Organic chemistry is challenging for novices as it involves a large quantity of organic reactions. Effective learning requires not only profound theoretical knowledge but also the ability to reason about causal mechanisms. This study investigated pre-service chemistry teachers' mechanistic reasoning and the implicit cognitive process. Participants (N = 33) were asked to complete three tasks, which required them to explain chemical phenomena or analyze chemical reactions. This work analyzed the components involved in participants' explanations based on the discourse analysis framework and evaluated the mechanistic reasoning by identifying the causal relationship between different components. An eye-tracking method was employed to recognize the mental activity underlying participants' performance. Four parameters, percentage of dwell time, percentage of fixation count, heat maps, and average pupil size, were used to conduct quantitative analyses on the data collected from the eye-tracker. Each parameter on predefined areas of interest was compared to identify the information that participants paid more attention to and bore more cognitive load while reasoning. The results revealed that pre-service chemistry teachers demonstrate four different types of reasoning in organic chemistry tasks: descriptive, relational, simple causal, and mechanistic reasoning. Pre-service chemistry teachers were more concerned with key information and symbolic representations. It was symbolic representations that increased cognitive load.

有机化学对于新手来说具有挑战性，因为它涉及大量的有机反应。有效的学习不仅需要深厚的理论知识，还需要推理因果机制的能力。本研究调查了职前化学教师的机械推理和内隐认知过程。参与者（N = 33）被要求完成三项任务，要求他们解释化学现象或分析化学反应。这项工作基于话语分析框架分析了参与者解释中涉及的组成部分，并通过识别不同组成部分之间的因果关系来评估机械推理。采用眼球追踪方法来识别参与者表现背后的心理活动。使用停留时间百分比、注视计数百分比、热图和平均瞳孔大小这四个参数对从眼动仪收集的数据进行定量分析。比较预先确定的兴趣领域的每个参数，以确定参与者在推理时更关注并承担更多认知负荷的信息。结果显示，职前化学教师在有机化学任务中展示了四种不同类型的推理：描述性推理、关系性推理、简单因果推理和机械推理。职前化学教师更关心关键信息和符号表示。正是符号表征增加了认知负荷。