Temporal structure of human gaze dynamics is invariant during free viewing

We investigate the dynamic structure of human gaze and present an experimental study of the frequency components of the change in gaze position over time during free viewing of computer-generated fractal images. We show that changes in gaze position are scale-invariant in time with statistical properties that are characteristic of a random walk process. We quantify and track changes in the temporal structure using a well-defined scaling parameter called the Hurst exponent, H. We find H is robust regardless of the spatial complexity generated by the fractal images. In addition, we find the Hurst exponent is invariant across all participants, including those with distinct changes to higher order visual processes due to neural degeneration. The value we find for H of 0.57 shows that the gaze dynamics during free viewing of fractal images are consistent with a random walk process with persistent movements. Our research suggests the human visual system may have a common strategy that drives the dynamics of human gaze during exploration.

本研究探究人类注视（human gaze）的动态结构，并开展一项实验研究，分析受试者自由观看计算机生成分形图像（fractal images）时，注视位置随时间变化的频率分量特征。研究表明，注视位置的变化在时间维度上具有尺度不变性，其统计特性符合随机游走（random walk）过程的典型特征。本研究采用定义明确的尺度参数——赫斯特指数（Hurst exponent, H），对时间结构的变化进行量化与追踪。研究发现，无论分形图像所产生的空间复杂度如何变化，赫斯特指数均保持稳定。此外，所有受试者的赫斯特指数均保持一致，其中包括因神经退行性病变而出现高级视觉加工过程显著改变的人群。我们测得赫斯特指数H为0.57，这表明受试者自由观看分形图像时的注视动态，与存在持续运动倾向的随机游走过程相符。本研究结果表明，人类视觉系统或许存在一套通用策略，支配探索过程中人类注视行为的动态变化。