Language and the development of cognitive control.

We review the relationships between language, inner speech, and cognitive control in children and young adults, focusing on the domain of cognitive flexibility. We address the role that inner speech plays in flexibly shifting between tasks, addressing whether it is used to represent task rules, provide a reminder of task order, or aid in task retrieval. We also consider whether the development of inner speech in childhood serves to drive the development of cognitive flexibility. We conclude that there is a close association between inner speech and cognitive flexibility in both adults and children. Experimental work has begun to specify in detail the role that inner speech might play in adult performance, suggesting that language plays a facilitative but not essential role in representing and activating the relevant task set, processes that occur on both switch and nonswitch trials. While developmental studies suggest an increase in the spontaneous use of verbal strategies with age, implying an increase in top-down control during shifting, experimental work is needed to specify more precisely the nature and precise role that inner speech plays in the development of cognitive control through childhood.