Intelligence and hypnotizability: is there a connection?

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Intelligence and Hypnotizability: Is There a Connection? a

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a

Emilia Geiger , Burkhard Peter , Tanja Prade & a

Christoph Piesbergen a

Ludwig-Maximilians-University, Munich, Germany

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MEG-Stiftung, Munich, Germany Published online: 16 May 2014.

To cite this article: Emilia Geiger, Burkhard Peter, Tanja Prade & Christoph Piesbergen (2014) Intelligence and Hypnotizability: Is There a Connection?, International Journal of Clinical and Experimental Hypnosis, 62:3, 310-329, DOI: 10.1080/00207144.2014.901083 To link to this article: http://dx.doi.org/10.1080/00207144.2014.901083

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Intl. Journal of Clinical and Experimental Hypnosis, 62(3): 310–329, 2014 Copyright © International Journal of Clinical and Experimental Hypnosis ISSN: 0020-7144 print / 1744-5183 online DOI: 10.1080/00207144.2014.901083

INTELLIGENCE AND HYPNOTIZABILITY: Is There a Connection? Emilia Geiger


Ludwig-Maximilians-University, Munich, Germany

Burkhard Peter Ludwig-Maximilians-University and MEG-Stiftung, Munich, Germany

Tanja Prade and Christoph Piesbergen Ludwig-Maximilians-University, Munich, Germany

Abstract: Ninety-two high school and 8 secondary school students, aged between 15 and 19 years, were tested for intelligence and for hypnotic susceptibility. No correlations could be observed for the overall sample unselected by sex because the negative correlations for male participants canceled out the positive correlations for the female subsample. These are significant for the total value of intelligence (r = .288) and highly significant for the subcategory verbal intelligence (r = .348), yet nonsignificant for the subcategories numerical intelligence and figural intelligence. Females seem to be more able to imaginatively process semantic contents induced verbally. They also seem to have a higher task motivation than males—at least during adolescence.

In the field of psychology, intelligence is one of the best researched constructs. Over the past few decades, it was also repeatedly examined in connection with other constructs. However, there are no recent studies regarding the relation between intelligence and hypnotic suggestibility that we are aware of. Older studies can by all means be found: Hull (1933, p. 86f) lists eight studies, two including schoolchildren and six including college students, conducted between 1921 and 1931. They suggest an overall positive relation between hypnotizability and intelligence; correlation coefficients are, however, rather unconvincing (four times .00 and .01, respectively; .15, .17, .33, and .34 each represented once). Twenty years later, Weitzenhoffer (1953, p. 78ff) discusses rather extensively the topic of hypnotizability and intelligence. He mentions Manuscript submitted April 19, 2013; final revision accepted April 28, 2013. Address correspondence to Burkhard Peter, MEG-Stiftung, Konradstr. 80801 Munich, Germany. E-mail: [email protected] 310

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the same studies listed by Hull (e.g., Barry, Mackinnon, & Murray, 1931) as well as some new ones that also hint toward a positive relation (e.g., Roach, 1947). In the meantime, however, results were reported suggesting a negative (e.g., Friedlander & Sarbin, 1938; Reymert & Kohn, 1940; Roach, 1941) or curvilinear relation (Curtis, 1943; Eysenck, 1943). Yet, the latter was already abrogated by Eysenck (1947) as an artifact, thus Weitzenhoffer (1953, p. 78) concludes: “The trend seems to be in the direction of a small positive correlation of the two, at least insofar as Binet-type tests are concerned.” A sex-specific relationship was not mentioned. Six years before Weitzenhoffer’s (1953) article was published, Eysenck (1947) assumed that the relationship could be discounted since it was very weak and negative for men and slightly positive for women. In a review article that was published 10 years after Weitzenhoffer’s (1953), Deckert and West (1963, p. 218) noted briefly and cautiously that “hypnotizability, in general, may correlate with intelligence [emphasis added].” Martin and Marcuse (1957) provided another paper in which intelligence is marginally associated with hypnosis. These authors wanted to disprove certain prejudices and found that students who take part in hypnosis experiments are no less intelligent than those who do not wish to participate. In addition, participating students were significantly less anxious and not at all submissive or introverted. In the 1960s, more studies with children were conducted, which were listed frequently in relevant textbooks later on (e.g., Olness & Gardner, 1988; Olness & Kohen, 1996). London (1965), for instance, found a modest positive correlation (r = .25) with 42 upper middle-class children aged 8 to 12, and a stronger one (r =.43) for 54 children aged 6 to 12 (on the vocabulary subtest of the Wechsler Intelligence Scale for Children [WISC; Wechsler, 1949]). London concluded that the lower correlation was probably the more accurate one. Jacobs and Jacobs (1966) too reported a good relationship: Those of their 64 children age 4 to 17 with the highest IQ scores were most able to achieve a trance state more often in contrast to those children with lower IQs. Because of severe neurological and/or emotional disorders, their sample, however, can hardly be compared to other samples. Although Gudjonsson (1983) still reports a negative correlation between suggestibility and intelligence, results cannot be compared with those previously mentioned. This is because Gudjonsson developed a special suggestibility test for use in police interrogations. Overall, it can be concluded that, since the end of the 1960s or the beginning of the 1970s, the possible relation between hypnotizability and intelligence was either of no interest to researchers or altogether negated. Hilgard (1965), for example, in a very short sentence on p. 206 in his then-influential book Hypnotic Susceptibility discloses, “our inability to find a correlation between intelligence and hypnosis within our samples,” and


