UC Davis

Whether we are at school, at work, running errands, or pursuing our hobbies, we are faced with tasks that place demands on our cognition. Cognitive demands are a core aspect of everyday life. Adults are sensitive to the cognitive demands of different tasks, and they use this sensitivity to adaptively calibrate their mental effort to the requirements of different tasks. Adults also use cognitive demands to guide their decision-making, typically to take courses of action that allow them to conserve their mental effort by avoiding unnecessary cognitive demands. As children grow up, they gain increasing independence in deciding for themselves which tasks to take on or avoid. Understanding how cognitive demands and how preferences for exerting or avoiding mental effort guide their decisions will be key to understanding cognitive development and children’s behavior. In this dissertation, I present research that begins to chart when children become sensitive to cognitive task demands, when relative cognitive demands guide children’s decisions to take on or avoid tasks, and how responses to different types of cognitive demands change across children’s development. Chapter 1 presents a synthesis of the available evidence, finding that although young children can monitor and adapt behavior according to cognitive task demands, spontaneous cognitive monitoring of demands to guide task selection only begins to arise across middle to late childhood. I build upon frameworks of metacognition to suggest putative cognitive mechanisms that may drive this developmental transition, as well as other social and environmental factors that may contribute to children’s sensitivity and adaptations to cognitive demands. Chapter 2 reports the results of a study designed to test sensitivity and adaptations to cognitive control demands, specifically task switching demands, across development. Participants were familiarized with two different tasks that required them to sort toys based on their color or shape. In one task, the sorting rules switched frequently, creating relatively higher cognitive demands; in another task, the sorting rules repeated frequently, creating lower demands. Like adults, older children aged 10 to 11 years showed sensitivity to these relative differences and avoided the more difficult switching task, as evidenced in their self-reported preferences and task decisions. However, younger children aged 6 to 7 years showed no such sensitivity and selected between the tasks at chance levels. Thus, these findings indicate that sensitivity and adaptive responses to cognitive demands emerges across childhood. Chapter 3 reports the results of a study designed to test whether children are differentially sensitive to specific types of cognitive demands. As children age, they transition from engaging cognitive control more reactively, in the moment, to increasingly engaging control proactively to meet anticipated task demands. Children and adults were familiarized with two different tasks that required them to sort toys based on their color or shape but varied when cognitive control was needed. In one task, a sorting rule appeared prior to the toy, allowing participants to proactively prepare; in the other task, the sorting rule only appeared when the toy to sort appeared, requiring reactive control. Adults and 10-year-old children were sensitive to these differences between tasks, and adults strongly preferred the proactive task, maximizing their response efficiency by preparing to sort toys. Five-year-old children were unaware of these differences between tasks, supporting findings of cognitive demand monitoring emerging across older childhood. However, the subset of younger children who did report differences between tasks preferred the reactive task. These findings suggest that preferred adaptations to cognitive demands differ across development, depending on the type of cognitive task demands and age. Chapter 4 incorporates a different task paradigm, the voluntary task switching paradigm, to assess mental effort avoidance in children and adults. In the voluntary task switching paradigm, participants choose when and how often to switch between tasks across trials. Switching between tasks requires mental effort, even when participants decide for themselves to switch tasks. Across three independent datasets, adults and older children exhibited evidence of decreasing their frequency of switching tasks over time, suggesting that they adaptively avoided cognitive task demands. In contrast, younger children did decrease their frequency of task switching over time, suggesting that younger children did not adapt their behavior to avoid cognitive demands. Overall, these findings suggest that older children and adults adapt their behavior in cognitive tasks to avoid cognitive demands but that younger children do not, providing further support for a developmental transition in the sensitivity to and avoidance of cognitive demands across late childhood.