In-vehicle Tasks Research Articles

A Taxonomy for Secondary In-Vehicle Tasks Based on Eye Glance and Task completion Time

The objective of this research was to develop an initial taxonomy that grouped similar secondary in-vehicle tasks based on driving-related performance measures. This type of taxonomy would be useful to system designers when developing in-vehicle tasks and to researchers. Research was conducted using 2 infotainment systems, 17 tasks, and 89 participants to develop and validate an initial taxonomy. The results indicate that the 17 tasks could be parsed into four distinct groups ranging from selecting an AM band to destination entry. The groupings are based on number of glances and task completion time, which provided the best separation between the groups and consistent results for both static and dynamic testing.

Effects of Ride Motion on the Speed and Accuracy of In-Vehicle Pointing Tasks

Terrain-induced vibration of a moving vehicle adversely affects the ability to quickly and accurately perform in-vehicle pointing tasks by altering the planned fingertip trajectory. The relationship between movement speed and accuracy is a result of the combined use of visual and somatosensory feedbacks which are used to discern movement deviations and make necessary compensatory movements. Participants (N=20) performed three-dimensional rapid pointing tasks under stationary and ride motion conditions to three touchpanel displays. Ride motion contributed to increased reaction and movement times and increased endpoint variability. Trajectory deviations were correlated to the principal direction of vehicle acceleration. Reaches orthogonal to the dominant vehicle acceleration exhibited larger endpoint variability, and reaches to the elevated touchpanel resulted in the largest variability across all motion conditions. Principal axes of endpoint ellipses were along the on-axis and off-axis directions of fingertip movement.

Measuring Distraction: Task Duration and the Lane-Change Test (LCT)

Considerable research activity (e.g., HASTE, CAMP, ADAM projects) is currently focused on producing protocols for assessing the distraction potential of in-vehicle tasks and devices. The Lane Change Test (LCT) is a relatively simple and low cost standardized test scenario designed for measuring driver distraction. The purpose of the present study was to evaluate the LCT's ability to discriminate between different secondary tasks with different levels of workload. The LCT was used to assess the driving performance of twenty-one drivers while they performed typical navigation tasks, Point of Interest (POI) Entry and Destination Entry, each with a low and high workload version. The experimental set up included a steering wheel, foot pedals, monitor, computer and navigation system, all off the shelf. The results indicated that the LCT is a sensitive measure of driver distraction. The participants showed greater mean deviation in lane change path when driving while performing a secondary task (i.e., calibration and navigation tasks) than when driving without performing a secondary task (i.e., baseline). When driving while performing secondary tasks, drivers showed differences in lane change path deviations as a function task type and task complexity. These differences were also reflected in participants mean task time to complete the secondary tasks. The present research provides evidence that the LCT metric of lane change path deviations discriminates between different types and complexity levels of secondary tasks, and that these differences are a function of time taken to complete the secondary tasks.

Intersection Behavior of Novice Teen Drivers and Experienced Adult Drivers

Most unintentional deaths among 16-17 year olds are due to motor vehicle crashes; crash rates for teens are highest for novice teen drivers during the first six months and 1,000 miles after licensure. To date, no on-road research efforts have documented the initial deficits in driving skills for novice teen drivers and improvements with experience. In addition, few efforts have investigated the effects of in-vehicle tasks on driving performance for teens. To address this shortcoming, the performance of novice teen (licensed <1 month) and experienced adult drivers was investigated on a test track. Results for intersection tasks revealed that adults were more likely to stop for an amber light activated at various distances. When performing a cellular phone task while approaching an intersection, adults were more likely to notice and stop for the red light, and teens who did notice the red light were indecisive about how to respond.

Effects of display position of a visual in-vehicle task on simulated driving

To determine the relative safety of onboard display positions while driving, participants performed a lane-keeping task in a driving simulator. Concurrently, they reacted to a light by pushing the brake pedal. A secondary task was projected onto a display at one of the seven different locations in the cockpit. Behavioral data, eye movements, and subjective rating scales showed that the manipulation of display information during driving disturbed drivers’ performance exponentially as a function of distance between the line of sight to the outside primary task and the onboard display position. Vertical eccentricity had a greater detrimental effect than horizontal distance. Under a certain condition with a high secondary task load, reaction time of pushing the brake to the outside stimulus nearly doubled with a diagonal eccentricity of 35° as compared to lower eccentricities. Subjective workload measures complement the behavioral data of clear detrimental effects with eccentricities of at least 35°.

