This US simulator study was conducted to measure the cognitive distraction of voice-based technologies in the vehicle. Participants (N=45) ranged in age from 18 to 40 years with an average age of 24.9. The simulator experiments was designed to evaluate nine voice-based technologies, including using “hands-free” Siri to listen to and send text messages, interacting with a menu-based system, and listening and composing e-mail and text replies read by a synthetic or natural voice. While using the simulator the nine voice-based technologies were used by drivers to send texts and e-mails.
Results showed that the task of selecting and listening to the audio messages contributed approximately 55% to the increased cognitive workload. Furthermore, as the cognitive workload associated with performing secondary tasks increased, the cognitive distraction associated with performing that activity while driving should increase. Overall, results suggested that voice-based interactions within the vehicle may have unintended negative consequences that affect traffic safety.
Strayer, D. L., Turrill, J., Coleman, J. R., Ortiz, E. V., & Cooper, J. M. (2014). Measuring Cognitive Distraction in the Automobile II: Assessing In-Vehicle Voice-Based. Accident Analysis & Prevention, 372, 379.