Christine Yager

Texas A&M Transportation Institute (TTI) Associate Transportation Researcher Christine Yager gave a presentation, “The Effects of Reading and Writing Text-Based Messages While Driving,” at the 56th Annual Meeting of the Human Factors and Ergonomics Society. The meeting was held in Boston, MA, October 22–26 and was attended by more than 1,450 participants from the United States and around the world.

According to Yager, the meeting provided an opportunity for colleagues to share information and research on various human factors topics such as distracted driving, which is a major issue among drivers of all ages. TTI Senior Research Scientist Melissa Walden also attended the meeting.

Yager presented the results of a project that assessed the distraction potential of reading and writing text-based messages while driving under varying roadway and texting response demands.

“I presented the results from our study that looked at the effect of text-based driving,” says Yager. “As part of the presentation I showed three videos that were shot in different experimental conditions: a control, a text-writing, and a text-reading condition.”

Yager says the biggest surprise of the research results was that the response times were even slower than expected compared to previous driving simulator research.

“With the driving simulator, response times were 1–2 seconds, whereas our test track test bed showed an increased response time of 3–4 seconds,” says Yager.

Other notable sessions, according to Yager, were a session about agent-based modeling and how safe-driving information is disseminated among social networks, and a driving simulator research session, which explored the possibility of linking two simulators together to create a virtual driving environment with multiple drivers.

“The area of the conference where Christine presented was specifically related to surface transportation and distracted driving provided a central theme in regards to traffic safety,” says Walden. “It was part of a bigger concern about how advancements in technology can help the driver, but must not adversely affect the driver’s vigilance related to primary driving tasks.”

Additional Resources

Christine Yager Presentation (PDF)

2012 Annual Meeting of the Human Factors and Ergonomics Society website

Texas Transportation Researcher article “It’s Confirmed: Driving’s a Full-Time Job — How Texting Impairs Driving Performance“

TTI research proves that keeping your eyes on the road really does make a difference. Texting while driving was found to double the reaction time of drivers, while myths, such as “texting while driving saves time,” were challenged by the study’s findings.

Federal statistics suggest that distracted driving contributes to as much as 20 percent of all fatal crashes, and that cell phones constitute the primary source of driver distraction. Researchers point to two numbers to illustrate the magnitude of the texting-while-driving problem: an estimated 5 billion text messages are sent each day in the United States, and at least 20 percent of all drivers have admitted to texting while driving.

The study consisted of three major steps. First, participants typed a story of their choice (usually a simple fairy tale) and also read and answered questions related to another story, both on their smart phone in a laboratory setting.

Each participant then navigated a test-track course involving both an open section and a section lined with construction barrels. Drivers first drove the course without texting and then repeated both lab tasks separately while driving through the course again. Throughout the test-track exercise, each participant’s reaction time to a periodic flashing light was recorded.

Reaction times with no texting activity were typically between one and two seconds. Reaction times while texting, however, were at least three to four seconds. Worse yet, drivers were more than 11 times more likely to miss the flashing light altogether when they were texting.

Texas Transportation Institute (TTI) Assistant Research Scientist Joel Cooper directed the study along with TTI colleagues Christine Yager, associate transportation researcher, and Sue Chrysler, manager of TTI’s Human Factors Program. The research involved 42 participants between the ages of 16 and 54 and was funded by the Southwest Region University Transportation Center.

In addition to the reaction-time element, researchers also measured each driver’s ability to maintain proper lane position and a constant speed. Major findings further documented the impairment of texting when compared to the controlled driving conditions. Drivers were less able to:

• safely maintain their position in the driving lane when they were texting, and their swerving was worse in the open sections of the course than in the barreled sections.
• maintain a constant speed while texting, tending to slow down in an effort to reduce the demand of the multiple tasks. By slowing down, a driver gains more time to correct for driving errors (such as the tendency to swerve while texting). Speed variance was also greater for texting drivers than for non-texting drivers.

This work will produce one of the first and only studies in the nation conducted in an actual driving environment. That distinction is important, researchers say, because while simulators are useful, the dynamics of an actual vehicle are different, and some driver cues can’t be replicated in a simulator. By using a closed course, researchers can create an environment similar to real-world driving conditions while providing a high degree of safety for the participants.

“Most research on texting and driving has been limited to driving simulators. This study involved participants driving an actual vehicle,” Yager says. “So one of the more important things we know now that we didn’t know before is that response times are even slower than we previously thought.”

The researchers also examined the productivity level of each driver, measuring the amount of texting activity they could perform while driving. Drivers were generally able to complete about half the exercise content behind the wheel compared to what they could do in the lab setting.

“There’s a general assumption by some people who believe they’re being more productive if they’re exchanging messages while they drive because they’re performing two tasks at once,” Cooper says. “But our findings suggest that the productivity level for each of those tasks drops to less than half what it should be. That indicates to us that texting while driving is not only unsafe, it’s also inefficient.”

The researchers say that another finding from the study dispels a common misconception that composing a text message is a more demanding task than reading one. In post-study interviews, a majority of study participants held that belief, but study results found significant impairment from both reading and writing.

“The findings of this study extend to other distracting activities involving reading and writing, such as checking email or Facebook, while driving,” notes Chrysler.

The total distance covered by each driver in the study was slightly less than 11 miles. In the interest of safety for both participants and the research staff, researchers minimized the complexity of the driving task, using a straight-line course that contained no hills, traffic or potential conflicts other than the construction-zone barrels. Consequently, the driving demands that participants encountered were considerably lower than those they would encounter under real-world conditions.

“It is frightening,” the researchers wrote, “to think of how much more poorly our participants may have performed if the driving conditions were more consistent with routine driving.”

This Issue

Safety Is No Laughing Matter

Volume 47, Number 3
September 2011
Issue Overview

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• For More Information

“Most research on texting and driving has been limited to driving simulators. This study involved participants driving an actual vehicle.”
Christine Yager,
TTI Associate Transportation Researcher

For more information:

Christine Yager
(979) 845-6528
c-yager@ttimail.tamu.edu

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