Task-Switch Related Reductions in Neural Distinctiveness in Children and Adults: Commonalities and Differences.

Goal-directed behavior requires the ability to flexibly switch between task sets with changing environmental demands. Switching between tasks generally comes at the cost of slower and less accurate responses. Compared with adults, children often show greater switch costs, presumably reflecting the protracted development of the ability to flexibly update task-set representations. To test whether the distinctiveness of neural task-set representations is more strongly affected by a task switch in children compared with adults, we examined multivoxel patterns of fMRI activation in 88 children (8-11 years, 49 girls, 39 boys) and 52 adults (20-30 years, 27 women, 25 men) during a task-switching paradigm. Using multivariate pattern analysis (MVPA), we investigated whether task-set representations were less distinct on switch than on repeat trials across frontoparietal, cingulo-opercular, and temporo-occipital regions. Children and adults showed lower accuracy and longer response times on switch than on repeat trials. Switch costs were similar across groups. Decoding accuracy was lower on switch than repeat trials, suggesting that switching reduces the distinctiveness of task-set representations. Reliable age differences in switch-related reductions of decoding accuracy were absent. More nuanced analyses using probability measures indicated that the distinctiveness of task sets was more affected by switch demand in children than in adults in a subset of frontal, cingulate, and temporal regions. These results point to a remarkable degree of maturity of neural representations of task-relevant information in late childhood along with more subtle region-specific age differences in the effects of task switching on rule representation.