Measuring workload with electrodermal activity during common braking actions

How to assess mental load remains a recurrent question. We aimed to explore whether slight differences in real-world driving task demands could be discriminated by electrodermal response (EDR). A sample of 33 participants was observed under five conditions: controlled braking from 50 to 30 km/h, 80 to 50 km/h, 50 to 0 km/h, 80 to 0 km/h, and a single unexpected emergency braking event from 80 to 0 km/h. The likelihood of EDR and, whenever present, its duration were both correlated with workload as represented by the deceleration demand. A higher base travel speed and the unexpected demand of the emergency braking situation impacted EDR, thus attesting higher workload level. EDR explains why stopping the vehicle from 50 km/h and slowing down from 80 to 50 km/h was of similar strain. The results further demonstrate that EDR measures can be successfully employed to discriminate multiple levels of workload. Practitioner Summary: Common braking elicited different loads as revealed by electrodermal response (EDR) with sensitivity to deceleration of − 0.2 g. Even the slightest braking elicited a strain measurable with EDR. Accordingly, EDR may objectively assess the resulting strain during driving, with enhanced reliability if associated with other variables, e.g. cardiac activity.