Although dissociative phenomena are often transient features of mental states, existing measures of dissociation are designed to measure enduring traits. A new present-state self-report measure, sensitive to changes in dissociative states, was therefore developed
and psychometrically validated. Fifty-six items were formulated to measure state features, and sorted according to seven subscales: derealization, depersonalization, identity confusion, identity alteration, conversion, amnesia and hypermnesia. The State
Scale of Dissociation (SSD) was administered with other psychiatric scales (DES, BDI, BAI, SCI-PANSS) to 130 participants with DSM-IV major depressive disorder schizophrenia, alcohol withdrawal, dissociative disorders and controls. In these sample
populations, the SSD was demonstrated as a valid and reliable measure of changes in and the severity of dissociative states. Discriminant validity, content, concurrent, predictive, internal criterion-related, internal construct and convergent validities, and internal consistency and split-half reliability were confirmed statistically. Clinical observations of dissociative states, and their comorbidity with symptoms of depression
and psychotic illness, were confirmed empirically. The SSD, an acceptable, valid and reliable scale measuring state features of dissociation at the time of completion, was obtained. This is a prerequisite for further investigation of correlations between
changes in dissociative states and concurrent physiological parameters.
The full reference of the article is: Krüger C & Mace CJ. 2002. Psychometric validation of the State Scale of Dissociation (SSD). Psychology and Psychotherapy: Theory, Research and Practice (formerly the British Journal of Medical Psychology) 2002; 75(1): 33-51. A postprint version of the article is available below. This article flowed from the first author's doctoral research: Krüger, Christina (1998) The State Scale of Dissociation: Development, psychometric validation, and application in a study of concurrent electro-encephalographic correlates. MD Thesis, University of Warwick, United Kingdom. The full MD thesis is available from the digital repository site of the University of Warwick: http://wrap.warwick.ac.uk/38291/ .