Reassessing the validity and reliability of the MMPI Alexithymia Scale.
In the past decade, alexithymia has emerged as a heuristically useful personality construct used to explain the pathogenesis of a variety of physical illnesses, including classical psychosomatic diseases, somatization disorders, hypochondriasis, and somatoform pain disorders. Unfortunately, research evaluating the alexithymia construct has been conducted with little attention to assessing the psychometric properties of various scales used to measure it. In two separate studies, we examined various scale and item properties as well as the factor structure and validity of the Minnesota Multiphasic Personality Inventory Alexithymia Scale (MMPI-A), one of the most commonly used scales to assess alexithymia. In Study 1, the 22 items that comprise the MMPI-A were extracted from a computerized MMPI data bank which included separate samples of psychiatric inpatients and outpatients. Poor item-to-scale characteristics and only moderate levels of internal reliability were found for both samples. Factor analysis produced factors that were poorly related to the theoretical domains of the alexithymia construct. In Study 2, we found little support for validity of the scale as those patients identified as alexithymic and nonalexithymic by the MMPI-A did not differ on several theoretically relevant scales. These results question seriously the value of the MMPI-A in investigating the alexithymia construct.
Bagby
R M
RM
Department of Psychology, Clarke Institute of Psychiatry, Toronto, Ontario.
Parker
J D
JD
Taylor
G J
GJ
D000328:Adult; D000342:Affective Symptoms / Q000175:diagnosis / Q000523:psychology*; D005260:Female; D006760:Hospitalization; D006801:Humans; D006998:Hypochondriasis / Q000175:diagnosis / Q000523:psychology; D008950:MMPI / Q000706:statistics & numerical data*; D008297:Male; D001523:Mental Disorders / Q000175:diagnosis / Q000523:psychology*; D011594:Psychometrics; D012803:Sick Role; D013001:Somatoform Disorders / Q000175:diagnosis / Q000523:psychology