When Tesla Motors enabled the "autopilot" feature on its cars in October, it didn't take long for video to appear of drivers trying crazy things -- none more so than jumping into the passenger seat to leave the car totally in control.
The stunts are stupid but they highlight a concern that some already have with the growing use of autonomous technologies in cars: If a vehicle is driving itself, will the driver still pay attention to the road?
The advice from Tesla is clear: "Remain engaged and aware when autosteer is enabled," and "Keep your hands on the wheel."
But that's easier said than done.
Tesla's autosteer keeps a car in its lane by detecting road markings and works even around bends in the road, so drivers are left watching the scenery pass by.
"We struggle to pay attention; we get bored," said Stephen Casner, a research psychologist at NASA who has spent years studying the effects of autopilot technology in aircraft and is now looking at cars.
Trust in technology
When Google offered its employees the chance to commute to work in a prototype self-driving car, it discovered just that. Drivers quickly stopped paying attention to the road. In one instance, a driver turned to the back seat to search for a phone charger while the car was traveling at 65 miles per hour on a freeway.
"People trust technology very quickly once they see it works. As a result, it’s difficult for them to dip in and out of the task of driving when they are encouraged to switch off and relax," the company said in a recent report.
But drivers can't switch off with current automatic driving technology. While the computer does a pretty good job piloting the car, there are times when it can't figure out what's going on, for example if it loses sight of road markings, and drivers will be quickly required to take over.
Drivers are essentially being told, "We don’t want you to do this, but we want you to pretend you’re doing this," NASA's Casner said. "It’s a weird role to put us in."
When he took a drive on a freeway in an autonomous car, it didn't take him long to become comfortable with the technology. "But the one thing I realized was how vulnerable I was in that situation, should the automation suddenly need me or just quit," he said.
A recent study by the National Highway Traffic Safety Administration (NHTSA) and supported by auto makers found some drivers took as long as 17 seconds to respond to a takeover request from the autonomous control system to resume control of the car. That's time drivers don't have, especially on a fast-moving freeway.
There's plenty of evidence that drivers have trouble staying engaged when driving becomes monotonous or there's nothing for them to do.
Watch drivers at any stop light and you'll see them looking down at their smartphones, while boredom pushes some people to far riskier behavior.
In studies of college students in South Dakota, who spend hours driving conventional cars on long, straight roads with little traffic, multitasking is the norm. Without an obvious need to stay focused on the road, students start texting, studying, watching movies and even having sex, said Cindy Struckman-Johnson, a professor at the University of South Dakota.
"It's amazing there aren't more accidents," she said.
In a 2014 study, a third of men and 9 percent of women surveyed at the university reported engaging in sexual acts while driving. Almost half occurred at speeds between 61 and 80 miles per hour, and over a third reported their cars drifted into another lane, or that they ended up speeding because they weren't paying full attention.
Struckman-Johnson said she's worried that as autopilot systems get better, drivers will fall to more and more distractions and care even less about keeping an eye on the road.
A new type of accident
Autonomous technology is new enough that there don't appear to have been any major accidents yet caused by drivers not paying attention to the road. But they're probably coming.
"In the future, i think we're going to have a particular type of accident related to extreme distraction brought on by the features of autonomous car," said Struckman-Johnson. "The car becomes complicit in the accident."
But when that happens, it's important people don't overreact and conclude that self-driving cars aren't safe, NASA's Casner said. The technology promises to virtually eliminate rear-end collisions -- the most common type of car accident -- and is likely to save lives in other situations.
"There's the fear that there will be the one accident that people will react to, and even though we’ve saved thousands of lives in other categories, there'll be an overreaction because ‘A person was killed by a computer’," he said.
For now, researchers don't have a good answer as to how to keep drivers engaged, aware of traffic conditions and ready to take over after minutes or hours of not having to do anything.
Airlines have battled with the same problem and have yet to come up with an answer, Casner said, despite autopilot having been around for about 30 years. But in an aircraft, pilots often at least have a minute or more to figure out what's happening before the plane is in danger of crashing. Car drivers will often have far less time, hence the worry.
Until vehicles become truly autonomous, and drivers can switch off and not have to worry about doing anything, one answer could be to deliberately create things that the driver has to do, Casner said. But no one has figured out yet what that might be.
For now, Tesla has said it's adjusting its autopilot mode to place restrictions on when it can be used. It hasn't detailed any changes yet, but they will hopefully include a requirement to at least be in the driver's seat while the system is engaged.
"There's been some fairly crazy videos on YouTube," Elon Musk said during Tesla's recent earnings call. "This is not good."