Personal characteristics of susceptibility to Müller-Lyer illusion in schizophrenia spectrum disorders

Abstract

Purpose. Purpose of the study was to evaluate differences of Müller - Lyer illusion manifestation in schizophrenia spectrum disorders (SSD). Although most studies find that individuals with schizophrenia are more susceptible to optical illusion, there is no scientific consensus⁠. There is a lack of understanding whether there is any assoaciation with SSD symptoms [1]. Methodology. Subject group were patients hospitalised at Hospital of Lithuanian University of Health Sciences Kaunas Clinics Psychiatry Clinic. Control group was gathered from Dermatological and Veneral Desease Clinic. Study protocol was approved by Lithuanian University of Health Sciences bioethics centre. Exclusion criteria were any neurological or ophthalmological diseases, which could affect visual manifestation, motor system impairment causing inability to perform test and subject’s refusal. The stimuli consisted of white Müller - Lyer figures displayed according to Brentano pattern in a black background. Inner angles of figures changed from 10o to 350o. Fourty figures were presented during one experiment and each patient carried out 10 experiments. Position of central figures changed randomly and subjects' aim was to place the central element in the exact middle between outer figures. Illusion strength was evaluated as a distance (measured in arc min) between subjects’ chosen position and geometrical center of figure. Each participant received questions about his education, disease duration, treatment duration, number of psychotic episodes and alcohol usage. Statistical analysis performed by professional statistician. Shapiro - Wilks, Kolmogorov – Smirnov, Akaike’s Information Criterion tests were used for statistical analysis and Skew - T distribution was found to be best for testing results. Results. Study group consisted of 20 persons diagnosed with SSD and 20 matched individuals in the control group. We have found there was [...].