An observer scale to measure alexithymia.

The authors developed a relatively brief observer alexithymia measure that can be used by patients' acquaintances and relatives. Items corresponding to the defining features of alexithymia (California Q-Set Alexithymia Prototype) were written, and the new instrument's psychometric properties were evaluated in 3 lay-rater samples. The 33-item Observer Alexithymia Scale (OAS) is internally consistent (coefficient alphas = 0.88 and 0.89) and stable (2-week test-retest reliability = 0.87). Moreover, it has an interpretable five-factor structure (based on exploratory and confirmatory factor analyses): distant, uninsightful, somatizing, humorless, and rigid. The OAS is a reliable instrument with a stable factor structure and good conceptual coverage and thus, it appears to be a useful tool for collecting observer data on the clinically relevant expressions of alexithymia that receive minimal attention.