Figure 3. (A) Scatterplots of associations between insula activity (BA13, peak in MNI space: −40 −10 20) and age for the peak of the clusters surviving conjunction analysis with an independent regression of extraversion.

Left panel: association between age and insula activity (r = 0.60, p<0.01). Right panel: association between extraversion and insula activity (r = 0.61, p<0.01). (B) Brain regions that mediated the relationship between age and extraversion. Parameter estimates (risk-taking > safe contrast) extracted at the region identified by conjunction analyses were independently regressed by age and psychological properties. Mediation tests were based on methods described by Shrout and Bolger (2002) and Baron and Kenny (1986). (a) Regression slope of age predicting neural activity; (b) regression slope of neural activity predicting extraversion, controlling for age; (c) regression slope of age predicting extraversion; (c’) regression slope of age predicting extraversion, controlling for neural activity. Bootstrapping was used to estimate indirect effects (Shrout & Bolger, 2002; see also Preacher & Hayes, 2004). A confidence interval that does not overlap with zero indicates statistically significant mediation. *Indicates significant difference from zero, p<0.05. Coordinates are given in MNI space.