Development of attentional allocation in the dual task paradigm.

Top-down control over attention was investigated on a dual task in 10-year-olds (N=15) and adults (N=21). The tasks were an auditory digit span (DS) and a simple visual response time (RT) task. In four conditions, participants performed neither (no-task), one (DS or RT only) or both tasks (dual). Dependent variables were DS accuracy, RT and pupillary dilation to digits as an estimate of mental effort. Children's behavioral and psychophysiological responses as a function of sequence length and stimulus position were generally similar to those of adults. Slopes of the functions relating pupillary dilation to memory load were linear and increasing in both groups, shallower in dual than that in DS only and shallower in children than that in adults. Children's behavioral results on the DS task began to diverge from those of adults as task demands shifted from passive retention to active rehearsal, but the children did not appear to try harder to compensate for a lower level of behavioral performance. Taken together, the findings suggest that although children allocated their attention in a similar manner as adults, their top-down control over attention in accordance with task difficulty was not yet fully mature.