Vol. 7, Issue 1, Part C (2025)

This paper aims to demonstrate to what extent the Defense Style Questionnaire (DSQ) fulfils the quality criteria of a psychometric test. This topic is controversially discussed in the current research and there is no consensus on the validity of the numerous existing instruments. Therefore, a systematic literature review of the DSQ was conducted. The factorial validity and internal consistency of the DSQ did not or only partially fulfil the criteria of a valid and reliable measurement instrument. The factors analysed in the form of the levels or scales of the DSQ could not be replicated or could only be partially replicated. The same applies to the analysis of reliability. The majority of studies have shown that the DSQ does not reflect the established psychometric properties of a quality instrument. This indicates a lack of content validity within the questionnaire and points out the need for a comprehensive review of existing theories on defense mechanisms.