Time course for concentrations of oxy- and deoxy-hemoglobin in the right dorsolateral prefrontal cortex (DLPFC) during the (a) time production and (b) button-pressing tasks (control). fNIRS data recorded in channels 1–3 (corresponding to the right DLPFC) were filtered, and the averaged values of the (a) time production and (b) button-pressing tasks are plotted. The boxed area (the 30 s period from 5 to 35 s) indicates the data used in the analyses.