Context matters: Protocol ordering effects on physiological arousal and experienced stress during a simulated driving task

Technological advances are increasingly leading us towards a world where vehicles will be able to empathically recognize and respond to the emotional states of their occupants. However, emotion classification algorithms should take account of the dynamic and context-dependent nature of emotional phenomena. The current study sought to examine ordering effects on the evolution of stress at the physiological level. Baseline skin conductivity, blood pressure and heart rate data were recorded for 25 participants, who then completed two tasks in counterbalanced order-a simulated driving task designed to elicit a mild-moderate state of distress, and a comparatively less stressful video-viewing task. Generalized additive models revealed a significant ordering effect, showing that participants who completed the driving task first retained a higher level of physiological arousal during the subsequent relaxation task. Similarly, those who completed the relaxation task first showed a heightened stress response during the simulated drive. These results provide important insights into the temporal evolution of stress at the physiological level in response to contextual factors. This information is likely to be of key interest to those developing models for the automatic detection of stress as it occurs in chanaeable, real-world driving contexts.