1 Developing Cognitive Control: The Costs and Benefits of Active, Abstract Representations Yuko Munakata, Hannah R. Snyder, and Christopher H. Chatham University of Colorado Boulder Submitted for publication in P. Zelazo & M. Sera (Eds), Developing Cognitive Control Processes: Mechanisms, Implications, and Interventions, Erlbaum. Abstract Children show remarkable developments in their ability to decide when and how to flexibly move between a variety of routine and novel activities. While such developments are viewed as adaptive, they may also come with costs. We consider such trade-offs in the development of increasingly active, abstract goal representations supported by prefrontal cortical regions. These developments support key transitions in children’s increasingly flexible behavior, but are also resource-demanding, with implications for learning, creativity, and training. Keywords: reactive control, proactive control, self-directed control, externally-driven control, perseveration, inhibition “There's no such thing as a free cognitive ability.” Instead, just as in the case of “no free lunch,” there is always a cost even when something appears to be free. Cognitive abilities help us in certain situations, but they come with costs in the sense of hindering us in other situations. For example, being good at maintaining goals in