Effects of Voice Technology on Test Track Driving Performance: Implications for Driver Distraction

This work compares the degradation in driving performance associated with secondary tasks performed with voice-based and visual/manual interfaces, including radio tuning, phone dialing, and more complex tasks involving a sequence of interactions with an in-vehicle computer system. Twenty-one participants drove an instrumented vehicle while performing a combination of car-following, peripheral target detection, and secondary tasks on a closed test track. Drivers compensated for increased task demands associated with secondary tasks by increasing their following distance. Performing secondary tasks also resulted in significant decrements to vehicle control, target detection, and car-following performance. The voice-based interface helped reduce the distracting effects of secondary task performance. Modest improvements were observed for measures of vehicle control and target detection but not for car following. The results indicated that performing in-vehicle tasks required diversion of both peripheral (visual and manual) and attentional (cognitive) resources from driving. The voice-based interface reduced the peripheral impairment but did not appreciably reduce the attentional impairment. Actual or potential applications of this research include improvements to the design of invehicle information systems and the development of evaluation protocols to assess their distraction potential.

Sensitivity of eye-movement measures to in-vehicle task difficulty

Abstract Eye-movement measures were found to be highly sensitive to the demands of visual and auditory in-vehicle tasks as well as driving task demands. Two newer measures, Percent road centre and Standard deviation of gaze, were found to be more sensitive, more robust, more reliable, and easier to calculate than established glance-based measures. The eye-movement measures were collected by two partners within the EU project HASTE to determine their sensitivity to increasingly demanding in-vehicle tasks by means of artificial, or surrogate, In-vehicle Information Systems (S-IVIS). Data from 119 subjects were collected from four routes: a motorway in real traffic with an instrumented vehicle, a motorway in a fixed base simulator, and from rural roads in two different fixed base simulators. As the visual task became more difficult, drivers looked less at the road centre area ahead, and looked at the display more often, for longer periods, and for more varied durations. The auditory task led to an increasing gaze concentration to road centre. Gaze concentration to the road centre area was also found as driving task complexity increased, as shown in differences between rural curved- and straight sections, between rural and motorway road types, and between simulator and field motorways.

Methodology for Capturing Driver Eye Glance Behavior During In-Vehicle Secondary Tasks

Driving is a visual task; any driver behavior that takes the driver's visual attention from the driving environment is likely to increase the risk of a crash. Many new intelligent transportation systems telematics applications are now being installed in cars, and some of these may result in substantial degradation of visual attention. Accurately capturing driver eye glance behavior during the evaluation of these devices is critical to assessing the safety impact of engaging in secondary tasks while driving. The development of a methodology is reported; it reliably determines on-road and off-road eye glance duration by using video data collected during highway driving evaluation trials while drivers were engaged with secondary tasks. Human raters determined glance location and duration by detailed coding of the driver's eye movements on the videos. The raters agreed most of the time, but sufficient disagreement suggested that using the consensus of multiple raters significantly improved the reliability of ...

Recovering From Interruptions: Implications for Driver Distraction Research

This research adopted a model of goal activation to study the mechanisms underlying interrupted task performance. The effects of interruption timing, type of interruption, and age on task time and primary task resumption time were explored under conditions in which attention was switched back and forth between two tasks, much as when drivers shift attention between attending to the road and to an in-vehicle task. The timing of interruptions had a significant impact on task resumption times, indicating that the most costly time to interrupt task performance is during the middle of a task. However, this effect was overshadowed by age-related performance decrements for older participants. Interruptions that prevented strategic rehearsal of goals resulted in longer resumption times as compared with interruptions that allowed rehearsal. Actual or potential applications of this research include the design of in-vehicle device user interfaces, the timing of in-vehicle messages, and current metrics for assessing driver distraction.

Focal and Ambient Visual Contributions and Driver Visual Scanning in Lane Keeping and Hazard Detection

In some previous simulator studies, we showed that drivers, engaged in a secondary in-vehicle task at different display separations, were able to buffer some aspects of the driving task (e.g., vehicle control), but not others (e.g., hazard response; Horrey & Wickens, 2002, Horrey, Alexander, & Wickens, 2003). We speculate that this pattern of results may be a result of effective time-sharing between the ambient visual task of vehicle control and the focal visual in-vehicle task, but task interference between the in-vehicle task and the focal task of hazard detection and identification. Alternatively, drivers may be using an optimal scanning strategy that allows them to effectively monitor both the roadway and the in-vehicle device. In this paper, we detail some of the theoretical background, describe some relevant research, and present a model of scanning behavior.

Task interruptability and duration as measures of visual distraction

Tasks that are easily interrupted under intermittent viewing conditions may be less distracting while driving because they allow drivers greater control over task sharing decisions. This paper investigates the reliability and sensitivity of the occlusion paradigm as a potential means of measuring task interruptability and distraction. Twenty-four participants, between the ages of 21 and 34, completed two separate experimental sessions. In one session they performed three in-vehicle tasks (a radio-tuning task and two simulated visual search tasks) under occlusion and while unoccluded. In another session, participants completed the same in-vehicle tasks while driving in a simulator, without occlusion. The tasks did not differ in terms of total task time, yet significant differences were found using the occlusion paradigm and subjective workload ratings. Task interruptability and task duration both need to be considered when assessing the suitability of tasks for time-sharing with driving.

