Fatal crash between a car operating with automated control systems and a tractor-semitrailer truck.

OBJECTIVE: The objective of this investigation was to evaluate the interaction between an SAE level 2 automated vehicle and the driver, including the limitations imposed by the vehicle on the driver. METHODS: A case study of the first fatal crash involving a vehicle operating with an automated control system was performed using scene evidence, vehicle damage, and recorded data available from the vehicle, and information from both drivers, including experience, phone records, computer systems, and medical information, was reviewed. RESULTS: System performance data downloaded from the car indicated that the driver was operating it using the Traffic-Aware Cruise Control and Autosteer lane-keeping systems, which are automated vehicle control systems within Tesla's Autopilot suite. As the car crested the hill, a tractor trailer began its left turn onto a crossing roadway. Although reconstruction of the crash determined that there was sufficient sight distance for both drivers to see each other and take action, neither responded to the circumstances leading to the collision. Further, based on the speeds of the vehicles and simulations of the truck's path, the car driver had at least 10.4 s to detect the truck and take evasive action. Neither the car driver nor the Autopilot system changed the vehicle's velocity. At the time of the crash, the system performance data indicated that the last driver interaction with the system was 1 min 51 s prior when the cruise control speed was set to 74 mph. The driver was operating the vehicle using the Autopilot system for 37 of the 41 min in the last trip. During this period, the vehicle detected the driver's hands on the steering wheel for a total of 25 s; each time his hands were detected on the wheel was preceded by a visual alert or auditory warning. CONCLUSIONS: The National Transportation Safety Board (NTSB) determined that the probable cause of the Williston, Florida, crash was the truck driver's failure to yield the right of way to the car, combined with the car driver's inattention due to overreliance on vehicle automation, which resulted in the car driver's lack of reaction to the presence of the truck. Contributing to the car driver's overreliance on the vehicle automation was the car's operational design, which permitted the driver's prolonged disengagement from the driving task and his use of the automation in ways inconsistent with guidance and warnings from the manufacturer.

Factors associated with civilian drivers involved in crashes with emergency vehicles.

Motor vehicle crashes involving civilian and emergency vehicles (EVs) have been a known problem that contributes to fatal and nonfatal injuries; however, characteristics associated with civilian drivers have not been examined adequately. This study used data from The National Highway Traffic Safety Administration's Fatality Analysis Reporting System and the National Automotive Sampling System General Estimates System to identify driver, roadway, environmental, and crash factors, and consequences for civilian drivers involved in fatal and nonfatal crashes with in-use and in-transport EVs. In general, drivers involved in emergency-civilian crashes (ECCs) were more often driving: straight through intersections (vs. same direction) of four-points or more (vs. not at intersection); where traffic signals were present (vs. no traffic control device); and at night (vs. midday). For nonfatal ECCs, drivers were more often driving: distracted (vs. not distracted); with vision obstructed by external objects (vs. no obstruction); on dark but lighted roads (vs. daylight); and in opposite directions (vs. same directions) of the EVs. Consequences included increased risk of injury (vs. no injury) and receiving traffic violations (vs. no violation). Fatal ECCs were associated with driving on urban roads (vs. rural), although these types of crashes were less likely to occur on dark roads (vs. daylight). The findings of this study suggest drivers may have difficulties in visually detecting EVs in different environments.

Aging and the impact of distraction on an intersection crossing assist system.

It is known that distraction reduces the benefits of collision avoidance systems by slowing a driver's response. The current study examined the impact of a drivers' use of an in-vehicle intersection crossing assist system under demanding cognitive load conditions. Forty eight drivers crossed a busy rural intersection in a simulated environment while completing four blocks of trials, in half of which they used the assist system and engaged in a working memory task. Participants were dichotomized into older and younger age groups. The results showed a tendency towards conservative driving in a single-task condition when only using the assist system. A similar shift in driving style was observed when drivers crossed the intersection while engaged in a secondary task. Using the in-vehicle intersection crossing assist system under cognitively demanding conditions did not result in adverse consequences-the impact of distraction was different compared to a typical collision avoidance system. Older drivers showed some evidence of more conservative intersection crossing, however they also appeared to rely more on the in-vehicle assist system when presented with an extraneous additional task.

Mind wandering behind the wheel: performance and oculomotor correlates.

OBJECTIVE: An experiment studied the frequency and correlates of driver mind wandering. BACKGROUND: Driver mind wandering is associated with risk for crash involvement. The present experiment examined the performance and attentional changes by which this effect might occur. METHOD: Participants performed a car-following task in a high-fidelity driving simulator and were asked to report any time they caught themselves mind wandering. Vehicle control and eye movement data were recorded. RESULTS: As compared with their attentive performance, participants showed few deficits in vehicle control while mind wandering but tended to focus visual attention narrowly on the road ahead. CONCLUSION: Data suggest that mind wandering can engender a failure to monitor the environment while driving. APPLICATION: Results identify behavioral correlates and potential risks of mind wandering that might enable efforts to detect and mitigate driver inattention.

