Teen Driving Performance Associated with Distraction, ADHD, and Other Risk Factors (2025)
Chapter: Summary
SUMMARY
Teen Driving Performance Associated with Distraction, ADHD, and Other Risk Factors
Background
Fatal crashes involving teen drivers remain a significant concern in transportation safety (Simons-Morton et al., 2015). The primary causes include immaturity, inexperience, and risky behaviors such as speeding, kinematic risky driving (e.g., hard braking or hard cornering), and secondary task engagement (Simons-Morton et al., 2017). Inattention to the roadway resulting from secondary task engagement is a major contributing factor to crash risk for teen drivers. Attention-deficit/hyperactivity disorder (ADHD) also contributes to the excessive risk of crashes among teen drivers. Few studies have examined the impact of inattention on crash risk in teen drivers with ADHD and without ADHD. Naturalistic driving data provide the opportunity to objectively and accurately examine driver inattention to the forward roadway immediately preceding driving events such as crashes/near-crashes (CNCs).
Visual inattention is considered a potential mechanism for ADHD-related deficits (Kingery et al., 2015). Accordingly, eyes-off-road (EOR) metrics are a direct and critical indicator of inattention to the primary task of driving for teens with and without ADHD. Specific eye-glance metrics include the duration and frequency of glances away from the forward roadway. Notably, although previous studies have associated crash risk with EOR, ADHD status, age, and driving experience, few studies have examined the crash risk for the duration of EOR among teen drivers with different ages, levels of experience, and ADHD statuses.
Project Objectives
This research was conducted to examine the CNC risk of various eye-glance durations in teen drivers with different ages, levels of driving experience, and ADHD statuses.
Project Approach
Two datasets from two naturalistic driving studies (NDSs) were used to examine the relationship between eye-glance behavior and crash risk among teen drivers. The second Strategic Highway Research Program (SHRP 2) NDS has provided a unique opportunity to make deductions a priori from collected observational research of secondary tasks performed by young drivers in real time. In this study, teen drivers were recruited without requirements on the timing of licensure, allowing for the inclusion of a broad range of variables such as driver age and ADHD characteristics. The Supervised Practice Driving Study (SPDS) NDS collected both learnerʼs permit driving data and independent driving data from 82 teen
drivers. For this analysis, only the first and second 6-month periods of independent driving were included. For both NDS datasets, the mixed-effect logistic regression model was used with safety outcome (crash or no-crash) as the response variable to examine the effects of driving phase, driver age, ADHD group, and EOR duration. Separate models were fitted for each threshold value of total EOR duration and single longest EOR duration.
Results and Conclusions
This project examined the prevalence of EOR time, as well as the associated CNC risk of looking away from the forward roadway. Both prevalence and risk were assessed for different driving phases and for younger and older teens, as well as those with self-reported ADHD diagnoses. Mixed-effects logistic regression models were employed to calculate odds ratios (ORs), which are accepted estimates of CNC risk.
Overall, the prevalence of EOR during baseline events is lower among teen drivers in the first 6 months and at ages 16 to 17 as compared to the second 6 months and at ages 18 to 19. Although the difference is insignificant, this suggests that teen drivers may be learning and becoming more judicious when looking away from the forward roadway as they progress through the second 6 months. Additionally, the significance of ORs for both age groups and both types of EOR indicates that crash risk and the likelihood of safety-critical events (SCEs) increase with the duration of EOR, which is expected. The increase in risk by duration is highest for single longest EOR. The comparison of EOR crash risk across different driving phases and age groups is consistent with the findings of previous studies (Simons-Morton et al., 2014; Curry et al., 2017; Curry et al., 2019). The total EOR and single longest EOR can be used to estimate the crash risk related to various durations of eye glance. However, they cannot be used to provide the same estimates for the ADHD group. Teen drivers with ADHD had lower prevalence of EOR and lower ORs across four duration thresholds as compared to those without ADHD. The ORs across various duration thresholds in the ADHD groups are not statistically significant. While these results may suggest that EOR may not be associated with heightened crash risk for ADHD teen drivers, it also may suggest that ADHD teen driver glance patterns may be fundamentally different from those of neurotypical teen drivers, as ADHD teens may glance for shorter durations and more frequently. Additional research is needed to explore this hypothesis.
