Texting, or emailing, while driving doubles reaction time and makes drivers more likely to miss a flashing light, according to new research.
In a small study researchers at Texas A&M University's Texas Transportation Institute studied the impact of texting in an actual driving environment.
"Essentially texting while driving doubles a driver's reaction time," said Christine Yager, who led the study. "That makes a driver less able to respond to sudden roadway dangers,"
In the study 42 drivers between the ages of 16 and 54 drove on an 11-mile (17 km) test course while sending or receiving text messages, and again while focusing completely on the road.
The researchers asked the drivers to stop when they saw a flashing yellow light and recorded their reaction time.
The typical reaction time without texting was between one and two seconds, but while texting it increased to three to four seconds, regardless of whether the driver was typing or reading a text.
The researchers also found that a texting driver was 11 times more likely to miss the flashing light.
"The act of reading and writing a text message are equally impairing and equally dangerous," she said.
The lag in reaction times was greater than in an earlier study conducted in a lab simulator. Yager explained that the three to four second lag time is significant because at highway speeds a driver can travel the length of a football field in that time.
Texting drivers in the study were also more likely to swerve in their lane.
"We had participants strike barrels, and it is very scary to think that this is happening on our public roadways," said Yager, adding the findings also apply to other distractions such as checking emails and Facebook.
Government statistics show distracted driving contributes to as much as 20 percent of all fatal crashes. Cell phones are the main distraction.
Text messaging while driving is banned in 34 U.S. states and the District of Columbia, according to the Insurance Institute for Highway Safety. An additional seven states ban texting while driving for some motorists, such as those under 18 or bus drivers.