Do you think using a hands-free device makes it okay to talk on a cell phone while driving? Despite the well-intended laws requiring the use of hands-free devices, a driver's performance is impaired when distracted by even the simplest tasks, whether or not both hands are on the steering wheel.
Until now, the slowing of reaction time under multitasking conditions, referred to as the psychological-refractory-period (PRP) effect, has been studied mainly with simple tasks in laboratory settings. But a new research study presents a unique perspective of how the PRP effect pertains to driving, perhaps the most ubiquitous real-world task where non-optimal performance can have serious consequences.
The study was conducted by University of California, San Diego scientists Jonathan Levy and Harold Pashler, along with Erwin Boer of ERB Consulting. Their research appears in the article "Central Interference in Driving: Is There Any Stopping the Psychological Refractory Period?" in the March issue of Psychological Science.
Forty students participated in the study, which involved driving a car simulator, composed of a large plasma screen, a steering wheel, and gas and brake pedals located on the floor. In the simulation, students followed a lead car and were instructed to brake as soon as they saw the illumination of the lead car's brake lights (they were instructed to avoid gradual slowing even if it was possible). While subjects performed the braking task, they occasionally were required to respond to a concurrent easy task, where a stimulus - either a light flash in the lead car's rear window or an auditory tone - was randomly presented once or twice. Participants indicated the stimulus' frequency, sometimes by pressing a key on the steering wheel once or twice and sometimes by saying aloud the words "one" or "two."