Extraversion, neuroticism, and event-related brain potentials in response to emotional stimuli

Following Gray's theory of extraversion-introversion, extraverts should react more strongly to stimuli of reward than to stimuli of punishment, while introverts should be more susceptible to stimuli of punishment than to stimuli of reward. These predictions were tested in two experiments using measures of Event-Related Potentials (ERP) as cortical indicators of differential responses to stimuli of varied emotional valence. In Experiment 1, positive, neutral and negative adjectives were used as conditioned stimuli of reward and punishment. Subjects were involved in a processing task in which attention was either attracted to or drawn away from the emotionality of the stimulus material. An interaction of extraversion, emotional valence of stimuli and processing task was found, but did not meet the predictions. In Experiment 2, a startle probe paradigm was used. Foreground stimulation consisted of emotionally positive, neutral and negative slides. Again, extraverts exhibited higher ERP amplitudes to emotionally positive and negative stimuli compared to neutral ones, whereas introverts did not show a differential effect to the emotional content of the stimuli. Thus, Gray's theory could not be confirmed in either one of the experiments. The results suggest that introverts and extraverts respond to emotional stimuli with different processes of compensatory disfacilitation. This interpretation is closer to the presumptions of Eysenck's theory of extraversion.