Understanding the Multidimensional and Dynamic Nature of Facial Expressions Based on Indicators for Appraisal Components as Basis for Measuring Drivers' Fear

Zhang, Meng; Ihme, Klas; Drewitz, Uwe; Jipp, Meike · 2021 · Crossref

DOI: 10.3389/fpsyg.2021.622433

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Summary

This study investigates the multidimensional and dynamic nature of facial expressions to improve in-vehicle emotion assessment, specifically focusing on measuring drivers' fear. While facial expressions are commonly used for affective computing in driving contexts, previous approaches often treated emotions as static states, neglecting their temporal evolution and underlying psychological mechanisms. Guided by the Component Process Model (CPM) of emotion, which posits that facial expressions result from a sequential appraisal of situational criteria, the authors aimed to verify if analyzing facial action units (AUs) through the lens of appraisal components could provide a more accurate, dynamic measurement of driver emotions. The researchers conducted a driving simulator experiment with 37 participants using a within-subjects design. Two automated driving scenarios were employed to induce target emotional states: a "fear" condition involving sudden vehicle swerving accidents accompanied by loud noise and distracting text messages, and a "relaxation" baseline condition featuring nature imagery and calming music. Facial expressions were recorded via camera and analyzed using the FACET software to track frame-by-frame activity of specific AUs. Based on CPM predictions, the authors created compound measures for two appraisal components: "high novelty" (AUs 1, 2, 4, 5, and 7) and "low power" (AUs 15, 20, 25, and 26). Self-report questionnaires, including the PANAS and SAM, were used to validate the emotional induction. Statistical analyses, including Wilcoxon tests and pointwise F-tests, compared facial activity and subjective ratings between the fear and baseline conditions. The results confirmed that the experimental manipulation successfully induced fear and relaxation, as evidenced by significant differences in self-reported scores for fear, relaxation, arousal, valence, and novelty. Crucially, the facial expression indicators for high novelty and low power were significantly activated following fear events. The analysis revealed a distinct temporal sequence in these activations: the compound for high novelty showed significant activation from 0 to 2.6 seconds after the fear-inducing event, whereas the compound for low power began activating significantly later, starting at 2.5 seconds and continuing discontinuously until 4.6 seconds. This finding supports the CPM hypothesis that appraisal components drive facial expressions in a fixed sequence, with novelty preceding power. The study concludes that multidimensional analysis of facial expressions, grounded in appraisal theory, is a suitable and valuable approach for in-vehicle emotion measurement. By capturing the dynamic time courses of facial muscle activity, this method offers more nuanced data than static emotion recognition. The ability to detect the sequential activation of appraisal components allows for a deeper understanding of the emotional process, which can inform the development of emotion-aware driving systems. Such systems could adapt automated driving styles or warnings based on the driver's real-time emotional state, potentially enhancing safety and comfort by mitigating negative emotional impacts like fear.

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StageOutcomeToolModelPromptAttemptsCompleted
discover success Crossref 1 2026-06-07
archive success canonical_url 1 2026-06-09
extract success pdftotext 2 2026-06-09
clean success clean 1 2026-06-09
chunk success chunk 1 2026-06-09
embed success embed Qwen/Qwen3-Embedding-8B 1 2026-06-09
promote success 1 2026-06-07
summarize success llm qwen3.6-27b-prismaquant summ-v5 1 2026-06-09
tag success vector_similarity 8 2026-06-11
verify success 1 2026-06-09

Summary generated by qwen3.6-27b-prismaquant on 2026-06-09; verification: verified.

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