The TTI study used an 11-mile-long test course and selected 42 participants ranging in age from 16 through 54. Subjects were told to drive the course while sending and receiving text messages, and then to repeat the course while focusing exclusively on the road ahead.
Drivers were advised to stop when they saw a flashing yellow light, and reactions times were logged both with and without texting.
The results are a bit horrifying. First, reading a text or writing a text makes no difference on the level of impairment, and both actions doubled a driver’s reaction time. Drivers paying attention generally had reaction times ranging from one to two seconds, while text-impaired drivers had reaction times of three to four seconds.
In case that’s not bad enough, text-impaired drivers were 11 times more likely to miss the flashing light, and were also more inclined to swerve within their lanes.
An earlier study showed a lower level of impairment, but it was conducted in a computer simulator. The recent TTI study had participants driving a closed course in actual vehicles, which is more representative of a real-world environment.
Still not convinced? Ponder this: a two second delay in reaction time, at fifty miles per hour, translates into an increase of roughly 148 feet in stopping distance.