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：本文通过在新引入的凝视关系指数（Gaze Relational Index, GRI）指标下，利用真实课堂环境中的移动眼动追踪技术测量视觉信息处理过程，深化了对教师视觉专长的理解。该指标定义为平均注视持续时间与平均注视次数之比。此外，本研究旨在通过展示眼动事件检测算法中用于识别注视与扫视的选定配置（即可变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，通过遵循新手-专家范式（2名新手教师与2名经验丰富的教师），我们发现GRI可作为视觉专长的敏感测量指标。正如假设所示，经验丰富的教师的GRI值较低，表明其更精细的领域特定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，我们发现在眼动研究中，选定的速度阈值参数会改变研究结果，在最坏情况下甚至导致偏差。因此，为确保视觉专长研究结果的可推广性，我们强调必须报告与眼动识别相关的配置参数。