Timothy Leo Brown

University of Iowa | UI · National Advanced Driving Simulator

The National Advanced Driving Simulator is a high-fidelity motion-base simulator owned by the National Highway Transportation Safety Administration and managed and operated by the University of Iowa. Its 25-year history has intersected with some of the most significant developments in automotive history, such as advanced driver assistance systems l...

Introduction: Cannabis use is a growing concern in transportation and workplace incidents. Because Δ9-tetrahydrocannabinol is detectable after acute psychoactive effects have resolved, it has limitations as an indicator of recent usage or potential impairment. Methods: In an observational study of driving and psychomotor performance, we measured...

Objective The objectives of the current study were to (1) characterize predictors of perceived risk of driving within 2 h of cannabis use and driving after cannabis use in a sample of adults who have used cannabis in the past year and (2) determine whether the influence of these predictors vary by state legalizations status. Methods Data for this...

Driving is a complex neurobehavioural task necessitating the rapid selection, uptake, and processing of visual information. Eye movements that are critical for the execution of visually guided behaviour such as driving are also sensitive to the effects of psychotropic substances. The Embase (via Ovid), EBSCOHost, Psynet, Pubmed, Scopus and Web of S...

Objective: The objective of this analysis was to determine the generalizability of the relationship between different samples of a driver's perceived state after cannabis use and related performance while operating a motor vehicle. Methods: Data were collected from 52 subjects in a study examining the effects of cannabis on driving performance....

Objective: This exploratory study aimed to examine associations between executive function and simulated and self-reported driving behavior among young adults with and without a history of prenatal cocaine exposure (PCE). Methods: Young adult drivers with PCE (n = 38) and with no drug exposure (NDE; n = 25) were recruited from an ongoing longitudin...

The trend toward cannabis legalization in the United States over the past two decades has unsurprisingly been accompanied by an increase in the number of cannabis users and use patterns that potentially pose wider risks to the public like driving under the influence. As such, it is becoming increasingly important to develop methods to accurately qu...

Driving performance measures (DPMs) are important indices for driving and personal safety in vehicle operation. The DPMs are collected under various controlled driving conditions to demonstrate different driving behaviors so that mitigating technology interventions can be studied and designed. However, significant costs are involved in the DPM acqu...

Past research on cannabis has been limited in scope to THC potencies lower than legally available and efforts to integrate the effects into models of driving performance have not been attempted to date. The purpose of this systematic review is to understand the implications for modeling driving performance and describe future research needs. The ri...

Objective Reports indicate that cannabis users will adapt their driving to compensate for the perceived drug effects of cannabis. This analysis examined the relationship between driver perceptions of their state contrasted with objective measures of their performance while operating a motor vehicle. Methods Data was collected from ten subjects in...

Driver monitoring systems (DMS) are the next generation of vehicle safety technology. Broadly, these refer to the embedded, aftermarket wearable or vehicle-mounted devices that collect observable information about the operator to make real-time assessment of their capacity to perform the driving task. Integrating biobehavioral monitoring (primarily...

Objective To examine the relationship between patterns of alcohol use, as determined by the Alcohol Use Disorders Identification Test, and vehicle control measures in high fidelity driving simulation among adult sober drivers. Methods Baseline data (BAC = 0.00%; N = 108) from a larger study aimed at using high-fidelity driving simulation (National...

Objective: To assess divided-attention performance when driving under the influence of cannabis with and without alcohol. Three divided-attention tasks were performed following administration of placebo, cannabis, and/or alcohol. Methods: Healthy adult cannabis users participated in 6 sessions, receiving combinations of cannabis (placebo/low-THC...

Objective: As cannabis use becomes more widely accepted, there is growing interest in its effects on brain function, specifically how it may impact daily functional activities such as driving, operating machinery, and other safety-related tasks. There are currently no validated methods for quantifying impairment from acute cannabis intoxication. T...

Lane departure warnings (LDW) have the potential to mitigate a significant number of lane departure crashes. Such safety benefits have yet been realized, in part due to drivers deactivating LDW systems. Perceived false alarms—where drivers receive a warning but feel the warning was unnecessary or incorrect—could lead to system disuse. In part, this...

Objective Understanding the factors that affect drivers’ response time in takeover from automation can help guide the design of vehicle systems to aid drivers. Higher quantiles of the response time distribution might indicate a higher risk of an unsuccessful takeover. Therefore, assessments of these systems should consider upper quantiles rather th...

Objective: The objective of this study was to use electroencephalogram (EEG) biomarkers derived from a short, easily administered neurocognitive testbed to determine acute cannabis intoxication and its effect on driving performance in a driving simulator. Methods: The data analyzed were from a study examining the relationship between psychomotor ta...

Objective: The objective of this study was to compare the variability in vehicle control for sober young adult drivers (18–23 years old) who either use cannabis but are not acutely exposed or do not use cannabis. Methods: The data analyzed in the study were from 4 prospective driving simulation studies (completed at the National Advanced Driving Si...

