Study Reveals How Pedestrians React to Self-Driving Cars

An unusual study has been carried out by academics in the United Kingdom to determine how pedestrians react to autonomous vehicles (AVs) – with a so-called ‘ghost driver’ behind the wheel.

The ‘ghost driver’ was, in fact, a human – Nottingham University research fellow David R. Large – dressed up as a car seat to create the impression that the vehicle was actually driverless.

And the disguise proved effective, with the research illustrating how different exterior displays for the ‘AV’ had an impact on how people perceived it.

Large, a senior research fellow with the university’s human factors research group, explained: “We wanted to explore how pedestrians would interact with a driverless car and developed this unique methodology to explore their reactions. We were keen to identify which designs invited the highest levels of trust by people wanting to cross the road [in front of the ‘AV’].”

The car was driven around the university’s Park Campus over several days to provide an understanding of how pedestrians would respond to self-driving vehicles with different External Human-Machine Interfaces (eHMIs) – visual displays positioned on the front of the vehicle. A series of different designs were projected onto the eHMI, including expressive eyes and a face, accompanied by short messages such as “I have seen you” or “I am giving way.”

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Throughout the test, 520 pedestrians interacted with the car, and 64 responses were recorded via dash cam. Among the reactions noted were how long it took people to cross the road, how often they looked at the car and how long they did so.

And the results were emphatic, as another academic involved in the study, Professor Gary Burnett, explained. 

“We were pleased to see that the external HMI was deemed to be an important factor by a substantial number of respondents when deciding whether or not to cross the road – an encouraging discovery for furthering this type of work,” he said.

Specifically, the eHMI which featured eyes gathered the most attention – mirroring the result of similar research conducted by academics from Japan’s University of Tokyo last year – whereas an LED strip was considered less clear and prompted lower levels of trust. Curiously, it was also noted that several pedestrians used hand signals to acknowledge the ‘AV’ slowing down, despite believing the car was driverless – demonstrating there is still some expectation of social interaction.

It is hoped the findings of the research – which is available to download in full online – might be taken into account as the rollout of self-driving taxi services accelerates in various parts of the world.