Adolescents flexibly adapt action selection based on controllability inferences

From early in life, we encounter both controllable environments, in which our actions can causally influence the reward outcomes we experience, and uncontrollable environments, in which they cannot. Environmental controllability is theoretically proposed to exert an organizing influence on our behavior. In controllable contexts, we can learn to proactively identify and select instrumental actions that bring about desired outcomes. In uncontrollable environments, we can instead rely on simpler Pavlovian learning processes that enable hard-wired reflexive reactions to anticipated, motivationally salient events. Recent empirical work has demonstrated that adults exhibit flexible controllability-dependent arbitration between instrumental and Pavlovian learning systems. In this study, we examined how the flexible arbitration between learning systems based on the degree of environmental controllability changes from childhood to adulthood. Based on prior empirical findings from a cross-species literature, we hypothesized that adolescents’ action selection may be particularly sensitive to environmental controllability. Ninety participants, aged 8-27, performed a probabilistic learning task that enables estimation of the degree of Pavlovian bias on instrumental learning. Participants completed the task in both controllable and uncontrollable conditions. We fit participants’ data with a reinforcement learning model in which controllability inferences adaptively modulate the dominance of Pavlovian versus instrumental control. Relative to children and adults, adolescents exhibited greater flexibility in calibrating the expression of Pavlovian learning biases to the degree of environmental controllability. These findings suggest that adolescence may be a period of heightened sensitivity to environmental reward statistics that organize motivated behavior across the lifespan.