Redundancy, Modality, and Priority in Dual Task Interference

This study examined the effects of several properties of a simulated in-vehicle-task (IVT) on interference with a concurrent tracking task, which simulated vehicle control. We compared auditory, visual and redundant delivery of IVT information, under conditions when the visual display was close and separated from the tracking task. In the first experiment we varied whether the tracking or the IVT was emphasized, and in the second experiment we added instruction in the use of redundant displays. IVT messages varied in length. The results from 20 participants in each experiment revealed (a) an effect of priority on the tracking task only, suggesting that separate resources were used for each task, (b) an advantage for auditory over visual delivery only when the visual display was separated, suggesting that visual costs relate to peripheral, not central resources, (c) no benefit and sometimes noticeable costs for the redundant display, compared to the single modality displays in experiment 1, and (d) an improvement in performance with redundant displays when training was given in experiment 2. The results have a positive bearing on the use of head-up (adjacent) displays for complex information.

Behavioral Adaptation to Adaptive Cruise Control

The ability of adaptive cruise control (ACC) to induce behavioral adaptation in drivers was assessed in a test-track environment. Eighteen experienced drivers performed a secondary, in-vehicle number search task while following a confederate lead vehicle. The three counterbalanced conditions were: No ACC (self-maintained average headway of 2 s), ACC-Short (headway of 1.4 s) and ACC-Long (headway of 2.4 s). Results indicate that ACC can induce behavioral adaptation in potentially safety-critical ways. Participants were able to correctly identify significantly more stock price quotes per minute when using ACC than when they drove unaided. At the same time, participants reacted more slowly to a safety-relevant brake light detection task when they used ACC, and responded within a safe time margin 33% less often. This effect was particularly pronounced in those scoring high on a sensation-seeking scale. ACC use was associated with impaired lane-keeping performance, an effect that was also more evident in high sensation-seekers. During a simulated failure of the ACC system, participants waited until the vehicle-to-vehicle headway was 0.6 s before they intervened; those with an external locus of control took longer to react than those with an internal locus of control. Finally, participants' trust in ACC increased following exposure, and was not affected by the failure of the ACC system. Results are consistent with similar research conducted on lane departure warning systems.

Modeling Steering Using the Queueing Network — Model Human Processor (QN-MHP)

The Queueing Network — Model Human Processor (QN-MHP) is a computational architecture that combines the mathematical theories and simulation methods of queueing networks (QN) with the symbolic and procedure methods of a GOMS-style task description and the Model Human Processor (MHP). Using QN-MHP, a steering model was created to represent the concurrent perceptual, cognitive, and motor activities involved in vehicle steering as truly concurrent processes. The model was compared with driving performance of human subjects and demonstrated realistic steering behavior. It steered a simulated vehicle at a fixed speed within the lane boundaries of straight sections and curves of different radii. In a quantitative validation of several basic measures of driving performance, the steering model yielded steering angle and lateral position similar to the human subject data. This work showed the strength of QN-MHP as a model of driving behavior. Ongoing work further develops the model by expanding the scope of the driving task and by adding a concurrent secondary in-vehicle task.

Driver Distraction: Evaluation with Event Detection Paradigm

The effects of eight in-vehicle tasks on driver distraction were measured in a large, moving-base driving simulator. Forty-eight adults, ranging in age from 35 to 66, and 15 teenagers participated in the simulated drive. Hand-held and hands-free versions of phone dialing, voicemail retrieval, and incoming calls represented six of the eight tasks. Manual radio tuning and climate control adjustment were also included to allow comparison with tasks that have traditionally been present in vehicles. During the drive the participants were asked to respond to sudden movements in surrounding traffic. The driver’s ability to detect these sudden movements or events changed with the nature of the in-vehicle tasks that were being performed. Driving performance measures such as lane violations and heading error were also computed. The performance of the adult group was compared with the performance of the teenage drivers. Compared with the adults, the teens were found to choose unsafe following distances, have poor vehicle control skills, and be more prone to distraction from hand-held phone tasks.

