Electrophysiological correlates of the perception of visual illusions: an ERP study

• Published in: Nat͡s︡ionalʹnyĭ psikhologicheskiĭ zhurnal Vol. 50; no. 2; pp. 119 - 128
• Main Authors: Denisova, Ekaterina G., Zaitseva, Julia N., Ermakov, Pavel N.
• Format: Journal Article
• Language: English
• Published: 2023
• ISSN: 2079-6617; 2309-9828
• DOI: 10.11621/npj.2023.0209

Background. The question of the psychophysiological mechanisms involved in perception of images containing illusory distortions remains open. There is no record on the specifics of the brain functioning while recognizing various types of illusions. Objective. The aim is to analyse the temporal dynamics of evoked brain activity in relation to the type of perceived illusory distortion. Sample. The empirical study involved a sample of 50 respondents aged 18 to 30 years with normal or corrected vision (83% women). Methods. The method of electroencephalography (registration of evoked potentials, EP) was applied in the study. EEG registration was carried out monopolarly in 32 leads, using a multichannel electroencephalograph Neuroimage‑136 (manufactured by the company “ISS”, Russia). The participants of the experiment were presented with 700 visual images, including 6 groups of various illusions and control images in the form of simple geometric shapes that are not distorted. The stimuli were presented in a randomized order, for a limited time (500 ms). The WinEEG program was used to process EEG recordings. Statistical methods: single-­factor analysis of variance (ANOVA), Dunn’s post-hoc test. Statistical analysis was carried out with the JASP 0.16 software package. Results. Comparison of amplitude dynamics between control stimuli and stimuli with illusory images revealed significant differences in the 200–300 ms interval and in late response components (after 500 ms). As a result of the amplitude analysis of the evoked potentials while recognizing different categories of illusory images, significant differences were noted starting from the interval of 100–200 ms and covering both early and middle components of the response, as well as the late ones. Pairwise comparison showed that space curvature illusions, double images, and movement illusions were significantly different from almost all other groups of stimuli. Conclusion. The characteristics of evoked brain activity are specific to the type of perceived distortion. Data on the dynamics of the amplitude characteristics of evoked potentials in recognition of visual illusions, as well as their comparative analysis for various types of illusions, expand the understanding of the systemic work of the brain on formation of visual images in general and perception errors in particular.