This article adds to the understanding of teachers' visual expertise by measuring visual information processing in real-world classrooms (mobile eye-tracking) with the newly introduced Gaze Relational Index (GRI) metric, which is defined as the ratio of mean fixation duration to mean fixation number. In addition, the aim was to provide a methodological contribution to future research by showing to what extent the selected configurations (i.e. varying velocity thresholds and fixation merging) of the eye movement event detection algorithm for detecting fixations and saccades influence the results of eye-tracking studies. Our study leads to two important take-home messages: First, by following a novice-expert paradigm (2 novice teachers & 2 experienced teachers), we found that the GRI can serve as a sensitive measure of visual expertise. As hypothesized, experienced teachers' GRI was lower, suggesting that their more fine-graded organization of domain-specific knowledge allows them to fixate more rapidly and frequently in the classroom. Second, we found that the selected velocity threshold parameter alter and, in the worst case, bias the results of an eye-tracking study. Therefore, in the interest of further generalizability of the results within visual expertise research, we emphasize that it is highly important to report configurations that are relevant for the identification of eye movements.

翻译：本文通过引入新提出的注视关系指数（Gaze Relational Index, GRI）指标，结合真实课堂情境下的移动眼动追踪技术测量视觉信息处理，深化了对教师视觉专长的理解。该指数定义为平均注视持续时间与平均注视次数的比率。此外，本研究旨在通过展示用于检测注视和扫视的眼动事件检测算法的不同配置（即变化速度阈值与注视合并）对眼动研究结果的影响程度，为未来研究提供方法论贡献。我们的研究得出两个重要结论：第一，通过新手-专家范式（2名新手教师和2名经验教师）发现，GRI可作为衡量视觉专长的敏感指标。与研究假设一致，经验教师的GRI值较低，表明其更精细化的领域知识组织使其能够在课堂中更快速、更频繁地进行注视。第二，我们发现所选速度阈值参数会改变眼动研究结果，且在极端情况下可能导致偏差。因此，为确保视觉专长研究结果的进一步可推广性，我们强调必须报告与眼动识别相关的关键配置参数。