Selection of Two Identical Pictures from a Group of Similar Ones II: Changes in Ongoing EEG Activity

Abstract

Abstract The paper presents finding of an experiment the aim of which was to judge the impact of an instant cognitive activity (identical pictures searching) on behavior of ongoing EEG activity. Two types of mental task were used: The first — passive watching of a blank white oval and the second — active searching for identical pictures in a group of similar nine line-drawings of living individuals or inanimate objects filling out the white oval. Presented results showed that higher mental load pertinent to active searching for identical pictures in a group of similar pictures results in the prominent event-related desynchronization (ERD) — the mean Total Power value, a quantitative measure of ERD extent, in comparison with reference level (passive watching) was lower while solving the mental task. The results also showed that the actual mental task performance affects the ERD only at some scalp-recording sites. The mean EEG Total Power significantly decreases at parietal and frontal scalp-recording sites whereas the significant decrease of the Frequency at Maximum Power involves occipital scalp electrodes, too. Our results also demonstrated that some subject’s personality traits (moderation, openness and extraversion) affect the actual decrease/increase in size of Frequency at Maximum Power during active mental task solving. Presented findings point at the high suitability of the ERD method to uncover differences in people’s brain activation patterns when engaged in performing cognitively demanding tasks.