Fig. 3.

Left caudal middle frontal gray matter volume mediates the age effect on self-initiated elaborative encoding strategies. Mediation model of the relationships between age group, left caudal middle frontal gray matter volume, and elaborative strategy composite scores. The indirect effect of age group on self-initiated elaborative strategy use mediated by gray matter volume was significant. The direct effect of age group on self-initiated elaborative strategy use controlling for gray matter volume was not significant. a = The effect of age group on gray matter volume. b = The effect of gray matter volume on self-initiated elaborative strategy use controlling for the effect of age group. ab = The indirect effect of age group on self-initiated elaborative strategy use mediated by gray matter volume. c’ = The direct effect of age group on self-initiated elaborative strategy use controlling for gray matter volume. PFC = prefrontal cortex.