The dimensionality of trauma: a multidimensional scaling comparison of police officers with and without posttraumatic stress disorder

This study assesses the multidimensional structure of traumatic events as p erceived by police officers and investigates individual differences in the scaling of such perceptions. Forty-two police officers with posttraumatic s tress disorder (PTSD) and 40 officers without PTSD were given descriptions of critical incidents they were likely to encounter at work. They sorted th ese on the basis of similarity and rated them on 15 descriptive scales. The two groups were comparable in terms of relevant background characteristics . PTSD was diagnosed with the Structured Interview (SI-PTSD). The similarit y data were subjected to individual differences multidimensional scaling an alysis [Carroll and Chang, Psychometrika 35 (1970) 283]. The objective was, first, to identify the basic cognitive dimensions of psychological trauma that police officers use in discriminating between common critical incident s and, second, to test whether officers with and without PTSD apply such di mensions differently when interpreting critical incidents. The same three-d imensional solution was obtained for both groups: (1) emotional reactivity; (2) vulnerability and physical integrity; and (3) moral responsibility. Si gnificant differences were found between the PTSD and non-PTSD groups in th e salience of Dimension 2. Results are discussed with reference to other st udies that address the meaning and interpretation of traumatic events. Impl ications for the conceptualization and assessment of trauma and PTSD are ou tlined. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.