Investigating Factor Structure, Validity, and Reliability of the Persian Version of the Stanford Hypnotic Susceptibility Scale: Form C (SHSS: C)

Objectives The Stanford Hypnotic Susceptibility Scale: Form C (SHSS: C) was first introduced by Weitzenhoffer and Hilgard in 1952 and then revised and completed in 1962. The given scale mainly measures behavioral compliance and suggestibility within a whole range of hypnotic phenomena (movements as well as examples of imagination and cognitive distortions) in a short time. Thus, the purpose of this study was to investigate the psychometric properties of SHSS: C in a non-clinical population.
Methods This descriptive study was conducted on 300 students from different schools of Kermanshah University of Medical Sciences in Iran selected by multi-stage cluster random sampling method and tested via research instruments such as SHSS: C, the Hypnotic Induction Profile (HIP), the Harvard Group Scale of Hypnotic Susceptibility by Spiegel, and the NEO Five-Factor Inventory (NEO-FFI). The data obtained were analyzed using descriptive statistics, correlation coefficient, exploratory factor analysis, Cronbach’s alpha coefficient, and Guttman’s split-half coefficient using the SPSS software version 22.
Results Factor analysis using varimax rotation from the principal component analysis extraction method for the SHSS: C could lead to the extraction of three factors of hypnotic susceptibility talents of perceptive-cognitive abilities, sensory-motor phenomena, cognitive distortions, and post-hypnotic effects. The reliability coefficients (alpha, test-retest, and internal consistency) were also equal to 0.80, 0.75, and 0.74, respectively. Moreover, three types of validity (concurrent, criterion, and correlation between subscales and total scale and inter-correlations) for the HIP, the Harvard Group Scale of Hypnotic Susceptibility by Spiegel, and the NEO-FFI were reported to be 0.89, 0.84, and 0.68, respectively.
Conclusion The results showed that the SHSS: C was endowed with desirable psychometric properties in an Iranian population, and it could be used in research studies on psychology and psychiatry.