Multidimensionality of Hallucination-like Experiences: A Factor Structure Refinement of the Launay-Slade Hallucination Scale

Background: Previous research on the multidimensionality of hallucination-like experiences (HLEs) across the psychosis continuum highlights methodological disparities, emphasizing the need for a cautious interpretation of findings and transparent reporting of parameters used in the analysis. Methods: This study aimed to refine the factorial structure of the 16-item Launay-Slade Hallucination Scale (LSHS), enhance methodological clarity, and improve the comparability and generalizability of LSHS factor solutions. To this end, an Exploratory Factor Analysis (EFA) was performed on a large, heterogeneous sample (N = 278) with specified parameters (e.g., estimation procedure) that remain true to data characteristics and assumptions underlying EFA. Results: The results revealed a four-factor structure including "Multisensory HLEs", "Auditory daydreaming", "Vivid thoughts and inner speech”, and "Personified HLEs”. Our investigation introduces a new factor specific to the perceived presence of another person or another voice. This aligns with theories on self-monitoring difficulties associated with an external attribution bias as hallucination proneness (HP) increases across the continuum. Conclusion: The current results provide an opportunity for investigating neurophysiological and neurobehavioral correlates of HP considering highly differentiated individual profiles of HLEs. Future studies should focus on validating the robustness of the four-factor structure derived from this research across diverse samples of the general population (e.g., different age groups and cultural backgrounds). Specified composite scores underlying HLEs could be of additive value when assessing emerging clinical risk on the psychosis continuum.