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EMILIA GEIGER ET AL.

Kroger (1977, p. 8) frankly states that “hypnotizability is not related to intelligence.” Burrows and Dennerstein (1980, p. 210) dedicate only four and a half lines to the topic. Afterward, the term intelligence disappears completely from relevant hypnosis textbooks or only older research is reported. At the end of this article, we discuss possible reasons for this development. After almost half a century of research at a standstill, we revisited the topic of hypnotizability and intelligence as part of a more general experiment, which examined the relation between hypnotizability and personality variables. Thus, this article aims to address the question of whether a relation does exist, perhaps only for different aspects of intelligence. Since hypnotic inductions and suggestions are usually delivered verbally, the obvious assumption is a stronger relationship between hypnotizability and verbal intelligence in contrast to other forms of intelligence, like numerical or figural intelligence. Various meta-analyses regarding sex-specific differences in intelligence suggest that on average males show better results in mathematical exams whereas females perform better in verbal ones (Hyde, 1981). Based on repeatedly confirmed differences in aptitudes (Funke & Vaterrodt, 2009), sex differences will also be examined in this study.

Method Sample The sample originally consisted of 132 students from six different schools in greater Munich, of which four were high schools (in the German education system, Gymnasium) and two secondary schools (German: Realschule). Thirty-two students were excluded from the data set, because either their parents did not give their consent or the students did not show up on all relevant dates for various reasons; methodological drop-out effects can be ruled out. Thus, the data are analyzed for 100 participants; 92 students attended Gymnasium and 8 attended Realschule; 36 were in School Year 10, 55 in Year 11, and 9 in Year 12.1 Before the test, only 2 participants reported that they had previous experience with hypnosis; 1 of them named “neurohypnotic anchoring.” Almost one third (29%) reported experiences with relaxation techniques, for example, relaxation exercises introduced in religious education classes, meditation, or yoga. Sex distribution was relatively balanced as 57% of the participants were female and 43% were male; ages ranged from 15.4 to 19.10 years, and the average age was 17.1 (SD = 10.34 months). Participation in the experiment was voluntary. The 1 In

Bavaria, Germany, Year 12 is the students’ last year at school.


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students were informed thoroughly about the experimental conditions at the beginning of the test and could withdraw at any time. Instruments In order to test hypnotizability, the Harvard Group Scale of Hypnotic Susceptibility, Form A (HGSHS:A; Shor & Orne, 1962) was used in the German translation by Bongartz (1985). The HGSHS:A is widely used in research and is a valid measure for group screenings. It consists of 12 pass/fail items (suggestions) with increasing item difficulty (head falling, eye closure, hand lowering, arm immobilization, finger lock, arm rigidity, hands moving toward each other, communication inhibition, hallucination, eye catalepsy, posthypnotic suggestion, and amnesia). According to their scores, subjects are assigned to one of three levels of hypnotizability: low (0–4), medium (5–8), and high (9–12). Bongartz (1985) found a rank-order correlation for item difficulty from .92 to .95 compared to American, Australian, and Canadian samples, showing a high concordance between the four samples and a reliability of .62 for the German scale (compared to .80 for the American, .76 for the Australian, and .84 for the Canadian scales). The concept of hypnotizability and the possibility of measuring it is not without controversy (cf. Kirsch, 1997), especially with regard to the HGSHS:A as a tool for group screenings. To determine its factorial structure, various experiments were conducted (e.g., Piesbergen & Peter, 2006). However, the great advantage of the HGSHS:A is that a large number of participants can be tested simultaneously on a relatively economical basis. Intelligence was tested with the Intelligence Structure Test 2000 R (I–S–T 2000 R) by Amthauer, Brocke, Liepmann, and Beauducel (2001). The test draws on a hierarchical framework model or proto model of research in the structure of intelligence (HPI), which represents a summary of classic intelligence models. It is mainly based on Thurstone’s seven primary factors and, following Cattell, prefixes fluid and crystallized intelligence as higher ranking factors. Alternative models like Carroll’s (1993) or Guilford’s (1967) are characterized as “special forms” of the HPI. In the current study, the short version of basic modules of the I–S–T 2000 R was used for economical reasons. It consists of nine task groups of 20 items each (see Table 1), which measure verbal, numerical, and figural intelligence. For data analysis, raw scores are added up and with the help of norm tables transformed into standard scores, which equal certain IQ scores. The scales of the I–S–T 2000 R show high reliability with Cronbach α values and split-half reliability between .87 and .96. Diverging and converging validity were confirmed by the d2 (Brickenkamp, 1994) and other intelligence tests like the HamburgWechsler-Intelligenztest für Erwachsene-Revision (Tewes, 1991) or the Grundintelligenztest Skala 2 (CFT 20; Weiß, 1997).

