Psychometric validation of the Dutch translations of the Psychological Insight Questionnaire, the Psychological Insight Scale, and the Emotional Breakthrough Inventory

Background: The Psychological Insight Questionnaire (PIQ), the Emotional BreakthroughInventory (EBI), and the Psychological Insight Scale (PIS) have been developed to assess the subjective effects of psychedelic experiences, in order to better understand the therapeutic mechanism of psychedelic-assisted therapy. This study aimed to evaluate Dutch translations of these questionnaires (the PIQ-NL, the EBI-NL, and the PIS-NL) on their psychometric properties.Methods: A cross-sectional Internet-based survey was completed by 347 participants. Test dimensionality, test-retest reliability, internal consistency, and criterion, concurrent, convergent, discriminant, and incremental validity were assessed.Results: Preliminary evidence was found for unidimensional factor structures of the EBI-NL and the PIS-NL. Several viable factor structures were found for the PIQ-NL. All questionnaires displayed good internal consistency, although subscale scores for the PIQ-NL ought not to be reported due to limited subscale reliability. The PIQ-NL and the EBI-NL displayed good test-retest reliability. All questionnaires showed good criterion validity, good concurrent validity with changes in satisfaction with life, and good discriminant validity with the Dutch Mystical Experiences Questionnaire (MEQ30). The EBI-NL showed poor discriminant validity with the PIQ-NL, and acceptable discriminant validity with the PIS-NL. All questionnaires were better at predicting changes in life satisfaction than the Dutch MEQ30, although the EBI-NL did not contribute unique variance in these predictions beyond the PIQ-NL and the PIS-NL.Implications: These findings suggest the PIQ-NL, the EBI-NL, and the PIS-NL all reliably measure a construct, but the construct validity of these measures needs to be further investigated.