In addition to conducting these ANOVAs, within each ROI, we conducted one multiple regression analysis for each personality variable that was normally distributed within our sample (i.e., EPI extraversion score, all BFI and UPPS sub-scales, Form V Total and all Form V subscales except Thrill and Adventure Seeking from the Zuckerman Sensation-Seeking Scale). Normality was defined as a skewness value less than 2 times the standard error. Percentage signal change (e.g., between the high- and low-arousal conditions) was the outcome variable, and age, sex, education, sensation-seeking group (dummy-coded), and the personality-measure score were the predictor variables. By using sensation-seeking group as a control variable, these regression analyses revealed what influence these other personality variables had on fMRI signal, beyond the influence of sensation seeking. Finally, we used scores on the ZKPQ Sensation Seeking scale (which was also normally distributed) as a convergent measure of sensation seeking and calculated its correlation with differential activation for high-versus low-arousal stimuli in each ROI.
