Development and psychometric evaluation of an informant form of the 20-item Toronto alexithymia scale

Objective: The alexithymia personality construct encompasses difficulties identifying and describing feelings, restricted imaginal processes, and an externally oriented cognitive style. The construct was derived initially from observations of patients with classic psychosomatic diseases. The self-report 20-item Toronto Alexithymia Scale (TAS-20) is the most frequently used measure to assess alexithymia. A concern associated with the TAS-20 is whether individuals can accurately self-report difficulties identifying and describing feelings if they are deficient in those abilities. To address this issue, we sought to develop and validate an informant form (version) of the TAS-20, the 20-item Toronto Alexithymia Scale - Informant Form (TAS-20-IF). Method: We employed a three-phase methodological strategy. In the first phase, items from the TAS-20 were rewritten into a third person version by a team of experts. In the second phase, the "traditional" three-factor structure was tested in the TAS-20-IF using confirmatory factor analysis in a large sample of young adults (N = 857). The third phase was conducted with another sample (N = 430) composed of "informants" (n = 215), who completed the TAS-20-IF, and "targets" (n = 215), who completed the TAS-20 (informants were nominated by the targets). Results: The psychometric properties (items and scales) of both versions were adequate and the three-factor structure of the TAS-20-IF was supported; the correlation between the two versions was statistically significant and the factor structures were similar. Conclusion: Although further research is needed to replicate these findings, especially in clinical samples, the results support the reliability and validity of the TAS-20-IF.