Twenty-five years with the 20-item Toronto Alexithymia Scale

Objective: Twenty-five years ago, this journal published two articles reporting the development and initial validation of the 20-Item Toronto Alexithymia Scale (TAS-20). Since then the literature on alexithymia has burgeoned with the vast majority of this research using the TAS-20, including multiple language translations of the scale. Method: In this article we review the psychometric literature evaluating various aspects of the reliability and validity of the TAS-20 and examine some of the controversies surrounding the scale and the construct it assesses. We reflect on the ways in which the TAS-20 has advanced the measurement of the construct and theory of alexithymia. We also discuss recent developments and some future directions for the measurement of alexithymia. Results: Although not without some controversy, the preponderance of the accumulated evidence over a 25-year period supports various aspects of the reliability and validity of the TAS-20, including findings from confirmatory factor analytic and convergent and discriminant validity studies which are consistent with Nemiah et al.'s (Nemiah et al., 1976 [3]) and Taylor and colleagues (Taylor et al., 1997 [9]) theoretical formulations and definition of the alexithymia construct. Conclusions: Based on the accumulated empirical evidence of 25 years, we conclude that the TAS-20 is a reliable and valid instrument and accurately reflects and measures the construct as it was originally defined by Nemiah et al. Nemiah et al. (1976) [3] as composed of deficits in affect awareness and expression and pensee operatoire (operational thinking). Clinicians and researchers can use the TAS-20 to confidently measure alexithymia, the roots of which have foundations in psychosomatic medicine.