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Table 1 Description of the Task Groups of the I–S–T 2000 R According to Amthauer et al.’s (2001) Allocation Task Group

Content


Verbal Intelligence Sentence Completion Verbal Analogies

Sentences are to be completed correctly. “Word equivalences” are to be added. Similarities Two words are to be found that share the same generic term. Numerical Intelligence Numerical Basic arithmetic, root Calculations extractions, fractions, etc. Number Series Number series are to be continued by one element. Arithmetic Missing arithmetic Operators operators are to be inserted into equations. Figural Intelligence Figure Selection Dissected figures are to be assigned to complete figures. Cubes

Die with spots on their planes are to be assigned to identical but rotated die.

Matrices

Matrices displaying figures are to be completed logically.

Example “The opposite of consolation is . . .” small: big = short: ? Café, housing, street, office, garden, quarters 148/4 = ?

2, 5, 8, 11, 14, 17, 20, ? 6?2?3=5

Experimental Design and Procedure After the headmasters of each school had given their consent, the students were informed about the study on a separate day on which an information letter, as well as a consent form for parents or students of full age respectively, were also handed out. Data collection took place from January to July 2012. At the beginning of the actual testing day, students were informed that data were treated anonymously by means of individual personal codes. They were asked to first fill in a form with relevant information on their age, sex, school type, class,



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grades from their last school reports in the subjects of German, mathematics, art, and music, and their career aspirations. This was followed by the intelligence test. Afterward, a questionnaire on personality and attachment types was introduced, which they were asked to complete at home and bring back for the second appointment. (The relation between personality type and career aspiration is discussed in another article; see Prade, Geiger, & Peter, in press.) On that second testing day, hypnotizability was assessed with the HGSHS:A (via a CD recorded by W. Bongartz). For both appointments, two school periods were scheduled, that is, 90 minutes. All tests were done in groups in rooms of the participating schools. The number of participants varied between 3 and 28 students. Groups consisted not only of students of one particular class but were assembled from different classes. Students were initially informed about the procedure of the session and about hypnosis and hypnotizability in general. They were then asked to stay quiet while the CD with the HGSHS:A instructions and suggestions was playing even if they were not be able to follow the suggestions, so that they would not disturb the other participants. In return for their participation, each student received a copy of the journal “Hypnose und Kognition” [Hypnosis and Cognition] (Volume 17, about the history of hypnosis) and sweets. Furthermore, participants were given an e-mail address in case they were interested in their test results on the I–S–T 2000 R (percentile values), which they could ask for with their personal code. Data Analyses SPSS, Version 20, was used for data input and analysis. Data were initially tested for type errors with descriptive statistics and frequency tables. Tests for normal distribution were effected by means of Kolmogorov-Smirnov tests. Due to the fact that these tests are very dependent on the sample size, values of skewness and kurtosis, as well as distribution histograms were also considered. In the following, nonparametric tests were used for nonnormally distributed data and for data that were not at least interval scaled. Pearson’s correlation coefficient was used for interval-scaled data, and Kendalls-tau-b for ordinal-scaled tied values. In addition, the effect size Hedges g was calculated if results were significant (e.g., in t tests). Significances were generally calculated two tailed. The significance level was determined as .05. In order to check for differences in means in independent samples, t tests were used for interval-scaled data (test parameter t), MannWhitney U tests for ordinal-scaled data (test parameter U). Levene’s test was used to check for homogeneity of variance. Multifactorial analyses of variance (ANOVA) were applied for comparisons of means of more than two groups (test parameter F). For an accurate comparison between subgroups, post hoc tests with Bonferroni correction were used. Regarding ordinal-scaled data, comparisons in variance were calculated by means of the Kruskal-Wallis test (test parameter H). The


