EXTRAVERSION—INTROVERSION AND THE EEG

TLDR

Studies relating measures of the EEG to extraversion–introversion are reviewed and criteria set up for their evaluation. A new measure of mean dominant frequency is proposed. Extravert and introvert EEGs are compared across the whole frequency range (eyes closed) and across theta, alpha, and beta ranges under alternating eyes‑closed/eyes‑open conditions. With eyes closed, extraverts show higher integrated EEG output than introverts across the full range, especially in lower alpha; this alpha difference is less evident with a gross filter but becomes apparent with eyes open under monotonous visual stimulation, and prolonged recordings reveal stronger theta and beta differences, particularly when eyes are shut.

Abstract

Studies relating measures of the EEG to extraversion—introversion are reviewed and criteria set up for their evaluation. A new measure of mean dominant frequency is proposed. Extravert and introvert EEGs are compared, firstly across the whole frequency range (with eyes closed) and secondly across theta, alpha and beta ranges under alternating conditions of eyes closed/eyes open. With the eyes closed, the extravert EEG is higher in integrated output than the introvert EEG across the whole measured range, the differences in output being greater in the lower alpha range. Such differences in alpha are not so readily apparent with eyes closed when recording with a gross filter which fails to discriminate among within‐alpha frequencies. However, with eyes open, and given monotonous visual stimulation, even a gross filter shows differential output. Prolonged recording also reveals differences in theta and beta these differences are stronger when the eyes are shut.