Impact of repetition on physical and imagined movements

Motor imagery and overt action are proposed to share common planning mechanisms while relying on distinct processes during movement performance. To investigate how repetition affects physical and imagined movements, participants physically or mentally drew paths while avoiding barriers. The barrier orientations were either repeated or different across consecutive trials, and the modality (execution or imagery) of the trials either changed or remained the same for two consecutive trials. Reaction time and movement time were analysed as measures of movement planning and task performance, respectively. Imagined movements produced longer reaction times and movement times than physical movements. Repetition of orientation reduced reaction times in both physical and imagined trials, indicating that trajectory repetition facilitated movement preparation. In contrast, previous trial type influenced reaction times only for physical movements, which were only initiated faster when preceded by another physical trial. Different effects emerged for movement time. Physical movements were faster when the same trajectory was repeated no matter the previous trial type, whereas imagined movements were unaffected by orientation and instead showed shorter durations when preceded by another imagined trial. The

Findings: indicate that physical and imagined movements rely on more similar trajectory representations during the planning stage, but diverge during task performance. While physical movements appear to benefit from the persistence of previously generated movement trajectories, imagined trials seems more influenced by modality-specific cognitive processes. These

Results: provide behavioural support for the Motor-Cognitive model and contribute to understanding how movement repetition influences overt and imagined actions. Public

Significance: Statement Mentally rehearsing a movement is widely used in sport and in rehabilitation, but it remains unclear how closely imagined movements match real ones. We asked participants to draw, or to imagine drawing, paths around obstacles, and found that repeating a path speeded up the preparation of both real and imagined movements, whereas performance itself followed different rules in each case. Mental practice therefore supports movement planning but does not simply substitute for physical practice.