Photo: AP

A study last week helped cement something we’ve been well-aware of for some time: humans can be quite inattentive behind the wheel, and that poses a challenge when it comes to self-driving vehicles. We need to be able to quickly take over an autonomous vehicle when prompted, in order to avert any potential accident or issue when driving. And even when we’re not sexting or eating tacos or whatever, we’re bad at that.

The study, conducted by the University of Southampton, reviewed the driving patterns of 26 men and women in situations, with and without a “distracting non-driving secondary task.”


Here’s the upshot: the study found that drivers in “non-critical conditions”—that is, say, when you’re not texting, fiddling with the radio, eating, or, as the study puts it, “normal conditions”—needed 1.9 to 25.7 seconds to assume control of the autonomous vehicle when prompted. Nearly 26 goddamn seconds, and again, that is without the distractions. When participants were distracted, the response time to assume control ranged from 3.17 to 20.99 seconds.

One of the study’s authors, Alexander Eriksson, said that the extensive range of takeover times presents a bevy of challenges when attempting to determine the optimal time to assume control.


“This results in a stressed transition process, whereby drivers may accidentally swerve, make sudden lane changes, or brake harshly,” Eriksson said in a statement. “Such actions are acceptable in safety-critical scenarios when drivers may have to avoid a crash, but could pose a safety hazard for other road users in non-critical situations.”

Using a Jaguar XJ 360 degree simulator equipped with a 10.6" LCD panel, when a Takeover Request was issued, the study says a computer-generated voice told the driver, “Please resume control” while the engine’s speed dial was hidden and replaced with this:

Photo: University of Southhampton

So here’s a question: What the hell was someone doing for 26 seconds before they decided to take the wheel? Off the top of my head, here’s a list of things you could do in 26 seconds while driving:

  • Eat a burger, fast
  • Tweet a few times
  • Unbuckle and climb into the back seat to actively search for your phone after you accidentally dropped it
  • Check your email
  • Obliviously ignore the promt from your vehicle to take control of the damn wheel
  • Crash, because you weren’t paying attention

But Eriksson argued in an email that the long transition time may be due to a wide range of factors, “such as being asked to resume control in a curve, and a driver waiting until the vehicle was back on a straight road.”

“This is perfectly acceptable behaviour in non critical transition as the transition isn’t initiated due to for example a system error,” he said. “But such a range will have to be considered when designing for transitions to manual control.”

The authors asserted their findings should illustrate for autonomous system designers that they should take into consideration the wide range of human responses that exist in response to a takeover prompt—and not on finding an average response time needed. And Eriksson said in a follow up email that the extended response times shown in their study may not be such a bad thing “if it means the drivers will maintain a high level of control of their vehicles when in manual driving, rather than stress to resume control and as a result swerve.”

But 26 seconds really is a damn long time, something illustrated nicely in a summary of the study by Digital Trends:

The range of responses, however, was from 1.97 seconds to 25.75 seconds. So that means that for the subject with the slowest tested takeover time, the car going 70 mph would have traveled just over a half mile before the human regained control. At the median time of 4.56 seconds, the car would have traveled 468 feet, or a little more than one and a half football fields.

In the distracted mode, testing the range in response time wasn’t as great, from 3.17 to 20.99 seconds, with a median time of 6.06 seconds. So in the median takeover time, the car would have gone 622 feet, or more than two football fields, before human takeover. In the slowest response time, the car traveled about 2,155 feet.

We’ve come to realize that drivers are expected to be inattentive idiots—Tesla literally expected it when designing Autopilot, according to NHTS—while being the wheel of an autonomous vehicle, so, it has to make you wonder: What else do you think is important enough to avoid grabbing the wheel for nearly half a minute?

In the meantime, pay attention to the road.