Abstract <p>The aim of the work was to analyze the metrics of inter-subjectsynchronization of the brain’s bioelectrical activity when formingand changing a subjective opinion about a painting during its perception beforeand after a joint discussion in dyads (16 participant dyads). Thestudy was conducted under natural conditions of visiting a contemporaryartist’s solo exhibition, where participants interacted in dyads.EEG was recorded using mobile (wearable) SmartBCI electroencephalographsduring the perception and discussion of paintings. The following metricswere calculated during the initial co-viewing of a painting chosenby one of the dyadic participants, and the viewing of the same paintingafter the discussion: phase locking values (<i>PLV</i>),circular correlation coefficients (<i>CCorr</i>),and coherence (<i>Coh</i>). The analysiswas carried out in the theta (4–8 Hz), alpha-1 (8–10 Hz), alpha-2(10–13 Hz), beta-1 (13–18 Hz), and beta-2 (18–30 Hz) EEG frequency bands.After the discussion of the chosen painting, an increase of theinter-subject synchronization metrics (<i>PLV</i>, <i>CCorr</i>, and <i>Coh</i>)was observed in the alpha-2 and beta-2 frequency bands, while inthe theta and beta-1 bands, there was a generalized decrease insynchronization metrics compared to the prediscussion state, apparentlyreflecting the similarity of emotional perception of the paintingand differences in its cognitive evaluation.</p>