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“Enter method” (“inclusion”) was used for multiple regression analyses considering all predictors to estimate the dependent variable. The level of measurement was defined as interval scaled for HGSHS:A and I–S–T 2000 R data. The level of measurement was ordinal merely for participants’ self-reports about the depth of trance. If school grades are ordinal or interval scaled is frequently discussed. Strictly speaking, grades (and actually hypnotizability scores too) are ordinal scaled, because differences between the individual marks on the grading scale cannot be interpreted as equal; however, in practice, data are generally treated as interval scaled for that purpose. Descriptive statistics were also calculated for the collected grades, because they merely serve as visualization of data and because the statistical error that occurs remains small. For all subsequent calculations concerning the school grades (comparisons of means and correlations), the level of measurement was assumed to be ordinal and nonparametric tests were used.2 To facilitate understanding of the descriptive statistics for data from the intelligence test I–S–T 2000 R, IQ scores were also reported. However, for calculations with this data, the raw scores were used since substantial loss of information in data is caused by the conversion method suggested in the test manual. Since all participants of the current sample are within the same range of age norms, nothing stood in the way of using the raw scores for data analyses.

Results Hypnotizability The mean of the HGSHS:A results of the 99 participants—because one girl completed only the cover page of the test—is 6.11 (SD = 2.63), resembling Bongartz’s (1985) results. Scores range from 0 to 12, whereas the test value 1 is unrepresented. More than a fifth (21.2%) of the participants can be classified as low hypnotizable (0–4 points), 59.6% as medium (5–8 points), and 19.2% as highly hypnotizable (9–12 points). The nonsignificant Kolmogorov-Smirnov test suggests normal distribution of the data, as do values of skewness (a3 = –.29) and kurtosis (a4 = .18), as well as the histogram of distribution (see Figure 1). Participants who reported previous experiences with hypnosis, relaxation techniques, or both (n = 29; M = 6.72; SD = 2.64) do 2 Further, note that senior classes are graded by points (0–15) instead of marks (1–6), and—most important—points are scaled opposite to marks; 0 represents the worst point value whereas 1 is the best possible mark. Because we collected school marks from Grades 10 through 12 in both types of schools (Gymnasium and Realschule), we needed to transform the scores to enable comparisons. Therefore, points were transformed into decimal numbers (one point equals 0.3 grading keys) so that 14 points represent 1.0, 13 points represent 1.3, etc.



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Figure 1. HGSHS:A score distribution of 99 high school and secondary school students aged between 15 and 19 years (color figure available online).

not show any significantly higher susceptibility scores (T = –1.5; df = 97; p = .14; g = –.33) than participants without such experiences (n = 70; M = 5.86; SD = 2.6). Males (n = 43; M = 6.14; SD = 2.39) and females (n = 56; M = 6.09; SD = 2.82) are almost equally susceptible (T = –.09; df = 97; p = .93; g = –.02). Furthermore, participants’ age does not correlate significantly with their total score in the HGSHS:A (Pearson r = .11, p = .28). However, the total score and participants’ self-reported depth of trance correlate highly significantly (Kendalls-tau-b r = .46, p < .001). Intelligence Data of the I–S–T 2000 R were evaluated for all 100 participants of the current study. Table 2 presents the means (M), standard deviations (SD), skewness, and kurtosis, as well as minimum and maximum values of each of the three scales and of the total value. To facilitate comprehensibility, IQ scores are also reported. With means greater than 100, participants of this study perform on average slightly better than the basic population on all scales with the exception of figural intelligence (definition of IQ scores: M = 100, SD = 15). Minimum and maximum values show intelligence scores far below as well as far above average (< 70 is more than two standard deviations below the mean; > 130 is more than two standard deviations above

318


Table 2 Descriptive Statistics for the I–S–T 2000 R Scales and the Total Score of 100 Students Aged Between 15 and 19 Years IQ score in verbal intelligence

