Abstract
Hypnotherapy is used in clinical settings to treat mental and physical health-related conditions. Hypnotic response can be measured through hypnotizability scales to help interventionists personalize treatment plans to suit the patients’ individualized hypnotic abilities. Examples of these scales are the Elkins Hypnotizability Scale (EHS) and the Stanford Hypnotic Susceptibility Scale, Form C (SHSS:C). According to previous literature, these scales have good discriminating ability and internal consistency (α = 0.85) in collegiate samples, but the psychometric properties of the EHS for a targeted clinical population have not been determined yet. This study assessed said properties, and results showed adequate reliability of the EHS in a targeted clinical sample and strong convergent validity of the EHS to the SHSS:C. The authors conclude that the EHS is a strong and useful measure of hypnotizability that is pleasant, safe, brief, and sensible to individualities in hypnotic ability found in diverse clinical samples.
Zusammenfassung:
Hypnotherapie wird im klinischen Bereich zur Behandlung seelisch und körperlich bedingter Leiden eingesetzt. Die hypnotische Reaktion kann mittels Hypnotisierbarkeitsskalen gemessen werden um den Therapeuten personalisierte Behandlungspläne an die Hand zu geben, angepasst an die je individuellen hypnotischen Fähigkeiten der Patienten. Beispiele für diese Messinstrumente sind die Elkins Hypnotizability Scale (EHS) und die Stanford Hypnotic Susceptibility Scale, Form C (SKSS:C). Entsprechend der Literatur verfügen diese Skalen über gutes Diskriminierungsvermögen und interne Konsistenz (α = 0.85) in Hochschulstichproben, indessen sind die psychometrischen Eigenschaften des EHS für die klinische Zielpopulation noch nicht ermittelt worden. Diese Studie ermittelt die genannten Eigenschaften und die Ergebnisse zeigten eine angemessene Reliabilität der EHS in einer anvisierten klinischen Stichprobe und eine hohe Übereinstimmung der Validität von EHS du SHSS:C. Die Autoren folgern, dass die EHS ein starkes und nützliches Messinstrument für Hypnotisierbarkeit ist und angenehm, sicher, nicht zeitaufwändig und sensibel für die jeweils individuellen Fähigkeiten in unterschiedlichen klinischen Stichproben.
Alida Iost-Peter
Dipl.-Psych.
Résumé :
L’hypnothérapie est utilisée en milieu clinique pour traiter les troubles mentaux et physiques liés à la santé. La réponse hypnotique peut être mesurée à l’aide d’échelles d’hypnotisabilité pour aider les intervenants à personnaliser les plans de traitement en fonction des capacités hypnotiques individuelles des patients. Des exemples de ces échelles sont l’échelle d’hypnotisabilité d’Elkins (EHS) et l’échelle de sensibilité hypnotique de Stanford, forme C (SHSS :C). Selon la littérature antérieure, ces échelles ont une bonne capacité discriminante et une cohérence interne (α = 0,85) dans les échantillons de population universitaire, mais les propriétés psychométriques de l’EHS pour une population clinique ciblée n’ont pas encore été déterminées. Cette étude a évalué ces propriétés et les résultats ont montré une fiabilité adéquate de l’EHS dans un échantillon clinique ciblé et une forte validité convergente de l’EHS vers le SHSS : C. Les auteurs concluent que l’EHS est une mesure solide et utile de l’hypnotisabilité qui est agréable, sûre, brève et sensible aux particularités des capacités hypnotiques trouvées dans divers échantillons cliniques.
Gérard Fitoussi, M.D.
