Abstract
Drivers know that smartphones distract them. Trying to limit distraction, drivers can use hands-free devices, where they only briefly glance at the smartphone. However, the cognitive cost of switching tasks from driving to communicating back to driving adds an underappreciated, potentially long period to the total distraction time. This project measured the effect of hands-free smartphones on driving behaviors by engaging ninety-seven 21- to 78-year-old individuals who self-identified as active drivers and smartphone users in a simulated driving scenario that included smartphone distractions. Peripheral cue and car-following tasks were used to assess driving behavior, along with synchronized eye-tracking. This research found that simulated driving performance drops to dangerous levels after smartphone distraction for all ages and for both voice and texting. The participants swerved for 15.1 seconds after a voice distraction and for a longer 20.6 seconds after a text distraction. Participants from the 71+ age group missed seeing about 50% of peripheral cues within 4 seconds of the distraction. Coherence with the lead car during the following task dropped from 0.54 to 0.045 during the distraction, and seven participants rear-ended the lead car.