What the drivers do and do not tell you: using verbal protocol analysis to investigate driver behaviour in emergency situations

Although task analysis of pedestrian detection can provide us with useful insights into how a driver may behave in emergency situations, the cognitive elements of driver decision-making are less well understood. To assist in the design of future Advanced Driver Assistance Systems, such as Autonomous Emergency Brake systems, it is essential that the cognitive elements of the driving task are better understood. This paper uses verbal protocol analysis in an exploratory fashion to uncover the thought processes underlying behavioural outcomes represented by hard data collected using the Southampton University Driving Simulator. Practitioner Summary: This research assessed the appropriateness of verbal protocol analysis (VPA) in investigating driver behaviour in addition to quantitative data collected using Southampton University's Driving Simulator. VPA proved to be a useful extension tool in validating and enhancing hard data. A number of practical recommendations have been offered to guide future research.