Talking to your car can drive you to distraction

A new study in the Psychonomic Society’s Cognitive Research: Principles & Implications (CRPI), led by David Strayer and colleagues at the University of Utah, looked into what kinds of interactive media systems for cars are more distracting, and for which demographics, as well as whether a system’s difficulty can be overcome, and how long the effects of distraction linger.

Maybe I’m a Luddite, but I was shocked to learn that my car can read me my text messages, switch to a song I want to hear, or navigate to my apartment. This is the natural progression of things—voice-based media systems in modern cars are becoming more and more common, especially in cars purchased by drivers between 55 and 65.

Interactive features like this seem like a strange development when we know that making a hands-free or hand-held phone call while driving is considered as dangerous as drunk driving. We know that people can’t actually do two things at once, and that switching between tasks slows us down.

We know that people can’t actually do two things at once, and that switching between tasks slows us down.

However, intuitively, language seems easy, especially when talking to a simple machine, so perhaps talking to your car isn’t risky?

Unfortunately, language might not be as easy as it appears. We know that among college-aged drivers, In-Vehicle Information Systems (IVIS) distract drivers as much as talking on a cell phone, or worse.

But just like how talking to Apple’s Siri might be more or less intuitive than talking to Google Now depending on you and your preferences, not all voice systems or drivers are created equal.

The video below is for one particular IVIS and gives you an idea of how they work (if you do not already own an IVIS-equipped car):

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Strayer and colleagues tested 257 participants whose ages ranged from 21 to 70 over a period of one week. The study used 10 different kinds of cars with IVIS installed, each varying in complexity.

On the first day of the study, participants received training, performed six short tasks using the IVIS while driving, and then filled out a questionnaire. For five days afterward, participants filled out a journal to document their experience with the car and the voice system. On the seventh day, participants returned to the lab for a post-test and questionnaire.

The authors measured distraction by having participants drive and answer simple math problems and remember short lists of two to five words and compared that to when drivers used the car’s interactive media system. The authors expected that these two conditions would be worse than the simple driving condition. Drivers’ ages and different cars’ interactive systems could also make the IVIS more distracting, and practice with the voice control system might protect drivers from distraction.

Task switching while driving, even intuitive computer systems, has surprisingly large costs and should be used with caution.

A number of striking findings emerged from the research by Strayer and colleagues. The primary outcome the study tested was the factors that influenced workload, which is a multidimensional measure that includes speed, accuracy, and subjective ratings of difficulty. The higher the workload, the more taxing the task. The first result was that these interactive vehicle control systems lead to substantial increases in workload when used while driving.

Second, older adults were weighted down by having to use the interactive control system relative to younger adults. An additional worry was that task switching could lead to long-lasting costs, which the authors measured by how slowly drivers reacted when they did not have any other additional task. The cognitive burden of task switching persisted for up to nine seconds after the task was over, suggesting that IVIS systems can have lasting effects on our attention. This also suggests that stopping use of the systems can still impair drivers for surprisingly long distances. (At 60mph [100km/h], 9 seconds translates into roughly 250-300 yards [meters]).

Finally, the amount of practice with the system did not make the increased difficulty of driving and using the IVIS any smaller, and even relatively easy systems still negatively impacted drivers’ attention.

The message is clear – it is harder to drive when we are talking to others on cell phones, hand-held or otherwise, and no matter to a passenger or to an in-vehicle command system. Task switching while driving, even intuitive computer systems, has surprisingly large costs and should be used with caution. These interactive systems seem to be driving distraction, rather than reducing distracted driving.

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Cassandra Jacobs

Cassandra Jacobs is a graduate student in Psychology at the University of Illinois. Before this, she was a student of linguistics, psychology, and French at the University of Texas, where she worked under Zenzi Griffin and Colin Bannard.

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