Human eye-hand coordination relies on internal forward models that predict future states and compensate for sensory delays. During line tracing, the gaze typically leads the hand through predictive saccades, yet the extent to which this predictive window reflects expertise or intrinsic individual traits remains unclear. In this study, I examined eye-hand coordination in professional calligraphers and non-experts performing a controlled line tracing task. The temporal coupling between saccade distance (SD) and pen speed (PS) revealed substantial interpersonal variability: SD-PS peak times ranged from approximately -50 to 400 ms, forming stable, participant-specific predictive windows that were consistent across trials. These predictive windows closely matched each individual's pen catch-up time, indicating that the oculomotor system stabilizes fixation in anticipation of the hand's future velocity rather than relying on reactive pursuit. Neither the spatial indices (mean gaze-pen distance, mean saccade distance) nor the temporal index (SD-PS peak time) differed between calligraphers and non-calligraphers, and none of these predictive parameters correlated with tracing accuracy. These findings suggest that diverse predictive strategies can achieve equivalent performance, consistent with the minimum intervention principle of optimal feedback control. Together, the results indicate that predictive timing in eye-hand coordination reflects a stable, idiosyncratic Predictive Protocol shaped by individual neuromotor constraints rather than by expertise or training history.

翻译：人类的眼手协调依赖于内部前向模型，这些模型能够预测未来状态并补偿感觉延迟。在线条追踪过程中，注视通常通过预测性眼跳引导手部运动，然而这种预测窗口在多大程度上反映专业技能还是内在个体特质，目前尚不清楚。在本研究中，我考察了专业书法家与非专业人士在执行受控线条追踪任务时的眼手协调。眼跳距离与笔速之间的时间耦合揭示了显著的人际差异：SD-PS峰值时间范围约为-50至400毫秒，形成了稳定且具有参与者特异性的预测窗口，该窗口在不同试次间保持一致。这些预测窗口与每位个体的笔迹追赶时间高度匹配，表明眼动系统通过预判手部未来速度来稳定注视定位，而非依赖反应性追踪。无论是空间指标（平均注视-笔尖距离、平均眼跳距离）还是时间指标（SD-PS峰值时间），在书法家与非书法家之间均无显著差异，且这些预测参数均与追踪准确度无关。这些发现表明，不同的预测策略能够实现同等的任务表现，这与最优反馈控制的最小干预原则相一致。综合结果表明，眼手协调中的预测时序反映了一种稳定的、特异性的预测协议，该协议由个体神经运动约束塑造，而非由专业技能或训练经历决定。