How Working Memory and Reinforcement Learning Interact when Avoiding Punishment and Pursuing Reward Concurrently

Humans learn adaptive behaviors via a durable but incremental reinforcement-learning (RL) system and a fast but fleeting working memory (WM) system. Past work parsing these systems focused on reward learning alone, hence little is known about how they interact while simultaneously learning to avoid punishment, and whether arbitrating between these demands is disrupted by psychiatric symptoms. We administered a novel reward/punishment RL-WM task to an online sample oversampled for depression and anxiety symptoms (N=298; n=275 after quality control). Participants avoided punishment during initial learning, yet poorly retained this avoidance. Computational modeling captured this pattern via the fleeting WM system facilitating punishment avoidance, while the durable RL system retained little about punishment. Our task also included two test phases interleaved with learning, which permitted a targeted examination of past findings that WM blunts the RL system. When RL-based retention was tested midway through learning, we indeed found evidence of blunting. Yet, after learning resumed—leading to further prediction errors—blunting was no longer evident in a final test phase. However, individual differences moderated this effect: some individuals were especially susceptible to blunting; for others, WM actually facilitated retention. Finally, task performance was largely spared as a function of depression/anxiety and trait rumination. Overall, our findings demonstrate that—when seeking to attain reward and avoiding punishment concurrently—the WM system can facilitate short-term punishment avoidance while the RL system retains little about punishment; reveal individual differences in the extent to which WM blunts RL; and demonstrate intact behavior under internalizing-disorder symptoms.