Skip to main content

Why you should stop talking to your car

By Clifford Nass, Special to CNN
June 14, 2013 -- Updated 2058 GMT (0458 HKT)
Commuters move slowly in Los Angeles. Studies show that talking to your car's voice technology impairs driving.
Commuters move slowly in Los Angeles. Studies show that talking to your car's voice technology impairs driving.
STORY HIGHLIGHTS
  • Clifford Nass: More of our brain is devoted to speech than anything else; we love to talk
  • Nass: Talking to technology in your car is not natural and it confuses your brain
  • He says even with hands on wheel and eyes on road, talking to your car impairs driving
  • Nass: Your brain works to fill in the blanks talking to an entity you can't see and doesn't listen

Editor's note: Clifford Nass is the Thomas M. Storke Professor at Stanford University and director of the Communication between Humans and Interactive Media (CHIMe) Lab. He is the author of "The Man Who Lied to his Laptop: What Machines Teach Us About Human Relationships," "Wired for Speech" and "The Media Equation."

(CNN) -- Speaking is profoundly human: More of the human brain is devoted to speech than any other activity. People can have an IQ of 50, or a brain that is only one-third the normal size and have difficulties with many simple tasks, but they can speak.

Humans are so tuned to words that from about the age of 18 months, children learn about eight to 10 new words a day, a rate that continues until adolescence.

Humans love to speak: When two hearing people encounter each other, they will speak, despite having other means of communication such as gesturing or drawing. Even when people speak different languages or come from different cultures, they will try to find common words and phrases.

One-day-old infants can distinguish speech from any other sounds and 4-day-olds can distinguish between their native language and other languages. Even in the womb, a fetus can distinguish her or his mother's voice from all other female voices. Adults can distinguish speech sounds at twice the rate of any other sounds, aided by special hair cells in the outer right ear.

See also: Florida anthropologist explains 'baby talk' origins

Clifford Nass
Clifford Nass
Curbing distracted driving
NTSB: No cell phones while driving

Among all animals, only humans have the necessary breathing apparatus and musculature to be able to speak: despite the "Planet of the Apes," no primate could speak like a person, even if their brains grew. Even human ancestors such as the Neanderthal could not possibly speak: speech is a new and remarkably impressive ability.

So, there is nothing so human as speech -- at least until modern technologies came along. Through striking advances in a computer's ability to understand and produce speech, it is common to use your telephone to make airline reservations, answer questions and search the Web.

Because of the shrinking size and increasing speed of computers, it is also possible to speak directly to your automobile.

From putting up with the car intoning, "Your door is ajar," we have moved to navigation systems that can tell you where to find a latte and car interfaces that understand spoken commands and even allow drivers to dictate e-mails, texts and make phone calls.

What could be more simple and natural than talking, even to a technology? And speaking to cars seems particularly desirable. We don't have to take our eyes from the road or our hands from the wheel to select buttons or make choices: Why not let our mouths and our ears do all the work?

Unfortunately, it's not so simple or so desirable.

Recent research by the AAA Foundation for Traffic Safety, conducted by David Strayer at the University of Utah, finds that the new technology can be so distracting it impairs the ability to drive. Studies found that while driving, our attention becomes overloaded by speaking. It basically takes our minds, if not our eyes, off the road.

Here are three reasons why talking while driving is so distracting, and not as safe and effective as you might think:

People like to picture who they are talking with. When you speak with someone face-to-face, you "hear lips and see voices": Your brain automatically and easily focuses on the person.

When you speak on the telephone, you use brainpower to create a mental image of the person you are talking with: The less you know the person, the more mental workload it takes. When you talk to a car, use a phone in a car or dictate a text message, your brain has to do a great deal of work to picture with whom you are communicating. When you're thinking that hard, it's very difficult to pay attention to the road.

That's why talking on a cell phone -- hands free or not -- is much more dangerous than talking to a passenger. The need to imagine steals from attention to the road.

See also: Is hands-free driving just as dangerous?

People want to be understood. Although people love to speak, there are few more frustrating things than someone not listening. Listeners puts a great deal of energy into showing that they are listening: They nod their head, say "uh huh," open their eyes and change their posture. People are built to expect these signals of attention, but cars refuse to provide them.

As a result, drivers become overly concerned with whether the car understands or is even listening, and their attention is again drawn away from the road. In addition, the voice of the car does not have the rich vocal cues that indicate engagement and emotion, providing further evidence that the car isn't understanding.

Cars are not native speakers. When you encounter someone who isn't facile in your language, you have to put a great deal of time into selecting the right words, avoiding idioms and speaking slowly and clearly. Speech is no longer an easy and natural means of communication in these instances.

While it is remarkable that cars can understand something that took billions of years of human evolution, the typical car recognition rate of 85% to 95% makes it a mediocre second-language speaker. As a result, speech becomes effortful and demanding, stealing attention from the road.

Because of these problems, my laboratory and laboratories around the world are trying to find ways to support the driver in creating mental images, in showing that the car wants to understand and enabling the car to understand at levels equal to or even better than a person.

