Abstract
Interference between competing motor memories is well-documented in sensorimotor adaptation. Interference is typically assessed using an ABA paradigm wherein participants first adapt to one rotation (Task A), then to an opposite rotation (Task B), and finally are re-exposed to the original rotation (Task A). Interference is observed when performance during the second exposure to Task A is impaired, implying that the motor memory of Task A has been overwritten or masked by the performance of Task B. Previously, we reported that interference is driven by implicit processes because participants exhibited impaired relearning of Task A after adapting to Task B under clamped-feedback conditions (emphasizing implicit processes), but not with delayed-feedback (emphasizing explicit learning). The present study was designed to examine whether memory consolidation, generated by temporal spacing between adaptation sessions, can modulate the interference driven by implicit processes. Participants first adapted to a visuomotor rotation (Task A), returned after 24-hours to complete an opposing clamped rotation (Task B), and then returned another 24-hours later to re-adapt to Task A. It was predicted that the first 24-hr interval would allow for memory consolidation of Task A and reduce the interfering effect of implicit processes. However, results revealed interference during relearning of Task A because there were no differences in performance of Task A between the initial and re-exposure sessions. These findings support the hypothesis that adaptation is particularly susceptible to interference by subsequent implicit learning and highlight the limitations of temporal spacing as a strategy to mitigate interference.
