When cars do some of the work for their drivers, the focus of drivers' attention shifts, new research from IIHS and MIT's AgeLab shows.
The researchers looked at how a system that helps identify a parking spot and uses automated steering to maneuver into it influenced where drivers directed their gaze while parallel parking. The 31 volunteers parked a 2010 Lincoln MKS equipped with the Active Park Assist system between two inflatable dummy cars. The drivers parked both with and without Active Park Assist in use. When drivers weren't using the system, parking sensors and a rearview camera were still operational.
When using the automation, drivers spent more time looking at the dashboard and less time looking at the parking spot or at the road in front of or behind them. This was even true when the system was searching for a parking spot but steering wasn't automated.
Drivers parallel parked a Lincoln MKS equipped with Active Park Assist, which alerts the driver to a parking spot and calculates whether the space is big enough. The system steers automatically as the driver moves the car forward and in reverse to maneuver into the spot.
"As manufacturers add more assistance technology and automation to vehicles, it's important to understand how these features affect driver behavior," says David Kidd, an IIHS senior research scientist and lead author of the new study. "In the case of automated parking, some of the changes in glance direction were unexpected."
Active Park Assist helps select a parking space for the driver and then directs the driver to remove his or her hands from the steering wheel. The system steers automatically during the parking process, while the driver moves the car forward and in reverse, as instructed by the system.
Overall, drivers in the study glanced at the parking space less frequently and spent less time looking at it when steering was automated than when it wasn't. At the same time, the proportion of glances and time spent looking at the dashboard display, which contained information from the automation, increased.
The researchers expected that drivers would look at the instrument cluster more and at the vehicle's surroundings less during the actual parking maneuvers, when steering was automated. However, it was surprising that this pattern was even more pronounced when the vehicle was approaching a parking space, even though drivers were in complete control of the vehicle during that phase.
The drivers spent 46 percent of their time looking at the dashboard as they approached an open parking space when using Active Park Assist, compared with just 3 percent when not using it. They also spent less time looking forward and rearward (31 percent and 9 percent, compared with 44 percent and 17 percent without the automation).
During the approach, the system calculates whether the parking space is big enough and alerts the driver with a message in the instrument cluster and an audible chime. Drivers didn't need to constantly monitor the display, but they diverted their attention from the road anyway.
The drivers in the study received detailed instructions on using the system and practiced parking with and without it. Still, as novice users, they may have behaved differently than they would have after long-term use.
"Although we don't yet know how this change in glance behavior affects crash risk, manufacturers should consider how the design of new technologies can affect driver behavior in ways they might not intend," Kidd says.