Raising the Stakes on Cognitive Control: How Variations in Reward Help Regulate Behavior

Humans are capable of responding in specific ways to countless stimuli and situations, as well as initiating a myriad of actions by choice. It is no secret that we need to exert control over all these potential behaviors to get through even our most leisurely days in any kind of organized manner. Much previous research in psychology has shown that external incentives provide essential motivation for the performance of individual behaviors and the making of broader choices. Cognitive control bridges the two by transforming choice outcomes into actual, fruitful behavior. In order to efficiently utilize our mental resources while guiding our behaviors, it would be useful for our control mechanisms to be sensitive to external incentives and regulate exertion of control depending on the importance of the situation.;This dissertation examines the impact of external incentives, specifically reward, on two general functions of control: managing our flexibility in adapting to new task demands, and inhibiting ongoing actions that no longer appear appropriate. Both functions are critical in shaping our behaviors to address the diverse and constantly changing demands of our external environment. Our consideration of rewards not only comprises different levels of absolute reward amounts, but also encompasses their relative, moment-to-moment variations. Chapter 1 of this dissertation examines cognitive control in the practice of task switching. Its findings demonstrate that these relative changes in reward are critical for enhancing cognitive flexibility, and that the same amount of currently available reward can affect flexibility differently depending its own defined purpose as well as how it compares to previously obtained reward. Chapter 2 extends the findings of Chapter 1 to cover perceptual flexibility, demonstrating the essential role of reward variations in enhancing the detection of different types of items in our visual environment. Chapter 3 examines how reward variations modulate our inhibitory abilities, our last line of defense against the execution of inappropriate actions. Taken together, they demonstrate that the impacts of reward pervade our cognitive control mechanisms, and that relative reward variations can enhance even mechanisms left alone by constant high reward.