Voice-to-Text Driver Distraction Study

New research findings suggest that voice-to-text applications offer no real safety advantage over manual texting.

What’s the Problem?

Distracted driving is a growing problem throughout the nation, and the use of cell phones is recognized as one of the chief causes of driver distraction. Although many states have enacted bans on texting while driving – and considerable resources are devoted to anti-texting public service campaigns – the texting-while-driving problem continues to create dangerous conditions for roadway users. Many drivers have believed that this danger could be lessened through the use of voice-to-text applications (rather than manual texting) but in the absence of research findings, no evidence has been available to support or refute that assumption. And without accurate findings, cities and states are unable to confidently develop effective countermeasures.

What’s the Solution?

No research studies prior to 2013 had actually compared the two texting methods in an actual driving environment, so Christine Yager, an associate transportation researcher, conducted a study to determine if either method was safer than the other. Sponsored by the Southwest Region University Transportation Center, the first-of-its-kind study was based on the performance of 43 research participants driving an actual vehicle on a closed course. Other research efforts have evaluated manual versus voice activated tasks using devices installed in a vehicle, but the TTI analysis is the first to compare voice-to-text and manual texting on a handheld device in an actual driving environment.

How was the study done?

Drivers first navigated the course without any use of cell phones. Each driver then traveled the course three more times performing a series of texting exercises — once using each of two voice-to-text applications (Siri® for the iPhone and Vlingo® for Android), and once texting manually. Researchers then measured the time it took each driver to complete the tasks, and also noted how long it took for the drivers to respond to a light which came on at random intervals during the exercises.

Conclusions

In short, texting drivers may believe they’re being more careful when they use the voice-to-text method, but these new findings suggest that those applications offer no real safety advantage over manual texting if drivers choose to visually confirm the spoken texts. More specific findings from the study included:

• Driver response times were significantly delayed no matter which texting method was used. In each case, drivers took about twice as long to react as they did when they weren’t texting. With slower reaction times, drivers are less able to take action in response to sudden roadway hazards, such as a swerving vehicle or a pedestrian in the street.
• The amount of time that drivers spent looking at the roadway ahead was significantly less when they were texting, no matter which texting method was used.
• For most tasks, manual texting required slightly less time than the voice-to-text method, but driver performance was roughly the same with both.
• Drivers felt less safe when they were texting, but felt safer when using a voice-to-text application than when texting manually, even though driving performance suffered equally with both methods.