presented evidence that they claimed challenged the predictions of exemplar models and that supported prototype models. In the authors' view, this evidence confounded the issue of the nature of the category representation with the type of response rule (probabilistic vs. deterministic) that was used. Also, their designs did not test whether the prototype models correctly predicted generalization performance. The present work demonstrates that an exemplar model that includes a response-scaling mechanism provides a natural account of all of Smith et al.'s experimental results. Furthermore, the exemplar model predicts classification performance better than the prototype models when novel transfer stimuli are included in the experimental designs.     

Memory and suggestibility in maltreated children: age,stress arousal,dissociation, and psychopathology

The present study was designed to assess children's memory and suggestibility in the context of ongoing child maltreatment investigations. One hundred eighty-nine 3-17-year-olds involved in evaluations of alleged maltreatment were interviewed with specific and misleading questions about an anogenital examination and clinical assessment. For the anogenital examination, children's stress arousal was indexed both behaviorally and physiologically. For all children, individual-difference data were gathered on intellectual and short-term memory abilities, general psychopathology, and dissociative tendencies. Interviewers' ratings were available for a subset of children concerning the amount of detail provided in abuse disclosures. Results indicated that general psychopathology, short-term memory, and intellectual ability predicted facets of children's memory performance. Older compared to younger children evinced fewer memory errors and greater suggestibility resistance. Age was also significantly related to the amount of detail in children's abuse disclosures. Neither dissociation nor stress arousal significantly predicted children's memory. Implications for understanding maltreated children's eyewitness memory are discussed.