Distraction ‘Hangover’: Characterization of the Delayed Return to Baseline Driving Risk After Distracting Behaviors

Research Team: Linda L. Hill (lead), Jeanne Townsend, Joseph Snider, Ryan Spence, Anne-Marie Engler, Ryan Moran, Sarah Hacker, and Leanne Chukoskie

UC Campus(es): 

Additional Research Partners: UC San Diego

Problem Statement: In 2015, 3,477 people were killed and about 391,000 were injured due to distracted driving in the U.S.; this accounts for 6.7% of all fatal crashes that year. Distracted driving can take many forms, including talking or texting on a cell phone. Research overwhelmingly supports a detrimental relationship between distracted driving and crash risk. While this relationship clearly occurs during the acts of distraction, there is preliminary evidence that the elevated crash risk continues for some time after the distracted acts are over, whether by hands-held or hands-free. In California, the cell phone laws as of January 2017, prohibit any type of manipulation of cell phones while driving, with no cell phone use allowed (handsfree or handheld) in drivers less than 18 or bus drivers. However, despite distraction being implicated in 80% of crashes according to the California Office of Traffic Safety, there are no restrictions to hands-free use in other groups.

Project Description: This project measured the effects of handsfree 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 following task dropped from 0.54 to 0.045 during distraction, and seven participants rear-ended the lead car.

Status: Completed

Budget: $79,999

Policy Brief(s):