Extraversion-introversion and 8-13 Hz waves in frontal cortical regions

The study examined a possible relationship between electrical activity recorded from the scalp and personality, especially extraversion-introversion, in a sample of 50 male and female volunteers. EEG activity was recorded from 19 electrodes while subjects opened and closed their eyes on instruction. The participants completed Cattell's 16 Personality Factor questionnaire and from those results, second-order personality traits (extraversion-introversion, low anxiety-high anxiety, tough poise-tender mindedness, and subduedness-independence) were calculated. An association was only found between the extraversion-introversion and frontal EEG activity in the 8-13 Hz range. Results also showed that extraverts were at least 3 times more likely to have larger amplitude activity in this range. No significant associations were found in posterior regions of the brain.