Strange face illusions: A systematic review and quality analysis.

BACKGROUND: Strange face illusions describe a range of visual apparitions that occur when an observer gazes at their image reflected in a mirror or at another person's face in a dimly lit room. The illusory effects range from mild alterations in colour, or contrast, to the perception of distorted facial features, or new strange faces.The current review critically evaluates studies investigating strange face illusions, their methodological quality, and existing interpretations. METHOD: Searches conducted using Scopus, PubMed, ScienceDirect and the grey literature until June 2022 identified 21 studies (N = 1,132; healthy participants n = 1,042; clinical participants n = 90) meeting the inclusion criteria (i.e., providing new empirical evidence relating to strange face illusions). The total sample had a mean age of 28.3 years (SD = 10.31) and two thirds (67 %) of participants tested to date are female. Results are reported using the Preferred Reporting Items for Systematic Reviews and meta-Analyses (PRISMA) guidelines. The review was preregistered at the Open Science Framework (OSF: https://osf.io/ek48d). RESULTS: Pooling data across studies, illusory new strange faces are experienced by 58% (95%CI 48 to 68) of nonclinical participants. Study quality as assessed by the Appraisal Tool for Cross-Sectional Studies (AXIS) revealed that 3/21 (14.28%) studies were rated as high, 9/21 (42.86%) as moderate and 9/21 (42.86%) as low quality. Whilst the items relating specifically to reporting quality scored quite highly, those relating to study design and possible biases were lower and more variable. Overall, study quality accounted for 87% of the variance in reporting rates for strange faces, with higher quality being associated with lower illusion rates. The prevalence of illusions was also significantly greater in samples that were older, had higher proportions of female participants and for the interpersonal dyad (IGDT) compared to the mirror gaze paradigm (MGT). The moderating impact of study quality persisted in a multiple meta-regression involving participant age, paradigm type (IGDT vs MGT) and level of feature distortion. Our review point to the importance of reduced light levels, face stimuli and prolonged eye fixation for strange face illusions to emerge. CONCLUSION: Strange face illusions reliably occur in both mirror-gazing and interpersonal gazing dyad paradigms. Further research of higher quality is required to establish the prevalence and particularly, the mechanisms underpinning strange face illusions.

Self-experience in the early phases of schizophrenia: 5-year follow-up of the Copenhagen Prodromal Study.

Despite the avalanche of empirical data on prodromal/"at risk" conditions, the essential aspects of the vulnerability to the schizophrenia spectrum remain largely unaddressed. We report here the results of the Copenhagen Schizophrenia Prodromal Study, a prospective, observational study of first admission patients in putative state of beginning psychosis (N=151) with a follow-up length of 60 months. At follow-up, the rate of conversion to schizophrenia spectrum diagnosis was 37%, whereas the conversion rate from schizotypal disorder to schizophrenia was 25%. High levels of perplexity and self-disorders baseline scores yielded the best prediction of the subsequent development of schizophrenia spectrum disorders. Escalating transitions within the spectrum (i.e., from schizotypal disorder to schizophrenia) were not associated to any candidate psychopathological predictor.