Thirty female participants were instructed to empathise with 24 male and female photographs displaying positive and negative emotion and to rate each face following its presentation. EEG was recorded from homologous frontal, temporal and occipital sites. Positive and negative facial expressions were differentiated in frontal leads, with greater activation of the left hemisphere during negative mood experience. In higher order interactions, differentiation of positive and negative affect was observed within the right hemisphere in both frontal and temporal leads. However, direction of effect depended on participant personality and on the gender of the face viewed; for temporal EEG, male faces elicited larger inter-hemispheral differences in activation than female faces. Extraversion was associated with widespread enhanced alpha amplitude and neuroticism with greater inter-hemispheral differences in voltage. When rating the photographs, participants with high neuroticism scores rated female faces as more sad than male faces; also the higher the neuroticism score, the higher the standard deviation of overall ratings. The personality data support Eysenck’s claim that extraverts have lower levels of cortical arousal than introverts (Eysenck, 1967). Personality differences in reaction to emotional stimuli reveal that in the field of emotion research, neglect of individual differences is likely to inflate the error term.