The researchers used cameras to track the driver's eye and head movement, a Detection-Response-Task device known as the "DRT" to record driver reaction time, and a electroencephalograph (EEG)-configured skull cap to chart drivers' brain activity too determine mental workload.
A driver undergoes a cognitive response test at the University of Utah.
Drivers participating in the study engaged in common tasks, ranging from listening to an audio book or talking on the phone to listening and responding to voice-activated emails while behind the wheel.
The levels of mental distraction were represented on a scale of one to three, one being the least and three being the most.
Tasks such as listening to the radio ranked as a category one level of distraction or a minimal risk, while talking on a cell phone, both handheld and hands-free, resulted in a category two (moderate) level of distraction.
The highest level of distraction was attributed to listening and responding to in-vehicle, voice-activated email features, which increased mental workload and distraction levels of the drivers to the point of "extensive risk."
"These findings reinforce previous research that hands-free is not risk-free," AAA Foundation CEO Peter Kissinger said in a statement. "Increased mental workload and cognitive distractions can lead to a type of tunnel vision or inattention blindness where motorists don't see potential hazards right in front of them."
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