What is the structure of alexithymia? - Modern Test Theory analysis of the Perth Alexithymia Questionnaire

Background – The level of alexithymia affects a person's mental and physical health. Nevertheless, this trait is still measured using problematic measurement tools. The Perth Alexithymia Questionnaire (PAQ) is suitable measuring tool, but no study has examined its psychometric characteristics using Modern Test Theory (MTT). Thus, we aimed to explore psychometric features of the PAQ using MTT and Classical Test Theory.Methods – A sample of Czech adults (n=848,age:M=34.95,SD=11.90,females:81.13%) participated in the survey. We measured alexithymia, empathy, sensory processing sensitivity (SPS), neuroticism, anxiety, and depression. Results – The confirmatory factor analysis provided evidence of the excellent fit of the modified bifactor solution: Reliability of the PAQ was good (omega= 0.70–0.96). Measurement invariance testing revealed that the PAQ measures alexithymia invariantly between people who are single and in partnership. The PAQ items had high discrimination, and their measurement precision was highest in individuals with above-average alexithymia. Higher alexithymia was present in males. Finally, alexithymia was positively associated with depression, anxiety, neuroticism, and also with SPS after neuroticism was taken into account.Conclusions – The PAQ represents reliable and valid instrument for assessing alexithymia.