Investigating simulator validity by using physiological and cognitive stress indicators

• Validation of physiological and cognitive stress indicators with n = 68 subjects. • Circuit with 23 km length and seven sections. • Mixed-methods approach. • Mixed results on validity; many physiological stress indicators show validity. • Cognitive stress was mostly higher in the simulator. Driving simulators are indispensable tools in modern automotive research and development. However, the transferability of findings to real-world driving, and thus, the validity of simulator-based results, cannot be assumed without empirical validation. In this study, we examined physiological (Galvanic Skin Response-based measures, Electrocardiogram-based measures, salivary cortisol) and cognitive (NASA Task Load Index, Short Stress State Questionnaire, single-item ratings) stress indicators by comparing a real-world driving circuit with seven distinct sections to a medium-fidelity driving simulator, applying a Bayesian analytical approach. The results present a mixed picture, with both absolute and relative validity observed for certain physiological and cognitive stress indicators. Overall, our findings suggest that stress responses in the simulator and real-world driving are comparable, although the simulator was subjectively perceived as more stressful. These results provide valuable insights into the validity of simulators for stress research and underscore the need to consider individual differences, experimental conditions, and methodological approaches in future studies.