One of the hallmarks of human cognition is its adaptability and ability to prioritize task demands in order to complete a goal – a concept known as cognitive control. Research has shown that cognitive control develops rapidly over the first decade of life. One of the key control-related developments during childhood is the transition from a heavy reliance on in-the-moment and as-needed control recruitment (known as reactive control) to more planful and sustained control (known as proactive control). This transition has been observed in a small number of studies, but much is still unknown about how this transition takes place, the mechanisms support this change, and whether this change is driven by coincident development of executive functions.

This dissertation examined the development of cognitive control using a cross-sectional design in 79 children – 41 5-year-olds and 38 9-year-olds. To assess cognitive control strategy use, children completed an adapted version of the AX-Continuous Performance Task (AX-CPT) while we recorded electroencephalography (EEG). Children also completed a standardized executive function battery. Results revealed that 5-year-olds relied on reactive cognitive control strategies, while 9-year-olds relied on proactive cognitive control strategies. These behavioral patterns were associated with differential patterns of neural activation in a component known as the P3b. Executive functions were differentially associated with cognitive control strategy use. Specifically, better working memory and inhibitory control skills were related to proactive strategy use and increased context sensitivity. This study is the first to examine behavioral and neural measures of cognitive control strategy use on an AX-CPT task as well as the unique relations between cognitive control strategy and executive functioning.