Abstract:
A perceived lack of control—the belief that one’s actions don’t determine outcomes—is closely related to uncontrollable stress and helplessness, which may contribute to increased vulnerability to depression. This project examines how perceived uncontrollability influences reward learning and decision-making under uncertainty. Such learning is known to be impaired in stress-related disorders. We manipulated controllability in an fMRI study where 55 participants played a multidimensional probabilistic three-armed bandit task with a hidden target reversal, while simultaneously playing to obtain monetary bonuses or avoid electric shocks. These goal outcomes were determined by performance in controllable games but were unrelated to their actions in uncontrollable games. We found that a lack of control impaired learning after the hidden target reversal had occurred, but only when participants were playing to gain extra money. We also found that people’s subjective belief in the controllability manipulation mediated the extent of their impairment after the reversal in uncontrollable games but not in controllable games. Participants who perceived higher uncontrollability performed worse after reversal when experiencing uncontrollable conditions, and this was independent of goal outcome valence. Next, we used a hidden Markov model to best capture participants’ trial-by-trial choices, then used its estimates to examine the neural correlates of expected value. Activity associated with stimulus onset and the model-derived expected value of the chosen option was observed in the orbitofrontal cortex and striatum, but mean activation and voxel patterns did not differ by controllability or goal outcome valence. Although neural results are negative, our behavioural findings may further our understanding of mechanisms contributing to learning deficits in stress disorders.