IQ score in numerical intelligence

IQ score in figural intelligence

Total IQ score

100 0 111.19 12.48

100 0 108.75 15.49

100 0 100.92 15.13

100 0 109.87 15.50

−.32 −.37 79.0 142.0

.05 −.17 68.5 143.5

−.06 −.42 62.5 137.5

.12 −.68 77.5 139.0


N Valid Missing Mean Standard deviation Skewness Kurtosis Minimum Maximum

the mean). The Kolmogorov-Smirnov test and histograms of raw-score distribution of the individual scales suggest a sufficiently normal distribution of data. Males and females differ significantly on each scale, except for figural intelligence, while males on average perform better than females. Effect sizes for each comparison are medium (verbal intelligence g = 0.44; total score g = 0.54) or even strong (numerical intelligence g = 0.73). The same results can be reported for comparisons between Gymnasium and Realschule students. Here, significant differences can also be observed with high school students achieving higher results—with the exception of figural intelligence where the difference is not significant—and the effect sizes are even stronger (verbal intelligence g = 1.1; numerical intelligence g = 0.76; total score g = 1.76). Due to the big difference in sample size (Gymnasium students n = 92, Realschule students n = 8), results should be treated with caution. The relationship between age and intelligence is not significant; Pearson’s correlation coefficient for verbal intelligence are r = .06, for numerical intelligence r = .13, and for figural intelligence r = .10 (for the total score r = .13). School Grades With M = 1.98 (n = 99), the students achieved the best grades in art, followed by music (M = 2.21, n = 96), and German (M = 2.53, n = 100); the worst school report grade was in mathematics (M = 3.03, n = 100). Highly significant Kolmogorov-Smirnov tests for all marks as well as histograms of mark distribution show deviations from normal distribution.


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Tables 3 and 4 show that males and females differ significantly in all subjects except for mathematics. Female participants perform better in the subjects German, art, and music and even highly significantly better in the latter two. In mathematics, male participants achieved slightly better marks albeit nonsignificantly. Relationship Between Intelligence and Hypnotizability Table 5 presents the correlations between the subscales of the I–S–T 2000 R, including the total score, and the hypnotizability scores of the HGSHS:A with regard to the whole sample of 99 participants. None of the correlation coefficients were significant, which means that there are no meaningful relationships between scores of the I–S–T Table 3 Descriptive Statistics for Subject Grades of Students Aged Between 15 and 19 Years by Sex Ranksa

Latest school report grade in German Latest school report grade in mathematics Latest school report grade in art Latest school report grade in music a It

Sex

n

Mean Rank

Sum of Ranks

Female Male Total Female Male Total Female Male Total Female Male Total

57 43 100 57 43 100 56 43 99 54 42 96

44.67 58.23

2546.00 2504.00

51.15 49.64

2915.50 2134.50

38.94 64.41

2180.50 2769.50

41.14 57.96

2221.50 2434.50

is to be noticed that smaller numbers indicate better school grades.

Table 4 Differences in Ranks Between the Subject Grades of Students Aged Between 15 and 19 Years by Sex Latest school Latest school report grade Latest school Latest school report grade in report grade report grade in German mathematics in art in music Mann-Whitney U z Asymp. Sig. (2-tailed)

893.00 −2.38 .02

1188.50 −.26 .80

584.50 −4.52 .00

736.50 −3.07 .00

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Table 5 Pearson’s Correlations Between I–S–T 2000 R Scales and HGSHS:A for 99 Students Aged Between 15 and 19 Years I–S–T 2000 R Scales (raw values)


HGSHS:A

Verbal intelligence

Numerical intelligence

Figural intelligence

Total

r = .193 p = .056

r = .074 p = .468

r = .038 p = .710

r = .111 p = .273

2000 R and participants’ hypnotizability with regard to the whole sample. However, having split data according to sex, correlations occur as shown in Table 6. Relationships for male participants are very weak and negative while always positive for female participants. Significant correlations between hypnotizability and verbal intelligence (r = .348, p = .009) as well as total intelligence (r = .288, p = .031) can be observed for females. Thus, the obvious assumption is that sex acts as a moderator between verbal intelligence and hypnotizability and also between total intelligence and hypnotizability. This shall be examined by means of a multiple regression analysis. The relationship between the predictor verbal intelligence and the criterion hypnotizability approaches linearity (p = .056). Since it is given strongly for female participants (p = .009) and only weakened by male participants (p = .450) and since sex presents the variable to be tested for moderation, the relationship is considered sufficient and the condition of linearity as given. The relationship also becomes evident for the predictor sex and the criterion hypnotizability, because both feature characteristics of the dichotomic Table 6 Pearson’s Correlations between I–S–T 2000 R Scales and HGSHS:A of 99 Students Aged Between 15 and 19 Years by Sex I–S–T 2000 R Scales (raw values) Verbal Numerical Figural intelligence intelligence intelligence HGSHS: A male (n = 43)

r = –.118 p = .450 female (n = 57) r = .348 p = .009∗

∗ Significant

r = –.147 p = .348 r = .209 p = .123

correlations with p < .05 (two-tailed).

