Kinematic information availability reveals expertise-related flexibility in prior weighting during action prediction:...

Action prediction is critical for success in fast, interactive sports and depends on integrating contextual priors with moment-to-moment kinematic evidence. However, how these information sources are dynamically weighted under varying information availability remains insufficiently understood. We addressed this question in a table tennis action prediction task by manipulating kinematic information availability (high vs. low) and contextual prior (congruent, incongruent, absent) while recording electroencephalography (EEG) in athletes and non-athletes. Thirty-two table tennis athletes and forty-two non-athletes observed serve clips and predicted the landing location. Behaviorally, athletes showed higher overall accuracy, and congruent priors facilitated performance whereas incongruent priors impaired it. Critically, athletes were less susceptible to misleading priors, particularly when more kinematic information was available, consistent with reliability-based reweighting toward sensory evidence. Cue-locked ERPs revealed reduced P3 amplitudes in athletes, suggesting more efficient processing of prior cues and contextual updating. During kinematic processing, athletes exhibited stronger mu (8-13 Hz) desynchronization and a context-sensitive modulation pattern, mu suppression increased in congruent/high-information trials but was relatively enhanced in low-information trials when priors were incongruent or absent, reflecting adaptive scaling of sensorimotor engagement under uncertainty. Non-athletes showed weaker selectivity. Together, these findings provide time-resolved behavioral and EEG observations compatible with accounts of action prediction that emphasize reliability-weighted integration of prior and kinematic information, and suggest that motor expertise may be associated with greater flexibility in this process.