Most research showing P3AR with externalizing-diagnoses is based on the evoked ERP, which is equivalent to the phase-locked energy associated with all the frequencies comprising P3. In a mediation framework this can be thought of as the “total effect” of EVK on externalizing, corresponding to path c in Figure 1A. Theoretically, a high-degree of PLF is necessary for large values of EVK, but large values of EVK are not necessary for a high-degree of PLF. Hence, we tested the mediation model proposed in Figure 1B where the “total effect” has been partitioned into “direct” (path c’) and “indirect” (paths a and b) effects. Path c’ is computed as the difference between the total effect of EVK (as in Figure 1A) and its indirect effect through PLF, which is the product of a and b. PLF is considered to partially mediate the relationship between EVK and externalizing if a significant reduction in the magnitude of c to c’ occurs; or equivalently, if the indirect effect ab is significantly different from zero.
