Caroline Crump

Heart rate variability and treatment outcome in major depression: a pilot study.

Variations in heart rate variability (HRV) have been associated with major depressive disorder (MDD), but the relationship of baseline HRV to treatment outcome in MDD is unclear. We conducted a pilot study to examine associations between resting baseline HRV and MDD treatment outcome. We retrospectively tested several parameters of HRV in an MDD treatment study with escitalopram (ESC, N=26) to generate a model of how baseline HRV related to treatment outcome, and cross-validated the model in a separate trial of MDD treatment with Iyengar yoga (IY, N=16). Lower relative power of very low frequency (rVLF) HRV at baseline predicted improvement in depressive symptoms when adjusted for age and gender (R2>.43 and p<0.05 for both trials). Although vagal parasympathetic measures were correlated with antidepressant treatment outcome, their predictive power was not significant after adjusting for age and gender. In conclusion, baseline resting rVLF was associated with depression treatment outcome in two independent MDD treatment studies. These results should be interpreted with caution due to limited sample size, but a strength of this study is its validation of the rVLF predictor in an independent sample. rVLF merits prospective confirmation as a candidate biomarker.

Driver Distraction and Advanced Vehicle Assistive Systems (ADAS): Investigating Effects on Driver Behavior

The component technologies of Advanced Driver Assistive Systems (ADAS) are becoming increasingly automated, with systems capable of operating in concert in multiple driving environments. However, how these systems affect a driver’s ability to safely, efficiently, and comfortably operate a vehicle remains unclear. We investigated the effects of ADAS [specifically Lane Departure Warning (LDW)] on driving performance while participants performed a secondary task (mental math) designed to simulate cognitive effort while driving. The experiment was conducted on a closed-course test track in an instrumented vehicle. Results suggest that cognitive engagement influenced driver control of the vehicle. Effects of cognitive engagement in a secondary task were not mitigated by the presence of LDW. We discuss our results in the framework of a continued need for active input and control from the human operator in vehicles with assistive technologies.

Differing Perceptions of Advanced Driver Assistance Systems (ADAS)

The extent to which drivers’ attitudes toward the use of autonomous vehicle systems can be influenced by various driver factors (e.g., driver age, experience with the systems, etc.) has yet to be firmly established. To investigate driver perceptions and acceptance of advanced vehicle systems, the current research examined initial and repeated exposure to systems while driving under various commonly encountered on-road situations (e.g., emergency braking). Somewhat surprisingly, driver perceptions of safety when driving vehicles with assistive technologies diminished following repeated exposure to the technologies. However, when drivers were afforded more extensive experience, they reported a heightened appreciation of the systems—especially drivers who might benefit most from this assistance (e.g., distracted or older drivers).

Eye Tracking Evaluation of Driver Visual Behavior with a Forward Collision Warning and Mitigation System

As Advanced Driver Assistance Systems (ADAS) technologies become more commonplace and monitor an increasing number of aspects of the visual environment for drivers, typical driver visual behavior is likely to shift accordingly. Research on drivers’ responses to vehicles equipped with different ADAS technologies is required to evaluate how these systems influence driver visual behavior. The current study analyzed eye tracking metrics collected as part of a larger test track evaluation of drivers’ responses to a simulated emergency lead vehicle braking event while driving a vehicle equipped with a forward collision warning and mitigation (FCWM) system. In the experiment, driver behavior was examined both with and without concurrent performance of a secondary arithmetic task conducted on a hands-free cell phone. We found that participants experienced a startle response (as indicated by pupil dilation) at the time of the emergency event, which indicates the event was an effectively surprising experimental manipulation. We also found that participants predominantly fixated the lead vehicle, although participants performing the secondary task fixated the lead vehicle less often. All participants fixated the head-up display (HUD) rarely and briefly. However, older drivers spent more time fixating the HUD than younger drivers.

Consumer perceptions, understanding, and expectations of Advanced Driver Assistance Systems (ADAS) and vehicle automation

Consumers are faced with an increasingly complex decision process as novel safety technologies become commonplace in new vehicles. Consumers’ knowledge of these systems is potentially limited given the recent introduction and constant evolution of ADAS. We examined consumers’ understanding and perceptions of ADAS and vehicle automation in a national survey. Our analysis focused on consumers’ understanding of how certain driving tasks that can be automated (e.g., steering, braking, navigation, etc.) maps onto proposed levels of vehicle automation. Additionally, we report what sources of information and methods of education consumers prefer to utilize when learning about new safety systems. These data can inform new driver training, public policy and transportation goals of how best to educate the motoring public about new vehicle technologies and the capabilities of next-generation automated vehicles as well as facilitate public acceptance of higher levels of vehicle automation.

Passenger Seat Belt Usage Rates on Shuttle Buses

The National Highway Traffic Safety Administration (NHTSA) recently published a final rule requiring lap/shoulder seat belts in all new large motorcoaches and buses manufactured on or after November 28, 2016 (NHTSA, 2013). Studies of vehicle belt use in passenger vehicles demonstrate that many factors other than availability influence whether a seat belt is used by an individual in a particular circumstance. The present observational study examined passenger seat belt use in airport shuttle buses traveling short distances over urban roads with frequent stops, in four U.S. cities. Seat belts were used very rarely when provided - only 1% (2 out of 156) of passengers buckled up. These findings are consistent with other studies of passenger seat belt use in motorcoach buses, and suggest that without concomitant legislation mandating and enforcing seat belt usage, the vast majority of bus passengers are unlikely to use seat belts even when provided.