Acclimatizing to automation: Driver workload and stress during partially automated car following in real traffic
DOI: 10.1016/j.trf.2019.07.024
archive: archived pipeline: cataloged
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Summary
This study investigates driver workload and stress during partially automated car following in real traffic, addressing the gap in knowledge regarding driver states in real-world environments compared to simulator-based research. The primary motivation was to determine if workload decreases over time as drivers acclimatize to automation, a phenomenon not adequately captured in previous short-duration on-road studies. The research specifically examined the Tesla Model S Autopilot, a SAE Level 2 system, to assess both subjective and physiological responses during extended highway driving. The experiment involved nine experienced drivers who were naïve to the Tesla system. Participants completed two 32-minute motorway drives on British dual carriageways, following a lead vehicle. The design was counterbalanced: one drive included a secondary detection task where participants pressed a button when passing under bridges, while the other did not. Data collection included continuous physiological monitoring via electrocardiography (heart rate, heart rate variability, respiratory rate) and self-report measures using the NASA Task Load Index (TLX) and the Dundee Stress State Questionnaire (DSSQ). The study tracked manual overrides, lane changes, and detection performance (hit and false alarm rates) throughout the trials. Results indicated that driving with Tesla Autopilot involved low overall workload, with a mean self-reported TLX score of 19% across both drives. A clear acclimatization effect was observed: heart rate and self-reported workload decreased from the first to the second drive, suggesting participants became accustomed to the technology. Specifically, heart rate was lower in the second drive for eight out of nine participants, and SDNN (a marker of mental workload) increased, indicating reduced stress. The secondary detection task did not significantly elevate workload compared to the no-task condition (19% vs. 18% TLX). Participants demonstrated high detection performance, with a mean hit rate of 88% for bridges and a very low false alarm rate of 0.9%. Manual overrides were infrequent, occurring only 13 times total, primarily due to unexpected traffic merges or lack of trust in the system. The findings suggest that partial automation on highways imposes a low cognitive load on experienced drivers, and that initial novelty-related stress diminishes rapidly with exposure. The low workload levels align with previous on-road Tesla studies but contrast with some simulator studies that reported higher loads, possibly due to the absence of physical risk in simulators or the inclusion of critical events. The study implies that while automation reduces driving demands, drivers must remain vigilant for rare system failures, as evidenced by the manual overrides. The results support the notion that acclimatization is a key factor in driver acceptance and safety, highlighting the importance of extended exposure periods in evaluating automated driving systems.
Provenance
The full processing record for this entry. Every stage of this paper's journey through the pipeline is logged — what ran, with which tool and model, how many attempts it took, and when it last completed.
| Stage | Outcome | Tool | Model | Prompt | Attempts | Completed |
|---|---|---|---|---|---|---|
| discover | success | Crossref | — | — | 1 | 2026-08-09 |
| archive | success | openalex | — | — | 5 | 2026-08-09 |
| extract | success | cached | — | — | 4 | 2026-08-23 |
| 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 | qwen3.8-27b-gittensor | summ-v5 | 3 | 2026-08-23 |
| tag | success | vector_similarity | — | — | 10 | 2026-08-11 |
| verify | success | — | — | — | 1 | 2026-08-09 |
Summary generated by qwen3.8-27b-gittensor on 2026-08-23; verification: pending re-verification.
Topics
Ranked by relevance to this paper. Hover a topic for its definition.
- stress driving
- workload measurement
- hands on hands off engagement
- situational awareness
- automation
- automation surprise
Information type
What kind of knowledge this paper contributes, grouped by family — independent of topic (what it is about) and method (how it was studied).
- Empirical Findings: physiological data, self report data, behavioral performance data