People differ in how much they move their head versus their eyes when shifting gaze, yet such tendencies remain largely unexplored in HCI. We introduce head movement tendencies as a fundamental dimension of individual difference in VR and provide a quantitative account of their population-level distribution. Using a 360° video free-viewing dataset (N=87), we model head contributions to gaze shifts with a hinge-based parametric function, revealing a spectrum of strategies from eye-movers to head-movers. We then conduct a user study (N=28) combining 360° video viewing with a short controlled task using gaze targets. While parameter values differ across tasks, individuals show partial alignment in their relative positions within the population, indicating that tendencies are meaningful but shaped by context. Our findings establish head movement tendencies as an important concept for VR and highlight implications for adaptive systems such as foveated rendering, viewport alignment, and multi-user experience design.

翻译：人们在转移视线时头部与眼睛的相对运动程度存在差异，然而这种人机交互中的倾向性尚未得到充分探索。本研究将头部运动倾向确立为虚拟现实中个体差异的基本维度，并对其群体分布进行了量化描述。基于360°视频自由观看数据集（N=87），我们采用基于铰链函数的参数化模型刻画头部对视线转移的贡献度，揭示出从“眼动主导”到“头动主导”的连续策略谱系。随后通过结合360°视频观看与目标注视控制任务的用户研究（N=28）发现：虽然参数值随任务类型变化，但个体在群体中的相对位置呈现部分一致性，表明运动倾向是具有统计意义但受情境调节的行为特征。本研究确立了头部运动倾向作为虚拟现实研究的重要概念，并揭示了其对注视点渲染、视口对齐及多用户体验设计等自适应系统的应用价值。