In fact, the risk is nearly identical, with both ways cutting reaction time for drivers in half.
Christine Yager, who led the study for the Texas A&M Transportation Institute, said the research was "a useful step, and we’re eager to see what other studies may find."
It was conducted as part of National Distracted Driving Awareness Month.
A number of unsettling statistics have come out recently as part of the ongoing effort to help reduce behavior called “distracted driving.”
In March, a study found that adults are far more likely to text while driving than teens. Another study released in early April found that daydreaming while driving results in thousands of fatal car accidents each year.
For its study, TTI tested 47 drivers on a closed course to measure their reaction times while using the two most popular voice-controlled texting apps, Siri and Vlingo.
The drivers went around the course three times: once while not using their phone; once texting with their hands; and once texting by voice. A stoplight appeared at random intervals, and the researchers compared how long it took the drivers to respond.
“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,” an excerpt from the study reads.
The study had some other interesting findings. Drivers reported, for instance, that they felt safer when texting by voice compared with their hands. And it found that the latter was slightly faster than texting by voice, along with posing the same general amount of risk.
The study did not specify why texting by voice posed the same risk. But several factors could explain the results, including the fact that an individual must still look at the phone to read and send his or her text message, even if using a "hands-free" device.