Time Alters Distinct Memories Driven by Sensory Prediction Errors and Task Errors in Sensorimotor Adaptation

Prior learning can impair future learning when the requirements of the two memories conflict, a phenomenon termed anterograde interference. In sensorimotor adaptation, the passage of time between initial and future learning can reduce such interference effects, leading to the interpretation that time consolidates motor memories, protecting motor memories from interference. However, we still do not fully understand how time affects learning, as some studies found no effects of time on interference. One possible explanation for such inconclusive findings is that time has distinct effects on the multiple processes underpinning sensorimotor adaptation, and these processes may compensate for each other's effects on behaviour. Here, we used task manipulations that (1) dissociate adaptation processes driven by task errors from adaptation processes driven by sensory prediction errors and (2) separate the task-error driven adaptation processes into a flexible component that could not be acquired under time-pressure from a less flexible component that could be acquired under time-pressure. Consistent with interpretations from early reports, we found that the passage of time reduced anterograde interference effects in the adaptation component driven by sensory prediction errors. The passage of time between initial and subsequent learning also enhanced components of adaptation driven by task error: enhancing both the flexible, time-consuming component and the inflexible, time-efficient component driven by task errors. Thus, we provide evidence that multiple components of sensorimotor adaptation are sensitive to the passage of time.