r = –.158 p = .312 r = .182 p = .180

Total r = –.184 p = .238 r = .288 p = .031∗



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variable sex present different frequency distributions with regard to the hypnotizability scores. The condition of homoscedasticity can also be regarded as fulfilled. Normal distribution of standardized residua is sufficiently given. Table 7 shows the results of the multiple regression analysis. As the interaction between the predictors verbal intelligence and sex is significant, sex is confirmed as a moderator variable. The β weight is highest for the interaction suggesting that it is the best predictor among the three variables used. Yet, β weights and significances of verbal intelligence and sex also present themselves as predictors relevant to the model. The value of adjusted R2 = .06 (f 2 > .35) suggests a strong effect. Also when including total intelligence as a predictor, the condition of linearity is fulfilled for the female participants (p = .03). For the same reasons discussed above, a regression analysis is conducted, although the linearity of the relationship does not become significant if all participants are considered (p = .27). Furthermore, homoscedasticity is given for these predictors. Normal distribution of the standardized residua is sufficiently shown. Table 8 presents the results of the multiple regression analysis. Here, sex is also confirmed as a moderator variable by the significant β weight of the interaction, which in turn presents itself as the best predictor in the model. Yet, sex and total intelligence are also good predictors. Once again, a strong effect is presented by adjusted R2 = .04 (f 2 > .35). Table 7 Regression Analysis to Examine if Sex Presents a Moderator Variable for the Verbal Intelligence and Hypnotizability of 99 High School and Secondary School Students Aged 15 to 19 Years Coefficientsa

Model (Constant) Sex Raw values in “verbal intelligence” Interaction (product term) verbal intelligence and sex a Dependent

Unstandardized Coefficients

Standardized Coefficients

Regression Standard coefficient B error

Beta

t

Sig.

1.077 7.088 .138

1.790 3.373 .048

1.343 .343

.602 .549 2.102 .038 2.853 .005

−.190

.087

−1.423

−2.174 .032

Variable: total HGSHS:A.

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Table 8 Regression Analysis to Examine if Sex Is a Moderator Variable for the Total Intelligence and Hypnotizability of 99 High School and Secondary School Students Aged Between 15 and 19 Years Coefficientsa


Model

Unstandardized Coefficients

Standardized Coefficients

Regression Standard coefficient B error

Beta

(Constant) Sex Total raw values of the I–S–T 2000 R Interaction (product term) total intelligence (raw scores) and sex a Dependent

t

Sig.

2.051 6.700 .039

1.761 2.982 .017

1.269 .307

1.165 .247 2.247 .027 2.338 .021

−.062

.027

−1.370

−2.321 .022

Variable: total HGSHS:A.

Relation Between Hypnotizability and School Grades None of the correlations in Table 9 turn out to be significant. Hence, there are no meaningful relations between hypnotizability scores of the HGSHS:A and school grades in the various subjects, even after differentiating according to sex. Table 9 Correlations Between HGSHS:A Scores and Students Aged 15 To 19 Years

