Personality and Individual Differences

Regional cerebral blood flow was examined in a group of 17 subjects (8 men, 9 women, ages 22-35) at rest and during three mental activations, inducing perceptual and spatial processing. The subjects completed two personality questionnaires, the Eysenck Personality Inventory and the Karolinska Scales of Personality. The aim of the study was to examine the relation between rCBF and the extraversion-introversion dimension. Earlier studies of rCBF at rest have found higher blood flow in the temporal lobes for introverts than for extraverts, and a negative correlation between extraversion and global cerebral blood flow among women. Both findings were confirmed in this group. The importance of related personality dimensions, such as impulsivity and anxiety, for rCBF differences between extraverts and introverts were examined, using scales from the KSP questionnaire. It was found that anxiety-proneness aspects of introversion were more important in determining high temporal blood flow than low-impulsivity aspects. Global CBF in women, as a measure of general arousal, was mainly related to the sensation-seeking aspects of extraversion. Results from the spatial processing tasks showed more right-hemispheric activation for introverts than extraverts in a mental rotation task.