Table 5.
Criteria 2 and 3 for SWM total errors Z-scores, cumulative life stress, and prefrontal regions of interest [DV was SWM total errors Z-scores (higher z-score = fewer errors)]
| Variables | Unstandardized regression coefficients, SE, p value | FΔ(df) | R2 change, p values |
|---|---|---|---|
| Model 1 | |||
| Pubertal status | B = 0.009, SE = 0.112, p = 0.937 | FΔ (2,41) = 5.933 | R2Δ = 0.224, p = 0.005 |
| Cumulative life stress | B = −0.245, SE = 0.072, p = 0.002 | ||
| Model 2 | |||
| Pubertal status | B = 0.072, SE = 0.101, p = 0.481 | FΔ (2,39) = 8.037 | R2Δ = 0.226, p = 0.001 |
| Cumulative life stress | B = −0.038, SE = 0.082, p = 0.647 | ||
| Frontal gray matter (left anterior cingulate cluster) | B = 1.37, SE = 0.532, p = 0.014 | ||
| Frontal white matter (right prefrontal white matter cluster) | B = 2.834, SE = 0.925, p = 0.004 |
Criterion 2 requires that the IV (cumulative life stress) is significantly associated with the DV (SWM performance) in the absence of the mediator. Criterion 3 requires that the mediator (prefrontal regions of interest) has a significant unique effect on the DV after adjusting for the IV, and the effect of the IV on the DV is reduced after the addition of the mediator to the model.