Electrophysiological Alterations During Hypnosis for Ego-Enhancement: A Preliminary Investigation

American Journal of Clinical Hypnosis, Apr 2004 by Stevens, Larry, Brady, Brian, Goon, Angela, Adams, Deanna, Et al

Creative Imagination Scale. The CIS is a self-scored, non-authoritarian measure of responses to 10 suggestions (e.g., arm heaviness, hand levitation, finger anesthesia, etc.) which does not require a preceding hypnosis induction (Wilson & Barber, 1978). Each suggestion on the CIS is rated on a Likert scale from 0-4 in terms of the similarity of the imaginai experience to reality, with 4 = "Almost exactly the same". The CIS has been employed in over two decades of research as a measure of waking responsiveness to suggestions. Wilson and Barber (1978) report a test-retest reliability of .82, a split-half reliability of .89, stable factorial validity, and a correlation of .60 between the CIS and another measure of suggestibility, the Barber Suggestibility Scale. CIS scores range from 0-40 and were also negatively skewed for our sample (Skew = .547). Consequently, suggestibility categories were identified by percentile ranges, with low suggestibility = 0-20, moderate suggestibility = 21-28, and high suggestibility = 29-40. This adjusted range of suggestibility differs considerably from one based on normally distributed data but better accommodates the few number of low scores and large number of high scores obtained for our sample.

Stanford Hypnotic Susceptibility Scale: Form C. The SHSS :C is an individually administered test of susceptibility to hypnosis incorporating an hypnotic induction and 12 progressively more difficult challenges (e.g., hand lowering, mosquito hallucination, age regression, amnesia, negative hallucination, etc.; Weitzenhoffer & Hilgard, 1962). Developed by Weitzenhoffer and Hilgard in 1962, the SHSS:C has become widely recognized as the "gold standard" of hypnotic susceptibility testing and contains an improved mix of motoric and cognitive challenges (Perry, Nadon, & Button, 1992; Kurtz & Strube, 1996). Hilgard (1965) reported a Kuder-Richardson total scale reliability index of .85, with item-total correlations from .49-.87, and the correlation between the SHSS:C and its predecessor, the SHSS:A, as .72. Register and Kihlstrom (1986) presented data from a series of studies obtaining correlations from .57 to .62 between the SHSSiC and the Harvard Group Scale of Hypnotic Susceptibility. The SHSS:C has been accepted as having more "top" than other measures of susceptibility, that is, as being more sensitive to very high levels of hypnotic responsiveness (Perry, Nadon, & Button, 1992). Scoring of the Stanford is from 0-12, with the following four susceptibility categories recommended by Hilgard (1965) used in the present study: Low: 0-4; Medium: 5-7; High: 8-10; Very High: 11-12.

Because hypnotizability is a complex, multidimensional personality characteristic comprised of motivational, attitudinal, role-taking, motoric, cognitive, and other behavioral characteristics (Bowers, 1976), Sabourin, et al. (1990) have recommended the identification of hypnotizability levels according to participant responses across multiple measures of hypnotic responsiveness. Following these recommendations, participants were initially categorized on hypnotizability by matching on the SHSS:C and either TAS absorption or CIS suggestibility. However, a comparison of EEG responses for matched participants versus participants categorized on the basis of SHSS:C alone revealed no significant main effect of the matching variable. Consequently, participants were stratified on the basis of the SHSS:C alone in this study.