Figure 4.

Split-half cross-validation. A, The left panel depicts p maps of the differences in the correlations observed between volume and multitasking performance benefit for the relevant training and the irrelevant training subgroups (Split 1), estimated by a general linear model analysis (corrected for multiple comparisons) using the split-half approach. The correlations in the prefrontal region were significantly stronger for the relevant training subgroup than for the irrelevant training subgroup. The p value maps are thresholded at p < 0.05 (Monte Carlo correction for multiple comparisons). The right panel shows multitasking performance benefit as a function of left rostral DLPFC volume that was originally extracted from the whole-brain analyses (n = 100). As demonstrated, the relevant training group showed an inverse relationship with multitasking performance benefit even with a smaller subset (Split 1, n = 25 per group). B, The left panel shows a similar pattern of clustering using the Split 2 subgroups of the relevant training and the irrelevant training cohorts. The right panel also demonstrates that only the relevant training group shows a relationship between multitasking performance benefit and left rostral DLPFC volume even with reduced sampling (Split 2, n = 25 per group).