Occlusion Paradigm as a Tool to Assess Visual Distraction from In-Vehicle Telematics

Driver distraction associated with the use of on-board ITS technologies has become an issue of considerable public concern. The ease with which a task can be partitioned, referred to as task chunkability, can likely be a tool to assess the distraction potential of a secondary in-vehicle task to a driver. The present study explored the role of task chunking on distraction. Twenty-four participants, between the ages of 21 and 34, completed two separate experimental sessions. In one session they performed three in-vehicle tasks (a radio-tuning task and two simulated ITS device visual search tasks) under occlusion and while unoccluded. A task chunkability index, a ratio of the mean total shutter open time to the mean unoccluded total task time, was computed for each task. In another session, participants completed the same in-vehicle tasks while driving in a simulator at an approximate speed of 80 km/h, without occlusion. Measures of driving performance (standard deviation of lane position, the number and duration of lane exceedances, and the time to line crossing) under dual task conditions were related to corresponding chunkability indices to determine the association between task chunkability and driving performance. Results indicated that tasks differed significantly in terms of chunkability, however no differences were observed between tasks for the driving performance measures collected. A modified NASA TLX rating scale was also used to assess subjective workload for each task when performed alone and while driving. Significant differences were found between tasks in terms of mental demand, effort, frustration, and safety for both task assessment conditions. Results and implications for future research are discussed.

Individual differences during driver secondary task performance: verbal protocol and visual allocation findings

This paper reports a study in which visual allocation and verbal reports were recorded to determine individual differences in drivers conducting in-vehicle tasks. Participants drove a simulated route whilst conducting pre-defined tasks using the in-vehicle entertainment system. Tasks of varying complexity were presented to the participants. Licensed (experienced) drivers made significantly more verbal reports relating to road signs and markings, vehicles, scenery in general and vehicle operations; than did unlicensed (novices). No significant difference was found between expert and novice drivers when reporting in-car entertainment system related utterances. Surprising gender differences were also found. Males drover faster, with greater variance, and made more utterances in identified categories. Females were found to make significantly less verbal reports during secondary task performance. The difference in results obtained between expert and novices may imply that novices need to use their attention capacity to focus on the skill of driving, whereas experts through experience, have automated this skill and can use their attention capacity to more effectively during primary tasks. Results suggest that expert drivers are not necessarily experts at undertaking secondary tasks.

Primary Task Disruption from Multiple In-Vehicle Systems

In-vehicle systems may distract or interrupt the driver and can compete with the primary task of safe vehicle control. This study investigates the consequences arising from multiple in-vehicle distractions. It aims to investigate the impact of simultaneous information conflicts, from multiple secondary in-vehicle tasks, on the primary task of driving. Participants were presented with a primary task, representing some of the visual and manual aspects of driving, and three secondary tasks (visual, auditory, and visual and auditory stimuli), representing some of the aspects of in-vehicle system operation. Differences between the impact of the three secondary tasks on performance in the primary task were investigated. The priority (high/low) that participants applied to the task was also considered. Lane exceedence (vehicle out of lane) and lane deviation (tracking error) were found to increase with the introduction of secondary tasks. Overall mental workload and anger and frustration were reported as being h...

Primary Task Disruption from Multiple In-Vehicle Systems

In-vehicle systems may distract or interrupt the driver and can compete with the primary task of safe vehicle control. This study investigates the consequences arising from multiple in-vehicle distractions. It aims to investigate the impact of simultaneous information conflicts, from multiple secondary in-vehicle tasks, on the primary task of driving. Participants were presented with a primary task, representing some of the visual and manual aspects of driving, and three secondary tasks (visual, auditory, and visual and auditory stimuli), representing some of the aspects of in-vehicle system operation. Differences between the impact of the three secondary tasks on performance in the primary task were investigated. The priority (high/low) that participants applied to the task was also considered. Lane exceedence (vehicle out of lane) and lane deviation (tracking error) were found to increase with the introduction of secondary tasks. Overall mental workload and anger and frustration were reported as being higher when conducting both primary and secondary tasks, as opposed to solely a primary task. Differences between the impact of the three secondary tasks on these factors were not observed. Findings suggest that in situations of information conflict, participants experience equal task disruption regardless of the sensory channel of the secondary task if the quantity of information presented is carefully controlled. Resource theories would suggest that overloading the visual channel would result in performance decrements. Findings from this study do not support this view.

Development of a Test Protocol to Demonstrate the Effects of Secondary Tasks on Closed-Course Driving Performance

To assess the relative distraction potential associated with a variety of in-vehicle tasks, we developed a test protocol that provides an objective basis for demonstrating the tradeoffs between primary and secondary task performance in driving. The protocol includes two summary scores, one representing driving performance and one representing secondary-task performance. Driving performance was evaluated on a 1.3-mile test course, which included straight and curved road segments, a signalized intersection, a simulated work zone, two changeable-message signs, and six unexpected events. Secondary tasks included mental arithmetic, reading, writing, phone dialing, CD changing, route-guidance destination entry, eating, drinking and grooming. Twelve subjects drove an instrumented vehicle for 9 or 10 timed laps of the test course, each while performing a different secondary task or none (baseline). On average, we found a 15% decrement in driving performance scores on laps in which subjects engaged in a secondary task. Driving performance decrements were observed on 88% of these trials. Differences were observed between different secondary tasks. The pilot test results demonstrate the potential usefulness of the test protocol for assessing tradeoffs between primary and secondary tasks in driving.