Driving impairs talking.

It is well known that conversation (e.g., on a cell phone) impairs driving. We demonstrate that the reverse is also true: Language production and comprehension, and the encoding of the products of comprehension into memory, are less accurate when one is driving. Ninety-six pairs of drivers and conversation partners engaged in a story-retelling task in a driving simulator. Half of the pairs were older adults. Each pair completed one dual-task block (driving during the retelling task) and two single-task control blocks. The results showed a decline in the accuracy of the drivers' storytelling and of their memory for stories that were told to them by their nondriving partners. Speech production suffered an additional cost when the difficulty of driving increased. Measures of driving performance suggested that the drivers gave priority to the driving task when they were conversing. As a result, their linguistic performance suffered.

Stable individual differences in search strategy? The effect of task demands and motivational factors on scanning strategy in visual search.

Previous studies have demonstrated large individual differences in scanning strategy during a dynamic visual search task (E. Becic, A. F. Kramer, & W. R. Boot, 2007; W. R. Boot, A. F. Kramer, E. Becic, D. A. Wiegmann, & T. Kubose, 2006). These differences accounted for substantial variance in performance. Participants who chose to search covertly (without eye movements) excelled, participants who searched overtly (with eye movements) performed poorly. The aim of the current study was to investigate the stability of scanning strategies across different visual search tasks in an attempt to explain why a large percentage of observers might engage in maladaptive strategies. Scanning strategy was assessed for a group of observers across a variety of search tasks without feedback (efficient search, inefficient search, change detection, dynamic search). While scanning strategy was partly determined by task demands, stable individual differences emerged. Participants who searched either overtly or covertly tended to adopt the same strategy regardless of the demands of the search task, even in tasks in which such a strategy was maladaptive. However, when participants were given explicit feedback about their performance during search and performance incentives, strategies across tasks diverged. Thus it appears that observers by default will favor a particular search strategy but can modify this strategy when it is clearly maladaptive to the task.

Transfer effects in task-set cost and dual-task cost after dual-task training in older and younger adults: further evidence for cognitive plasticity in attentional control in late adulthood.

Older adults' difficulties in performing two tasks concurrently have been well documented (Kramer & Madden, 2008). It has been observed that the age-related differences in dual-task performance are larger when the two tasks require similar motor responses (2001) and that in some conditions older adults also show greater susceptibility than younger adults to input interference (Hein & Schubert, 2004). The authors recently observed that even when the two tasks require motor responses, both older and younger adults can learn to perform a visual discrimination task and an auditory discrimination task faster and more accurately (Bherer et al., 2005). In the present study, the authors extended this finding to a dual-task condition that involves two visual tasks requiring two motor responses. Older and younger adults completed a dual-task training program in which continuous individualized adaptive feedback was provided to enhance performance. The results indicate that, even with similar motor responses and two visual stimuli, both older and younger adults showed substantial gains in performance after training and that the improvement generalized to new task combinations involving new stimuli. These results suggest that dual-task skills can be substantially improved in older adults and that cognitive plasticity in attentional control is still possible in old age.

Training older adults to search more effectively: scanning strategy and visual search in dynamic displays.

The authors examined the ability of older adults to modify their search strategies to detect changes in dynamic displays. Older adults who made few eye movements during search (i.e., covert searchers) were faster and more accurate compared with individuals who made many eye movements (i.e., overt searchers). When overt searchers were instructed to adopt a covert search strategy, target detection performance increased to the level of natural covert searchers. Similarly, covert searchers instructed to search overtly exhibited a decrease in target detection performance. These data suggest that with instructions and minimal practice, older adults can ameliorate the cost of a poor search strategy.

Temporal limitations in multiple target detection in a dynamic monitoring task.

OBJECTIVE: Two experiments examined the detectability of multiple transient changes within a cluttered and dynamic display (a simulated sonar display). BACKGROUND: Research suggests that there are severe limitations when multiple targets must be detected within close temporal proximity. The present research explored whether these limitations influence performance in a dynamic monitoring task. METHOD: Participants monitored a cluttered and dynamic display and reported the number of new objects that appeared (one to four objects). The time between onset events was varied. A blinking cue sometimes accompanied each new object, giving observers multiple opportunities to detect it. RESULTS: A large decrease in performance was observed when participants were asked to detect multiple targets within a short period of time. Performance was worse than predicted based on the attention literature. Performance suffered when observers were asked to detect more than two or three targets. The blinking cue greatly attenuated this performance deficit, even for short-duration blinking cues (one blink). CONCLUSION: Operators can easily become overwhelmed when asked to respond to even a small number of events when these events occur close in time. Extending transient events in time improves performance, but some attentional limitations may be difficult or impossible to overcome. APPLICATION: These results have important implications for systems in which important events may occur within close temporal proximity (e.g., when a sonar operator is tasked with detecting threats in the battle space). Situations in which these limitations may or may not influence performance are discussed.

Influence of age and proximity warning devices on collision avoidance in simulated driving.

