Cardiac and electroencephalographic measures of workload associated with secondary tasks while driving

The engagement of drivers in tasks other than driving continues to contribute to road accidents world wide. Numerous methods exist to assess distractions while driving, however, research studies rarely incorporate the use of physiological measures to gauge driver mental workload. Possible differences in the responses to secondary tasks while driving between realand simulated-driving situations are also not fully understood. The present project aimed to explore physiological responses in combination with driving performance to various secondary tasks in real- and simulated-driving situations. The influence of individual differences on driving performance and physiological response to the secondary tasks while driving was also investigated. Physiological measures were more sensitive to changes in demand than driving performance measures and also demonstrated more consistent effects between driving environments. Contrary to expectations the 0.1Hz component of HRV was not really affected by the majority of the secondary task conditions. The time domain measures on the other hand seemed much more sensitive to the alterations in driver load. For the EEG based measures, both alpha and theta power changed based on secondary task conditions and the effects on the two frequency bands were generally in the opposite direction to each other. The results suggested that the use of multiple measures can be beneficial to help interpret driver mental workload associated with dual tasks performance while driving. The present findings also suggested that results obtained in simulated driving situations may not reflect those of real world conditions as accurately as desired, indicating researchers should be cautious in generalising findings from simulators to real world settings. Of the secondary task conditions studied, writing a text messaging was the most detrimental to driving performance and produced the most physiological changes. The negative effects observed with this task are important considering the increasing prevalence of people engaging in such behaviours while driving. The preliminary investigation into the association of individual differences suggests that personality may influence actual driving style and the way people experience different tasks while driving, not just accident involvement as previously indicated. The results confirm the merit of using physiological measures in driving research and suggest more research is required to establish differences between tasks performed in real- and simulated-driving environments. Further investigation into the influence of individual differences such as perceptual style and personality is also warranted.