According to the University of Nottingham, standard deviation of vehicle speed and lane positioning among participants of a simulator test on a ‘level 3’ autonomous car were more pronounced when the vehicle handed back control to the human.

Announcing initial findings of the study at an RAC Foundation event on Monday, Professor Gary Burnett from the University said: “Some people experienced problems in resuming control after a period of not driving”. He added that other participants in the simulator, looking for the accelerator were “not sure if they had their foot on the right pedal”.

RAC Foundation director Steve Gooding described the early results of the study as “worrying”. They should, he added, “provide considerable food for thought for those engaged in the development of these technologies, to chew over whether their adoption is really going to deliver the safety benefits we would all like to achieve”.

Fifty two drivers took part in a 30 minute drive in the simulator for five consecutive days. They activated autonomous control using a voice command when they wanted to and were free to bring their own objects and devices into the car with them, for use when the vehicle was in self driving mode. Bad weather simulated on the penultimate day of the test presented an unexpected takeover request from machine to human.

Eighty percent of participants used a mobile phone during the test. The time spent looking at their devices – as opposed to the road ahead – increased as the week went by. It was also found that the time taken to request automation during the ‘drive’ decreased steadily during the week, indicating an increased level of trust in the technology.

 “We were interested in what sorts of things people will do in these vehicles and what sort of impact that might have, particularly when they needed to regain control,” Gary explained. Some people chose to use their phone, while others read a book or fell asleep. During the week, as participants got more and more exposure to the technology, they became more trusting and accepting of the technology, he added.