OBJECTIVE: We conducted a set of experiments to examine the utility of several different uni- and multimodal collision avoidance systems (CASs) on driving performance of young and older adult drivers in a high-fidelity simulator. BACKGROUND: Although previous research has examined the efficacy of different CASs on collision avoidance, there has been a dearth of studies that have examined such devices in different driving situations with different populations of drivers. METHOD: Several different CAS warnings were examined in varying traffic and collision configurations both without (Experiment 1a) and with (Experiment 2) a distracting in-vehicle task. RESULTS: Overall, collision avoidance performance for both potential forward and side object collisions was best for an auditory/visual CAS, which alerted drivers using both modalities. Interestingly, older drivers (60-82 years of age) benefited as much as younger drivers from the CAS, and sometimes they benefited more. CONCLUSION: These data suggest that CASs can be beneficial across a number of different driving scenarios, types of collisions, and driver populations. APPLICATION: These results have important implications for the design and implementation of CASs for different driver populations and driving conditions.

Age-related differences in visual search in dynamic displays.

The authors examined the ability of younger and older adults to detect changes in dynamic displays. Older and younger adults viewed displays containing numerous moving objects and were asked to respond when a new object was added to the display. Accuracy, response times, and eye movements were recorded. For both younger and older participants, the number of eye movements accounted for a large proportion of variance in transient detection performance. Participants who actively searched for the change performed significantly worse than did participants who employed a passive or covert scan strategy, indicating that passive scanning may be a beneficial strategy in certain dynamic environments. The cost of an active scan strategy was especially high for older participants in terms of both accuracy and response times. However, older adults who employed a passive or covert scan strategy showed greater improvement, relative to older active searchers, than did younger adults. These results highlight the importance of individual differences in scanning strategy in real-world dynamic, cluttered environments.

Age-related differences in the use of background layout in visual search.

The effect of background layout on visual search performance, and more specifically on the tendency to refixate previously inspected locations and objects, was investigated. Older and younger adults performed a search task in which a background layout or landmark was present or absent in a gaze contingent visual search paradigm. Regardless of age, participants demonstrated fewer refixations when landmarks were present, with older adults showing a larger landmark advantage. This visual search advantage did not come at the cost of saccadic latency. Furthermore, the visual search performance advantage obtained in the presence of a background layout or landmark was observed both for individuals with small and large memory spans.

Testing the limits of cognitive plasticity in older adults: application to attentional control.

Laboratory based training studies suggest that older adults can benefit from training in tasks that tap control aspects of attention. This was further explored in the present study in which older and younger adults completed an adaptive and individualized dual-task training program. The testing-the-limits approach was used [Lindenberger, U., & Baltes, P. B. (1995). Testing-the-limits and experimental simulation: Two methods to explicate the role of learning in development. Human Development, 38, 349-360.] in order to gain insight into how attentional control can be improved in older adults. Results indicated substantial improvement in overlapping task performance in both younger and older participants suggesting the availability of cognitive plasticity in both age groups. Improvement was equivalent among age groups in response speed and performance variability but larger in response accuracy for older adults. The results suggest that time-sharing skills can be substantially improved in older adults.

Detecting transient changes in dynamic displays: the more you look, the less you see.

OBJECTIVE: Two experiments examined the detectability of transient changes in cluttered and dynamic displays and optimal scan strategies for performance. BACKGROUND: Research has demonstrated that onset changes are prioritized by the attention system and onsets are often used to signal important display changes. However, research has mostly used uncluttered, static displays and has largely ignored the role of scan strategy. METHOD: We had participants monitor a cluttered and dynamic display and respond when an object changed color or onset abruptly. Scan strategies were also evaluated. In another experiment participants were instructed to use particular strategies to detect changes. RESULTS: Consistent with previous results, onset events were detected better than were color change events. Scan strategy accounted for a large proportion of variance in detection performance. Participants who made few eye movements performed best. Participants who actively scanned the display performed worst. When poor performers were instructed to make few eye movements, their performance matched that of the best performers. CONCLUSION: Onset alerts can be an effective means of signaling important events in complex displays. Additionally, scan strategy plays an important role in the detection of transient events. APPLICATION: These results have important implications for training operators to search for transient changes within dynamic and cluttered displays.

Training effects on dual-task performance: are there age-related differences in plasticity of attentional control?

A number of studies have suggested that attentional control skills required to perform 2 tasks concurrently become impaired with age (A. A. Hartley, 1992; J. M. McDowd & R. J. Shaw, 2000). A. A. Hartley (2001) recently observed that the age-related differences in dual-task performance were larger when the 2 tasks required similar motor responses. The present study examined the extent to which age-related deficits in dual-task performance or time sharing--in particular, dual-task performance of 2 discrimination tasks with similar motor requirements--can be moderated by training. The results indicate that, even when the 2 tasks required similar motor responses, both older and younger adults could learn to perform the tasks faster and more accurately. Moreover, the improvement in performance generalized to new task combinations involving new stimuli. Therefore, it appears that training can substantially improve dual-task processing skills in older adults.