Expected reward value and reward prediction errors reinforce but also interfere with human time perception

Time perception is often investigated using instrumental paradigms where reinforcement learning and associated dopaminergic processes have modulatory effects. Interval timing, which includes the judgment of relatively short intervals of time (ranging from milliseconds to minutes), has been shown to be modulated by manipulations of striatal dopamine. In reinforcement learning theory, the ‘expected value of reward’ (EV) and ‘reward prediction errors’ (RPEs) are key variables that explain striatal dopaminergic signals of reward processing during instrumental learning. Despite potential common dopaminergic underpinnings, the underlying connection between reinforcement learning processes and interval timing remains relatively underexplored. Herein, we investigated the impact of EV and RPEs on the human reproduction of 1000ms, 3000ms, and 5000ms intervals of time. Our results demonstrate that RPEs – specifically about rewards and not punishments – appear to reinforce performance errors, which effectively interfere with the rate at which reinforced 1000ms intervals – but not 3000ms and 5000ms intervals – are learned. The results of these experiments help clarify the role reinforcements play in interval timing, as well as give insight into the hypothetical mechanisms underlying time perception and the potential shared relationship with reinforcement learning processes.