President-elect of the European Society of Hypnosis
Resumen:
Cameron Alldredge y Gary R. Elkins
Las teorías de estado y no estado de la hipnosis han dominado el campo durante décadas y han ayudado al avance de la hipnosis clínica y científicamente. Sin embargo, se quedan cortos de varias maneras, incluida la consideración suficiente de los procesos inconscientes/experienciales. Nuestra nueva teoría se basa en la teoría del yo cognitivo-experiencial de Epstein, un modelo de proceso dual que brinda una comprensión integral del sistema racional y el sistema experiencial y destaca que, si bien interactúan de manera sinérgica, sus características y modos de operación difieren enormemente. El sistema racional, influenciado por la lógica y la razón, exige recursos cognitivos y opera esforzadamente con un afecto mínimo. Por el contrario, el sistema experiencial está impulsado emocionalmente, es asociativo y codifica la realidad en imágenes y sentimientos sin un esfuerzo consciente. Nuestra teoría, la teoría experiencial adaptativa, postula que la respuesta hipnótica compleja es atribuible a la capacidad de un individuo para adaptarse y cambiar deliberadamente del procesamiento principalmente dentro del sistema racional al sistema experiencial. Una mayor asociación con el sistema experiencial produce alteraciones en el procesamiento de la realidad, lo que permite que las sugestiones hipnóticas se internalicen y actúen sin una interferencia excesiva del sistema racional.
Vanessa Muñiz
Baylor University, Waco, Texas, USA
Hypnosis is a state of consciousness that involves focused attention and reduced awareness of external surroundings leading to increased responsiveness to suggestion (Elkins et al., 2015). Clinical hypnosis is useful to practitioners for its efficiency in alleviating symptoms and in the treatment of mental and physical health-related conditions. Some examples include, and are not limited to, diminishing depressive symptoms, PTSD, stress, and chronic pain while improving sleep quality, the immune system, and overall quality of life (Milling et al., 2019; Olendzki et al., 2020; Rotaru, 2015; Téllez et al., 2020). The ability to respond to hypnotic suggestions is measured by hypnotizability scales. Hypnotizability is the ability to “experience suggested alterations in physiology, sensations, emotions, thoughts, or behavior during hypnosis” (Elkins et al., 2015, p. 383). Scales that measure hypnotizability help identify patients’ responses to hypnotic suggestions and may assist therapists in the personalization of treatment plans that best suit patients’ individual hypnotic differences (Barabasz & Perez, 2007; Barabasz & Watkins, 2005; Elkins, 2014; Spiegel & Spiegel, 2004).
Examples of hypnotizability scales include the Stanford Hypnotic Susceptibility Scale, Form C (SHSS:C; Weitzenhoffer & Hilgard, 1962) and the Elkins Hypnotizability Scale (EHS; Elkins, 2014). These measure individual differences in hypnotizability and are built upon dissociative theories of hypnotizability (Frankel, 1990; Hilgard, 1973; Woody & Sadler, 2008). However, the EHS is designed to be more time efficient and provide a more pleasant experience than the SHSS:C. Specifically, the EHS was originally developed to be (1) pleasant and safe, (2) time efficient (i.e., take 30 minutes or less to administer), (3) include enough items that are sufficiently difficult to discriminate between low, moderate, high, and very high hypnotizable patients, and (4) have acceptable reliability and validity to be useful in clinical and research settings (Elkins, 2014).
The EHS has shown strong reliability and validity in college and general-adult populations. The EHS has demonstrated strong internal consistency within a general adult sample (α = .85) (Elkins et al., 2015) and within a collegiate sample (α = .78) (Kekecs et al., 2016). Its items show good discriminating ability, and scores of the EHS highly correlate with the SHSS:C (rs = .86) (Elkins, 2014; Kekecs et al., 2016). In addition, when compared to the SHSS:C, the EHS demonstrates higher test-retest reliability (r = .82) and a strong correlation of rs = .71-.92 (Kekecs et al., 2021).
A review of the impact of hypnotizability in clinical care settings found a medium effect size (r = 0.47) for the SHSS:C (Hilgard, 1965). However, the psychometric properties for a targeted clinical population in the EHS have not been determined yet. Validating the EHS for a clinical sample is important because it can be beneficial to clinicians to personalize future treatment plans that optimize patients’ well-being. Previous studies have shown that hypnotizability is a good moderator of response to hypnotic induction and interventions (Elkins et al., 2011; Flammer & Bongartz, 2003; McGlashan et al., 1969; Milling et al., 2006, 2007). For instance, in Flammer and Bongartz’s (2003) study, hypnotizability correlated with treatment outcomes (r = .44; p < .001) for disorders such as irritable bowel syndrome, pain, chronic headaches, warts, and smoking cessation. The objective of this study is to determine the reliability and examine the convergent validity of the EHS to the SHSS:C in a targeted clinical sample. We hypothesize that the total score of the EHS will demonstrate a recommended Cronbach’s alpha above .70, and the total score of the EHS and the SHSS:C will demonstrate a correlation that is significantly greater than .6 within the targeted clinical sample.
