Cognitive load during driving: EEG microstate metrics are sensitive to task difficulty and predict safety outcomes

Ma, Siwei; Yan, Xuedong; Billington, Jac; Merat, Natasha; Markkula, Gustav · 2024 · Crossref

DOI: 10.1016/j.aap.2024.107769

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Summary

This study investigates whether EEG microstate analysis can differentiate between varying levels of cognitive load during driving and predict safety outcomes in critical scenarios. While existing EEG methods can distinguish between task and no-task conditions, they often fail to discriminate between different intensities of cognitive load. Furthermore, the predictive value of EEG metrics for safety-critical events, such as rear-end collisions, remains underexplored. The authors address these gaps by applying EEG microstate analysis—a method that categorizes brain activity into quasi-stable functional states—to a driving simulation experiment involving phone use. The experiment involved 34 participants driving in a high-fidelity simulator while engaging in arithmetic tasks of varying difficulty (single- vs. double-digit addition/subtraction) under three phone use conditions: baseline (no phone), hands-free, and handheld. Data were collected during normal driving and a safety-critical stage where the lead vehicle suddenly braked. The researchers analyzed both conventional EEG spectral power (specifically theta band) and EEG microstates (A–D), which correspond to phonological processing, visual processing, default mode, and attention reorientation, respectively. Linear Mixed Models were used to assess the impact of task conditions on EEG metrics and to evaluate whether pre-braking EEG data could predict the minimum time headway achieved during the collision avoidance maneuver. The results demonstrated that conventional EEG spectral power was unaffected by task difficulty, showing no significant differences between conditions. In contrast, EEG microstates were highly sensitive to cognitive load. A distinct pattern emerged where coverage of Microstate A (phonological processing) increased while Microstate D (attention reorientation) decreased as task difficulty escalated. This shift followed a monotonic sequence from baseline to hands-free simple, hands-free complex, handheld simple, and handheld complex tasks. This pattern persisted in both normal driving and critical braking stages. Crucially, EEG microstates recorded prior to the lead vehicle’s braking significantly improved the prediction of safety outcomes (minimum time headway) compared to models using only task difficulty or kinematic data. These findings indicate that EEG microstates provide a more nuanced measure of cognitive load than spectral power, capturing individual differences in how drivers process auditory information at the potential expense of attentional reorientation. The ability of pre-event microstates to predict safety outcomes suggests they reflect brain states indicative of impaired driving performance. This research supports the use of EEG microstate analysis for evaluating the cognitive demands of in-vehicle systems and offers a robust tool for assessing driver safety in real-time, potentially informing the design of personalized driver monitoring and assistance systems.

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StageOutcomeToolModelPromptAttemptsCompleted
discover success Crossref 1 2026-08-09
archive success unpaywall 2 2026-08-09
extract success cached 3 2026-08-10
clean success clean 1 2026-08-09
chunk success chunk 1 2026-08-09
embed success embed Qwen/Qwen3-Embedding-8B 1 2026-08-09
enrich success semantic_scholar 1 2026-08-09
promote success 1 2026-08-09
summarize success llm qwen3.6-27b-nvidia summ-v5 2 2026-08-10
tag success vector_similarity 10 2026-08-11
verify success 2 2026-08-10

Summary generated by qwen3.6-27b-nvidia on 2026-08-10; verification: verified.

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