Automated driving, secondary task performance and situation awareness

This paper describes a study which examined the effect of a demanding non-visual secondary task (Twenty Questions Task) on drivers’ situational awareness during varying levels of vehicle automation. Using the university of Leeds Driving simulator, two groups of drivers (Total N = 50) participated in three separate simulated drives. The driving task was either (i) manual, with drivers in full command of all normal vehicle controls (ii) semi automated, where longitudinal (Group 1) or lateral (Group 2) handling of the vehicle was managed by an automated system or (iii) highly automated, where both lateral and longitudinal control of the vehicle were maintained by the system, which kept the vehicle in the lane centre and maintained a set speed and a safe distance from lead cars. Drivers’ situation awareness was measured in terms of their response to a series of critical incidents in the road. Results showed that, overall, performance measures in the manual condition were different to those in the semi and highly automated drives, and that performance deteriorated in the presence of the higher workload imposed by the secondary task. Interesting differences were also observed between the two semiautomated drives, linked to the driving performance measure under investigation.