Method
This study was part of a large clinical trial funded by an R01 grant from the National Institute of Health (NIH). Therefore, a thorough description of the study, along with results related to its primary outcomes, is published elsewhere (see Elkins et al., 2013).
Participants
Overall, this study included 173 English-speaking, postmenopausal women with reports of experiencing hot flashes. Eligibility criteria included no menstrual period over the past 12 months or no menstrual period over the past 6 months in addition to (a) either having undergone a bilateral oophorectomy or (b) having had a medically confirmed history of follicle-stimulating hormone (FSH) levels in excess of 40 mIU/ml.
Measures
Elkins Hypnotizability Scale
The Elkins Hypnotizability Scale, or EHS, is a reliable, standardized hypnotizability scale that is brief in nature and highly pleasant (Elkins, 2022). It takes approximately 25 minutes to administer by a trained assessor and consists of six items intended to induce suggestions for relaxation and guide the participant through several hypnotic suggestions. These items include inhibitory motor responses (e.g., arm heaviness), facilitative motor responses (e.g., arm levitation), facilitative cognitive responses (e.g., imagery involvement and dissociation), facilitative perceptual responses (e.g., olfactory hallucination; visual hallucination), and inhibitory cognitive responses (i.e., posthypnotic amnesia) in this order. The trained assessor records behavioral observations and the subjective experience of the participant to produce an overall hypnotizability score. Several preliminary analyses have confirmed that the EHS has high internal consistency and a high ability to discriminate among all levels of hypnotizability (Elkins, 2022). Elkins and colleagues (2015) found a high internal consistency of α = .85 within a general adult sample. Similarly, Kekecs and colleagues (2016) also found a high internal consistency of α = .78 when assessing a collegiate sample, and scores of the EHS highly correlated with those of the SHSS:C (rs = .86) (Elkins, 2014).
Stanford Hypnotic Susceptibility Scale, Form C
The Stanford Hypnotic Susceptibility Scale, Form C, or SHSS:C, is a 12-item measure of hypnotizability that takes approximately 50 minutes to administer by a trained assessor. Similar to the EHS, the SHSS:C induces hypnosis through standardized suggestions for relaxation, and the subject is then guided through a number of items. The items range from simple (e.g., motor responses) to difficult (e.g., posthypnotic amnesia) and are administered in order of increasing difficulty. Responses are scored dichotomously item-by-item based on assessor observation and summed to produce a final score of zero to 12 (Weitzenhoffer & Hilgard, 1962). The SHSS:C has good internal consistency (α = 0.85), and its items show good discriminating ability (Hilgard, 1965).
Demographic Questionnaire
Participants were asked to answer a brief demographic questionnaire to report their gender, current age, race, relationship status, level of education, and number of hot flashes experienced each day. Age, gender, and number of hot flashes experienced were used to confirm eligibility for inclusion in the analyses. Table 1 provides an overview of the frequencies and percentages associated with race, Hispanic origin, and the highest level of education received. In addition, the average age was 55 years (SD = 6.39; range = 39–.75).
Table 1.
Demographics of Clinical Sample
| Variable | N = 173 | Percentage |
|---|---|---|
|
| ||
| Race | ||
| Native American | 5 | 2.9 |
| African American | 27 | 15.6 |
| Caucasian | 130 | 75.1 |
| Other | 11 | 6.4 |
| Hispanic Origin | ||
| Yes | 18 | 10.4 |
| No | 155 | 89.6 |
| Highest Level of Education | ||
| Did not graduate | 13 | 7.5 |
| High school | 48 | 27.7 |
| Some college | 36 | 20.8 |
| Technical college | 22 | 12.7 |
| College graduate | 36 | 20.8 |
| Postgraduate | 18 | 10.4 |
Procedure
After the clinical hypnosis intervention, participants completed a follow-up assessment at week 12, during which the participants were administered the EHS, the SHSS:C, and filled out any subsequent questionnaires. Both scales were administered by trained research therapists.
Data Analysis
Data analysis using descriptive statistics was applied according to each scale and examination. A Cronbach’s alpha test was completed to examine the reliability of the EHS. Moreover, a correlation analysis was completed between the EHS and SHSS:C total scores to examine convergent validity.