Latest grade in German

Latest grade in mathematics

Latest grade in art

Latest grade in music

Sex

n

male female total male female total male female total male female total

43 56 99 43 56 99 43 55 98 42 53 95

HGSHS:A −.02 −.16 −.10 −.03 −.04 −.04 .02 −.03 −.01 −.03 −.10 −.07


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Discussion After the dearth of research on hypnotizability and intelligence, which lasted almost half a century, we wanted to examine if there was a connection between the two, which had been clearly dismissed by some authors of the 1960s and 1970s (e.g., Hilgard, 1965; Kroger, 1977), and if a potential relationship was sex specific. Therefore, we tested 100 German secondary school students with the I–S–T 2000 R for intelligence and 99 of them with the HGSHS:A for hypnotizability during two sessions that were several weeks apart. In addition, grades of the latest school report were recorded. Age ranged from 15.4 to 19.10 years, mean age was 17.1 and the sex ratio was relatively balanced, with 57% females and 43% males. In contrast to previous findings (e.g., Piesbergen & Peter, 2006; Peter, Hagl, Bazijan, & Piesbergen, 2011; Rudski, Marra, & Graham, 2004), no sex-specific differences in mean hypnotizability could be observed in the current sample of adolescent students (albeit small differences in the distribution of individual test scores existed, which are not discussed here; for more information see Peter, Geiger, Prade, Vogel, & Piesbergen, in press). Furthermore, the frequently examined (e.g., Piesbergen & Peter, 2006) positive relationship between HGSHS:A total score and subjective self-reports about depth of trance was shown. Small differences were also present in intelligence scores—males achieved higher scores than females—and in grades, where the ratio was reversed. The fact that the participants of the current sample showed overall higher IQ scores than the average meets general expectations.3 Regarding the overall sample unselected by sex, our results suggest no significant correlations between the variables of interest, hypnotizability, and intelligence (Table 5) and therefore confirm the general trend of previous research mentioned above. This is based on the weak yet negative correlations for males that neutralize the positive correlations for female participants (Table 6). These positive correlations for females are significant for total intelligence and even highly significant for the subcategory verbal intelligence. This is remarkable and as far as we know a new result in its form and occurrence, albeit Eysenck (1947) speculated accordingly. Since many of the HGSHS:A tasks are of kinesthetic nature and therefore require certain spatial visualization capacity, we would also have expected a connection 3 The manual of the I–S–T 2000 R (Amthauer et al., 2001) specifies that high school students of the same age as our sample perform on average 17 raw score points better than non-high school students. This is about 9 to 10 standard values that in turn equal 13.5 to 15 IQ points. In the manual of the CFT 20–R (Weiß, 2008), which is one of the most frequently used intelligence tests, IQ scores are reported specific to German school types as follows: Gymnasium: 109.2; Realschule: 103.3; secondary modern school: 91.4; Hauptschule (vocational school): 91; special needs school: 77.


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to figural intelligence.4 It is, however, plausible that no relationship is revealed for numerical intelligence but mainly for verbal intelligence, because the production of hypnotic phenomena based on verbal suggestions does not demand any mathematical ability but auditory attention and a certain degree of imaginative processing of semantic contents, which females obviously are more capable of than males (Funke & Vaterrodt, 2009; Hyde, 1981). However, we want to go one step further in explaining these surprising results; a positive correlation between hypnotizability and intelligence can be observed for female participants in contrast to males. In general, it can be assumed that our students were highly motivated, for all of them participated voluntarily and received only small compensation (literature and sweets). In some cases, participation required additional effort such as long waiting periods at school. However, we can only speculate about specific motivational reasons in the overall sample due to the absence of data. If motivation and compliance are contributing factors, how can differences between male and female participants be explained? Female students are generally said to have greater adaptability, better work ethos, and higher achievement motivation than male students, which among other things leads to greater academic success (Cohen, 1998; Diefenbach, 2010). In our study, it is particularly noticeable that male participants achieve higher IQ scores than female participants, yet they receive significantly worse grades in almost all surveyed subjects (see Tables 3 and 4). However, as mean hypnotizability of female and male students is equally high (Mf = 6.14 vs. Mm = 6.09), the more intelligent male participants seem to have motivational deficits that relate to school performance and potentially also affect their behavior during hypnosis experiments. One may also speculate that greater intelligence goes along with greater skepticism and consequently with lower expectations explaining the negative correlation between intelligence and hypnotizability for male students. On the other hand, regarding female participants who also demonstrate better achievements, greater willingness to perform can be assumed. According to expectations, they show significant (or even highly significant) negative correlations between intelligence and school grades, which turn out lower for male participants in almost all areas (not specifically demonstrated in the “Results” section of this article; for more information see Geiger, 2012, p. 63, Table 24). With regard to female students with higher IQ scores, an increased interest, greater compliance, and conformity, sex-specific behaviors may account for the positive correlation between intelligence and hypnotizability—at least for German adolescent students aged between 15 and 19 years. 4 Interestingly, this very relationship is presented by females when intelligence and hypnotizability scores are treated as ordinal data: here, the significance level is only marginally missed by p = .065.



