The temporal dynamics of the Stroop effect from childhood to young and older adulthood

It is well admitted that children and older adults tend to show longer response latencies at the Stroop task than young adults. The present study aims at clarifying the rational of such changes from childhood to adulthood and in ageing by comparing the impacted cognitive processes across age groups. More precisely, the aim was to clarify if all processes take more time to be executed, hence implying that longer latencies rely mainly on processing speed or if an additional process lengthens the resolution of the conflict in children and/or older adults. To this aim we recorded brain electrical activity using EEG in school-age children, young and older adults while they performed a classic verbal Stroop task. To decompose the signal in the underlying brain networks, we used microstates analyses and compared congruent, incongruent and neutral trials across the three age-groups. Behaviorally, children and older adults presented longer latencies and larger Stroop effects relative to young adults. The microstates results showed that children tend to present different brain configurations compared to both adult groups, even though some brain configurations remained identical among the three groups. In particular, additional brain networks were involved in children to perform the Stroop task, which party account for the longer latencies in this group. By contrast, in aging the results favor the general slowing hypothesis rather than a decline in a specific process since all involved brain networks were similar in the two adult groups but slowed down in the older one.