Results
Reliability of the EHS in a Targeted Clinical Population
The internal consistency of the EHS within the clinical sample is α = .797. Item-drop reliability data and item-total correlations are displayed in Table 1. The item-total correlation of all items is satisfactory (rs = .592–.811), and the item-drop reliability values indicate that reliability will not increase by dropping any of the items. These data suggest that the EHS is reliable and that there are no unnecessary items within the measure.
Convergent Validity of the EHS to the SHSS:C
The EHS demonstrated a high correlation with the SHSS:C, measured with Spearman’s correlation, (rs = .894, N = 167, p < .001) thus confirming high convergent validity between the two measures. To test whether the correlation between the EHS and SHSS:C is significantly greater than .6, the correlation (rs = .894) was transformed into z-score using Fisher’s r-to-z transformation to generate a confidence interval. The transformation resulted in a z-score of 1.44, 95% CI [1.277, 1.583]. When the z-score was transformed back into a correlation, the resulting 95% CI [.855, .915] did not contain the null hypothesis correlation rs = .6. Therefore, we can reject the null hypothesis and conclude that the correlation between the EHS and SHSS:C is significantly greater than .6.
Discussion
The objective of the current study was to determine the reliability and validity of the EHS within a targeted clinical sample. It was hypothesized that the total score of the EHS would demonstrate a recommended Cronbach’s alpha above .70. Results supported this hypothesis and provided evidence that the EHS demonstrates adequate reliability (α = .797). It was also hypothesized that the total score of the EHS and the SHSS:C would demonstrate a correlation that is significantly greater than .6. Results also supported this hypothesis and demonstrated that the EHS has high convergent validity with the SHSS:C (rs = .894) within a clinical sample. Results from the present study were consistent with the extant literature on the EHS reliability, validity, and acceptability within collegiate and general adult samples (Elkins, 2014; Kekecs et al., 2016). It is noted that the present study has several limitations. The clinical sample in this study was composed solely of postmenopausal women living in central Texas. Therefore, generalizations of findings for other clinical groups should be done with caution until further research examining the psychometric properties in additional clinical populations is completed.
Conclusions
The current results, including adequate reliability and strong convergent validity, indicate that the EHS is a strong and useful measure of hypnotizability within a targeted clinical sample of postmenopausal women experiencing hot flashes. Given these findings, the present study has made an important contribution to the literature on hypnosis by providing psychometric support for a brief, pleasant, safe, and sensitive hypnotizability measure that can be administered within diverse, clinical samples.
Moreover, prior studies have also found promising results regarding the feasibility of the EHS as a therapeutic measure. Yek and Elkins (2021) reported significant increases in relaxation and a decrease in perceived stress, psychological distress, anxiety, and depression during and after two weeks of self-hypnosis practice with the EHS. Thus, agreeing with our results that the application of the EHS will be highly beneficial to patients in clinical settings. As our findings built upon the validation of the EHS within a college and general adult sample, the results give rise to the question: should the EHS serve as the new “gold standard” measure of hypnotizability?
Table 2.
Reliability if Item Dropped and Item-Total Correlations
| Item | Alpha if item dropped | Item-total correlation (Spearman ρ) |
|---|---|---|
|
| ||
| Arm Heaviness | .765 | .670** |
| Arm Lightness | .766 | .811** |
| Mental Imagery/Dissociation | .746 | .762** |
| Olfactory Hallucination | .741 | .791** |
| Visual Hallucination | .783 | .628** |
| Posthypnotic Amnesia | .789 | .592** |
Note. Cronbach’s alpha of the scale is α = .797
p < .01
Funding
Funding for this project was supported in part by award number R01 AT009384-01A1 from the National Institutes of Health, National Center for Complementary and Integrative Health (NCCIH) to Gary Elkins, PhD (Principal Investigator), Baylor University. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health or NCCIH
Footnotes
Disclosure Statement
No potential conflicts of interest were reported by the authors.
Data Availability Statement
Due to the nature of this research, participants of this study did not agree for their data to be shared publicly, so supporting data is not available.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
Due to the nature of this research, participants of this study did not agree for their data to be shared publicly, so supporting data is not available.