The development of automated vehicles continues unabated. The human factor challenges of designing safe automated driving systems are critical as the first several generations of automated vehicles are expected to be semi-autonomous, requiring frequent transfers of control between the driver and vehicle. Conditional automation raises particular con...

Vehicles with SAE Level 2 or 3 automation rely on the driver to intervene and resume control when failures occur. In cases which the driver must steer upon regaining control, the initial conditions of the vehicle’s state variables can affect the success of the drivers' recovery. Hence, a model to determine the consequences of these initial states c...

Drivers’ steering adjustments can be categorized into one-time and chain corrections. One-time corrections lead to no further steering corrections for a minimum of one second, while chain corrections have at least two consecutive steering actions. Chain corrections represent a novel indicator of steering instability. Evolving vehicle dynamics along...

Objective: Alcohol-impaired driving presents a continued risk for traffic safety and results in a significant proportion of fatalities on the roadway. We examined how alcohol at a 0.05% blood alcohol concentration (BAC) compares to 0.10% BAC (above the current U.S. legal limit) in terms of impact on driving performance. Methods: Utilizing a within-...

Objective: Distracted and drug-influenced driving presents a major risk for traffic safety morbidity and mortality. As part of an ongoing research program, we examined the effects of a commonly prescribed combination of medications for pain relief: alprazolam, a benzodiazepine, and a hydrocodone preparation, a combination opiate and acetaminophen,...

This study designs and evaluates a contextual and temporal algorithm for detecting drowsiness-related lane departures. The algorithm uses steering angle, pedal input, vehicle speed and acceleration as input. Speed and acceleration are used to develop a real-time measure of driving context. These measures are integrated with a Dynamic Bayesian Netwo...

Advanced driver assistance systems (ADAS) have the potential to prevent crashes and reduce their severity. Forward collision warnings (FCW) are quickly becoming standard across vehicle lineups and may prevent frontal crashes by alerting drivers. Previous research has demonstrated the effectiveness of FCW for distracted drivers, but their effectiven...

For some individuals with autism spectrum disorder, driving apprehension may interfere with the acquisition and application of driving privileges. The Driving Attitude Scale Parent-Report provides an indication of novice drivers’ positive and negative attitudes toward driving. Responses were compared for parents of 66 autism spectrum disorder and 1...

Lane departures are a significant traffic safety problem. They can be attributed to a variety of types of impairment including the increasing prevalence of distracted driving. Research to date has focused on how drivers respond to imminent lane departure warnings, often with short time to line crossing at the onset of the alert. This paper examines...

Investigate how novice drivers with autism spectrum disorder (ASD) differ from experienced drivers and whether virtual reality driving simulation training (VRDST) improves ASD driving performance. 51 novice ASD drivers (mean age 17.96 years, 78% male) were randomized to routine training (RT) or one of three types of VRDST (8-12 sessions). All parti...

Background Operating farm tractors is dangerous for children. Recent studies document mismatches between children and physical requirements for operating tractors. The role of cognition has not been studied, because such research conducted in real-life situations places youth at risk. The objective of this study was to evaluate the feasibility and...

Objective Driver drowsiness contributes to a substantial number of fatal and non-fatal crashes, with recent estimates attributing up to 21% of fatal crashes to drowsiness. This paper describes recent NHTSA research on in-vehicle drowsiness countermeasures. Recent advances in technology and state detection algorithms have shown success in detecting...

Although evidence suggests cannabis impairs driving, its driving-performance effects are not fully characterized. We aimed to establish cannabis’ effects on driving longitudinal control (with and without alcohol, drivers’ most common drug combination) relative to psychoactive ∆⁹-tetrahydrocannabinol (THC) blood concentrations. Current occasional (≥...

Background: Impairments related to autism spectrum disorders (ASDs) can pose limits on daily living skills. One example relates to driving, which allows autonomy and permits maintenance of social- and work-related contacts. Research regarding ASD and driving has been steadily increasing in the past years. Most studies however focus on difficulties...

Oral fluid (OF) is an advantageous matrix for cannabis detection, with on-site tests available for roadside drug-impaired driver screening. Limited data exist for device performance following consumption of vaporized cannabis, which reduces exposure to harmful combustion by-products. We assessed cannabinoid OF disposition, with and without alcohol,...

Background: In driving-under-the-influence cases, blood typically is collected approximately 1.5-4 h after an incident, with unknown last intake time. This complicates blood Δ(9)-tetrahydrocannabinol (THC) interpretation, owing to rapidly decreasing concentrations immediately after inhalation. We evaluated how decreases in blood THC concentration...

Impaired driving due to drug use is a growing problem worldwide; estimates show that 18–23.5% of fatal accidents, and up to 34% of injury accidents may be caused by drivers under the influence of drugs (Drummer et al., 2003; Walsh et al., 2004; NHTSA, 2010). Furthermore, at any given time, up to 16% of drivers may be using drugs that can impair one...