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Yet, why did research on this topic stop in the 1970s? The majority of research on hypnotizability and intelligence mentioned at the beginning dates back to the “classical modern age” (Metzler, 2002), that is, the time of the first two thirds of the twentieth century in which the modern sciences had their breakthrough. In the 1960s, a new awakening takes place. Among other influences, social sciences now become a powerful explanatory factor for the reformation of political and social systems and therewith for new forms of scientific thinking and acting. Individualization processes come more and more to the fore during this paradigm shift: Individual fate in the form of acquired characteristics and therewith one’s future no longer have to be accepted passively but are regarded as shapeable. In that time, social policies dabble in the “improvability” of man. Instead of biological factors, socialization processes become the focus of research. At least since the beginning of the 1970s, it was no longer socioscientific mainstream to do research on factors of character traits. Intelligence as a biological category gains a lower status in comparison with intelligence as a social and acquirable category—similar to hypnotizability and hypnotic susceptibility, respectively. The so-called special-state debate (e.g., Barber, 1969; Kirsch, 2011) and the dispute about the trainability of hypnotizability (e.g., Spanos & Flynn, 1989) are examples of that. This discourse over the nature of hypnosis started in the 1970s and dominated the conversation in the hypnosis community for a quarter of a century. A factor like intelligence, which seems to be characterized as stable, even more so than hypnotizability (Piccione, Hilgard, & Zimbardo, 1989), could no longer find a place in research. This may explain why research on the relationship between hypnotizability and intelligence came to a standstill right in the 1970s. Limitations The most important limitation is the limited age range of our participants; results based on adolescent students aged between 15 and 19 years do not allow assumptions about individuals older or younger than that. We therefore cannot make a generalizable statement about the relationship of hypnotizability and intelligence. This limitation also shows a sociodemographic aspect, which could not be controlled for in our study, because the adolescents we tested belonged to the broad middle class rather than the broad lower class or to the part of the very small upper class. The former are less likely to attend a high school and the latter are more likely to go to private elite boarding schools rather than public state schools (for relationships between academic achievements and family background, see Schnitzlein, 2013). Regarding intelligence, our sample scores about 10 points higher than the norm (IQ M = 100) and therefore once again does not represent the average. Our high school students achieve higher IQ scores than our 8 secondary

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school students, whom strictly speaking we could have excluded from data analyses. However, we decided against that because results do not change significantly through this.


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Intelligenz und Hypnotisierbarkeit : Gibt es einen Zusammenhang? Emilia Geiger, Burkhard Peter, Tanja Prade und Christoph Piesbergen Abstrakt: 100 Sekundarstufenschüler zwischen 15 und 19 Jahren wurden auf Intelligenz und Hypnotisierbarkeit getestet. Es konnten keine Korrelationen für die Gesamtstichprobe, männlich und weiblich, beobachtet werden, da die negativen Korrelationen für männliche Teilnehmer die positiven Korrelationen für die weibliche Untergruppe aufhoben. Letztere sind signifikant für den absoluten Wert der Intelligenz (r = 0,228) und hochsignifikant für die Unterkategorie verbale Intelligenz (r = 0,348), jedoch nichtsignifikant für die Unterkategorien numerische und figurale Intelligenz. Frauen scheinen eher in der Lage zu sein, verbal mitgeteilten semantischen Inhalt imaginativ zu verarbeiten. Außerdem scheinen sie eine höhere Motivation zur Aufgabenlösung zu haben als Männer; zumindest als Jugendliche. Stephanie Reigel, MD Intelligence et susceptibilité hypnotique : Existe-t-il un lien? Emilia Geiger, Burkhard Peter, Tanja Prade et Christoph Piesbergen Résumé: Cent élèves du secondaire, âgés entre 15 et 19 ans, ont subi des tests d’intelligence et de susceptibilité hypnotique. Aucune corrélation n’a été observée pour l’échantillon global non sélectionné en fonction du sexe parce que les corrélations négatives des participants de sexe masculin ont été compensées par les corrélations positives observées pour le souséchantillon composé de filles. Ces résultats sont significatifs pour la valeur totale de l’intelligence (r = .288) et hautement significatifs pour la souscatégorie d’intelligence verbale (r = .348), mais non significatifs pour les sous-catégories d’intelligence numérique et d’intelligence figurale. Les filles semblent avoir plus de faciliter à traiter de façon imaginative le contenu sémantique donné verbalement. Elles semblent aussi avoir une motivation à la tâche plus élevée que les participants de sexe masculin, du moins durant l’adolescence. Johanne Reynault C. Tr. (STIBC) Inteligencia y susceptibilidad hipnótica : ¿Existe una conexión? Emilia Geiger, Burkhard Peter, Tanja Prade, y Christoph Piesbergen Resumen: Se evaluaron la inteligencia y habilidad hipnótica de 92 alumnos de preparatoria y 8 de secundaria, con edades entre 15 y 19 años. No se


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observaron correlaciones en la muestra total sin controlar el sexo de los participantes, porque las correlaciones negativas para los hombres se cancelaron con las correlaciones positivas en la submuestra de las mujeres. Estas resultaron significativas para le puntuación total de inteligencia (r = 0.288) y muy significativas para la subcategoría de inteligencia verbal (r = 0.348), sin embargo no fueron significativas para las subcategorías de inteligencia numérica o de figuras. Las mujeres parecen tener mayor habilidad para procesar imaginativamente contenidos semánticos inducidos verbalmente. También parecen tener mayor motivación hacia la tarea que los hombres -por lo menos durante la adolescencia. Omar Sánchez-Armáss Cappello, PhD Autonomous University of San Luis Potosi, Mexico

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