PERSONALITY AND THE EEG - AROUSAL AND EMOTIONAL AROUSABILITY

Eysenck's theory asserts that low cortical arousal accompanies extraversion (or the subcomponent impulsivity). In Gray's theory, impulsivity is associated with high sensitivity to signals of reward, and anxiety with high sensitivity to signals of punishment. These hypotheses were tested by recording EEG signs of arousal and phasic arousability in emotional imagery, using 17 EEG channels and frequency analysis by Fourier transform. Three conditions were used: a neutral control task, and two emotional conditions involving imagery about pleasant and unpleasant personal memories. Forty subjects participated (23 men, 17 women; median age 23 years). Orthogonal personality dimensions of impulsivity and anxiety were derived from a joint analysis of the EPI and Karolinska Scales of Personality (KSP) questionnaires. The results showed, as expected, lower arousal, defined by more posterior theta activity, in impulsive subjects than in non-impulsives. These differences extended across all conditions. The EEG responses to the emotional conditions, in relation to the neutral one, consisted primarily of a right-lateralized frontal theta increase and changes in temporal beta activity (an increase in the positive condition, and a decrease in the negative one). These responses were expected to be amplified for impulsive subjects in positive emotion, and for anxious subjects in negative emotion. The right-sided frontal theta activity was stronger in high-anxious subjects than in low-anxious ones across all conditions, suggesting higher overall emotionality. For the temporal beta activity, the expected amplification of the response to negative emotion in the high anxiety group was confirmed, but the corresponding prediction for impulsives and positive emotion was not upheld. It is concluded that anxiety is related to EEG signs of heightened emotionality, especially in negative affect, and that impulsivity is associated with lowered arousal.