And soon cars will be driving themselves, so that people can ignore the road and multitask their way to fighting for attention from each other, just as they do outside the car.

Watch: The self-driving car changes everything

Follow us on Twitter @CNNOpinion.

Join us on Facebook/CNNOpinion.

The opinions expressed in this commentary are solely those of Clifford Nass.

ADVERTISEMENT
Part of complete coverage on
December 29, 2014 -- Updated 0430 GMT (1230 HKT)
Les Abend: Before we reach a conclusion on the outcome of AirAsia Flight QZ8501, it's important to understand that the details are far too limited to draw a parallel to Flight 370
December 27, 2014 -- Updated 0127 GMT (0927 HKT)
The ability to manipulate media and technology has increasingly become a critical strategic resource, says Jeff Yang.
December 26, 2014 -- Updated 1617 GMT (0017 HKT)
Today's politicians should follow Ronald Reagan's advice and invest in science, research and development, Fareed Zakaria says.
December 26, 2014 -- Updated 1319 GMT (2119 HKT)
Artificial intelligence does not need to be malevolent to be catastrophically dangerous to humanity, writes Greg Scoblete.
December 26, 2014 -- Updated 1505 GMT (2305 HKT)
Historian Douglas Brinkley says a showing of Sony's film in Austin helped keep the city weird -- and spotlighted the heroes who stood up for free expression
December 26, 2014 -- Updated 1303 GMT (2103 HKT)
Tanya Odom that by calling only on women at his press conference, the President made clear why women and people of color should be more visible in boardrooms and conferences
December 27, 2014 -- Updated 2327 GMT (0727 HKT)
When oil spills happen, researchers are faced with the difficult choice of whether to use chemical dispersants, authors say
December 25, 2014 -- Updated 0633 GMT (1433 HKT)
Danny Cevallos says the legislature didn't have to get involved in regulating how people greet each other
December 23, 2014 -- Updated 2312 GMT (0712 HKT)
Marc Harrold suggests a way to move forward after the deaths of NYPD officers Wenjian Liu and Rafael Ramos.
December 24, 2014 -- Updated 1336 GMT (2136 HKT)
Simon Moya-Smith says Mah-hi-vist Goodblanket, who was killed by law enforcement officers, deserves justice.
December 24, 2014 -- Updated 1914 GMT (0314 HKT)
Val Lauder says that for 1,700 years, people have been debating when, and how, to celebrate Christmas
December 23, 2014 -- Updated 2027 GMT (0427 HKT)
Raphael Sperry says architects should change their ethics code to ban involvement in designing torture chambers
December 24, 2014 -- Updated 0335 GMT (1135 HKT)
Paul Callan says Sony is right to call for blocking the tweeting of private emails stolen by hackers
December 23, 2014 -- Updated 1257 GMT (2057 HKT)
As Christmas arrives, eyes turn naturally toward Bethlehem. But have we got our history of Christmas right? Jay Parini explores.
December 23, 2014 -- Updated 0429 GMT (1229 HKT)
The late Joe Cocker somehow found himself among the rock 'n' roll aristocracy who showed up in Woodstock to help administer a collective blessing upon a generation.
December 23, 2014 -- Updated 2115 GMT (0515 HKT)
History may not judge Obama kindly on Syria or even Iraq. But for a lame duck president, he seems to have quacking left to do, says Aaron Miller.
December 23, 2014 -- Updated 1811 GMT (0211 HKT)
Terrorism and WMD -- it's easy to understand why these consistently make the headlines. But small arms can be devastating too, says Rachel Stohl.
December 22, 2014 -- Updated 1808 GMT (0208 HKT)
Ever since "Bridge-gate" threatened to derail Chris Christie's chances for 2016, Jeb Bush has been hinting he might run. Julian Zelizer looks at why he could win.
December 20, 2014 -- Updated 1853 GMT (0253 HKT)
New York's decision to ban hydraulic fracturing was more about politics than good environmental policy, argues Jeremy Carl.
December 20, 2014 -- Updated 2019 GMT (0419 HKT)
On perhaps this year's most compelling drama, the credits have yet to roll. But we still need to learn some cyber lessons to protect America, suggest John McCain.
December 22, 2014 -- Updated 2239 GMT (0639 HKT)
Conservatives know easing the trade embargo with Cuba is good for America. They should just admit it, says Fareed Zakaria.
December 20, 2014 -- Updated 0112 GMT (0912 HKT)
We're a world away from Pakistan in geography, but not in sentiment, writes Donna Brazile.
December 19, 2014 -- Updated 1709 GMT (0109 HKT)
How about a world where we have murderers but no murders? The police still chase down criminals who commit murder, we have trials and justice is handed out...but no one dies.
December 18, 2014 -- Updated 2345 GMT (0745 HKT)
The U.S. must respond to North Korea's alleged hacking of Sony, says Christian Whiton. Failing to do so will only embolden it.
December 19, 2014 -- Updated 2134 GMT (0534 HKT)
President Obama has been flexing his executive muscles lately despite Democrat's losses, writes Gloria Borger
ADVERTISEMENT