Rear-end collisions account for a high percentage of crashes and are largely attributable to driver inattention. Advanced crash warning systems offer the potential to mitigate such crashes by alerting the driver, reorienting attention, and speeding response time. Developing an understanding whether warning timing influences the effectiveness of dif...

Vaporized cannabis and concurrent cannabis and alcohol intake are commonplace. We evaluated the subjective effects of cannabis, with and without alcohol, relative to blood and oral fluid (OF, advantageous for cannabis exposure screening) cannabinoid concentrations and OF/blood and OF/plasma vaporized-cannabinoid relationships. Healthy adult occasio...

The pilot study presented herein aims to extend Parkinson's research involving event-related EEG features, proposing a new portable platform for simultaneous cognitive assessment and ERP paradigms: the Mobile Alertness and Memory Profiler (mAMP). The preliminary results establish feasibility within the patient population of concern.

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This research paper explores how different drug mechanisms within a single class of drugs can produce different profiles of driving impairment. Prior research has failed to consider these mechanistic differences and often utilizes less controlled study methodologies. The potential impact of differing mechanistic effects is important for practitione...

The discussion about the effects and subsequent safety of cannabis generates enormous controversy during this period when medical and government agencies determine decriminalization and/or legalization of (medical) cannabis. Scientific data concerning the pharmacology and pharmcodynamics of the drug remain incomplete for many reasons. Therefore it...

Abstract BACKGROUND: Increased medical and legal cannabis intake is accompanied by greater use of cannabis vaporization and more cases of driving under the influence of cannabis. Although simultaneous Δ9-tetrahydrocannabinol (THC) and alcohol use is frequent, potential pharmacokinetic interactions are poorly understood. Here we studied blood and p...

Increased medical and legal cannabis intake is accompanied by greater use of cannabis vaporization and more cases of driving under the influence of cannabis. Although simultaneous Δ(9)-tetrahydrocannabinol (THC) and alcohol use is frequent, potential pharmacokinetic interactions are poorly understood. Here we studied blood and plasma vaporized cann...

A growing body of evidence suggests that EEG analyses, including both resting state and event-related stimulation protocols, may be useful in both early detection of neural signatures of dementia, as well as in discriminating between the sub-types of dementia – like the Lewy Body Dementias, such as Parkinson's Disease (PD) and Parkinson's with Deme...

Development of a standardized driving simulation protocol to assess impairment by drugs Use of a validated driving simulation protocol offers a unique opportunity to test impairing effects of CNS active therapeutic agents in a safe, reproducible, and customizable environment. Currently there is no standardized method to test drugs that may impair...

Objective: The aim of this study was to design and evaluate an algorithm for detecting drowsiness-related lane departures by applying a random forest classifier to steering wheel angle data. Background: Although algorithms exist to detect and mitigate driver drowsiness, the high rate of false alarms and missed detection of drowsiness represent p...

This workshop will focus on transportation and mobility for working age adults with one or more of the following: Post Traumatic Stress Disorder (PTSD), Anxiety Disorders, Autism Spectrum Disorder (ASD) and Cognitive Impairments. The session will benefit transportation providers serving these populations as well as policymakers looking to better un...

Drowsy driving is a significant contributor to death and injury crashes on our Nation's highways, accounting for more than 80,000 crashes and 850 fatalities per year. The successful detection of drowsiness is a crucial step in implementing mitigation strategies to reduce the cost to society of drowsy driving. Building upon prior research in detecti...

Impaired driving is a significant traffic safety problem, and alcohol and drugs taken before driving contribute substantially to this problem. With the increase in use of prescription medication and the decriminalization of some drugs, it has become increasingly important to understand the manifestation of driver impairment. Building upon previous...

Drowsy driving is a significant contributor to death and injury crashes on our nation's highways. Predictive neurophysiologic/physiologic solutions to reduce these incidences have been proposed and developed. EEG based metrics were found to be promising in initial studies, but remain controversial in their efficacy, primarily due to failures to dev...

It is widely known that young drivers are over-represented in the crash data for reasons such as risk perception and acceptance, age, gender, experience, exposure, and social contexts. The current mitigations implemented to address this issue consist mainly of graduated driver’s licenses and parental involvement programs. However, as technology beg...

Drowsy driving is a significant factor in many motor vehicle crashes in the United States and across the world. Efforts to reduce these crashes have developed numerous algorithms to detect both acute and chronic drowsiness. These algorithms employ behavioral and physiological data, and have used different machine learning techniques. This work prop...

The objective of this study was to investigate use patterns among early adopters of adaptive cruise control (ACC). Extended use ofACC may influence a driver's behavior in the long-term, which can have unintended safety consequences. The authors examined the use of a motion-based simulator by 24 participants (15 males and 9 females). Cluster analysi...

This article reviews the advantages of performing driving research in a high-fidelity driving simulator where the driver can be challenged in ways that could lead to property damage and personal injury if done on a test track or public roadway. Several vision related studies performed at the University of Iowa National Advanced Driving Simulator ar...