Abstract
OBJECTIVES: There is growing recognition of the value of researching anomalous experiences in the general population to aid our understanding of the psychosis continuum. There are key differences in aims, foci and epistemologies of existing measures, with varying utility for specific research designs. This study addresses gaps in the literature by developing a measure of anomalous experiences with utility for longitudinal (time-sensitive) research, and with particular reliability for people towards the upper (high scoring) end of the continuum. METHODS: An online sample was recruited from the general population to provide questionnaire data for two study parts: (A) item selection and (B) psychometric evaluation. For Part A, both classical test theory and item response theory methods were used to select which items to be included from an initial pool of 57, generated from individuals with persistent anomalous experiences. For Part B, psychometric properties of the resulting measure were evaluated using exploratory and confirmatory factor analysis and tests of reliability and validity. RESULTS: Scores were provided by 532 participants, from which a 19-item scale, the Transpersonal Experiences Questionnaire (TEQ), was developed. The TEQ was found to be a unidimensional scale, with satisfactory internal consistency (0.85), good test-retest reliability and convergent validity. CONCLUSIONS: The TEQ can be used as a unidimensional scale to detect anomalous experiences in the general population, with particular reliability for people with higher incidence of these experiences.