| 1. |
- Ljung Aust, Mikael, 1973, et al.
(författare)
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Final measures (Deliverable 5.5)
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The main objective of WP5 has been to run a set of field trials with naïve users (i.e. not experts involved in the development of the measures) for all nudging and coaching measures developed in WP2-4. Then, given the outcome of the field trials, the task has been to analyse which impacts these measures may have on road safety along with the cost of implementing them in vehicle fleets and/or infrastructure. All these activities have taken place in Tasks 5.4 (Data collection) and 5.6 (Data analysis).
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| 2. |
- Ljung Aust, Mikael, 1973, et al.
(författare)
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Results of field trials (Deliverable 5.4)
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The main objective of WP5 is to run a set of field trials with naïve users (i.e. not experts involved in the development of the measures) for all nudging and coaching measures developed in WP2-4. Field trials with naïve users are necessary in order to validate the estimated effectiveness of each measure. The field trials were set up in as realistic settings as possible, given the possibilities to implement/distribute each measure. This deliverable gives a short description of the field trial setup for each measure, and then reports the effects of the nudge on road user behaviour.
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| 3. |
- Nilsson, Emma, 1982, et al.
(författare)
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Let Complexity Bring Clarity: A Multidimensional Assessment of Cognitive Load Using Physiological Measures
- 2022
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Ingår i: Frontiers in Neuroergonomics. - : Frontiers Media SA. - 2673-6195. ; 3
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Tidskriftsartikel (refereegranskat)abstract
- The effects of cognitive load on driver behavior and traffic safety are unclear and in need of further investigation. Reliable measures of cognitive load for use in research and, subsequently, in the development and implementation of driver monitoring systems are therefore sought. Physiological measures are of interest since they can provide continuous recordings of driver state. Currently, however, a few issues related to their use in this context are not usually taken into consideration, despite being well-known. First, cognitive load is a multidimensional construct consisting of many mental responses (cognitive load components) to added task demand. Yet, researchers treat it as unidimensional. Second, cognitive load does not occur in isolation; rather, it is part of a complex response to task demands in a specific operational setting. Third, physiological measures typically correlate with more than one mental state, limiting the inferences that can be made from them individually. We suggest that acknowledging these issues and studying multiple mental responses using multiple physiological measures and independent variables will lead to greatly improved measurability of cognitive load. To demonstrate the potential of this approach, we used data from a driving simulator study in which a number of physiological measures (heart rate, heart rate variability, breathing rate, skin conductance, pupil diameter, eye blink rate, eye blink duration, EEG alpha power, and EEG theta power) were analyzed. Participants performed a cognitively loading n-back task at two levels of difficulty while driving through three different traffic scenarios, each repeated four times. Cognitive load components and other coinciding mental responses were assessed by considering response patterns of multiple physiological measures in relation to multiple independent variables. With this approach, the construct validity of cognitive load is improved, which is important for interpreting results accurately. Also, the use of multiple measures and independent variables makes the measurements (when analyzed jointly) more diagnostic—that is, better able to distinguish between different cognitive load components. This in turn improves the overall external validity. With more detailed, diagnostic, and valid measures of cognitive load, the effects of cognitive load on traffic safety can be better understood, and hence possibly mitigated.
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| 4. |
- Nilsson, Emma, 1982, et al.
(författare)
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On-to-off-path gaze shift cancellations lead to gaze concentration in cognitively loaded car drivers: A simulator study exploring gaze patterns in relation to a cognitive task and the traffic environment
- 2020
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Ingår i: Transportation Research Part F: Traffic Psychology and Behaviour. - : Elsevier BV. - 1369-8478. ; 75, s. 1-15
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Tidskriftsartikel (refereegranskat)abstract
- Appropriate visual behaviour is necessary for safe driving. Many previous studies have found that when performing non-visual cognitive tasks, drivers typically display an increased amount of on-path glances, along with a deteriorated visual scanning pattern towards potential hazards at locations outside their future travel path (off-path locations). This is often referred to as a gaze concentration effect. However, what has not been explored is more precisely how and when gaze concentration arises in relation to the cognitive task, and to what extent the timing of glances towards traffic-situation relevant off-path locations is affected. To investigate these specific topics, a driving simulator study was carried out. Car drivers’ visual behaviour during execution of a cognitive task (n-back) was studied during two traffic scenarios; one when driving through an intersection and one when passing a hidden exit. Aside from the expected gaze concentration effect, several novel findings that may explain this effect were observed. It was found that gaze shifts from an on-path to an off-path location were inhibited during increased cognitive load. However, gaze shifts in the other direction, that is, from an off-path to an on-path location, remained unaffected. This resulted in on-path glances increasing in duration, while off-path glances decreased in number. Furthermore, the inhibited off-path glances were typically not compensated for later. That is, off-path glances were cancelled, not delayed. This was the case both in relation to the cognitive task (near-term) and the traffic environment (far-term). There was thus a general reduction in the number of glances towards situationally relevant off-path locations, but the timing of the remaining glances was unaffected. These findings provide a deeper understanding of the mechanism behind gaze concentration and can contribute to both understanding and prediction of safety relevant effects of cognitive load in car drivers.
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| 5. |
- Sjörs Dahlman, Anna, 1981-, et al.
(författare)
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In-vehicle fragrance administration as a countermeasure for driver fatigue
- 2024
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Ingår i: Accident Analysis and Prevention. - : Elsevier. - 0001-4575 .- 1879-2057. ; 195
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Tidskriftsartikel (refereegranskat)abstract
- Driver fatigue is a contributing factor in about 10–30% of all fatal crashes. Prevention of fatigue-related crashes relies on robust detection of driver fatigue and application of effective countermeasures. A potential countermeasure is fragrance administration since odors can have alerting effects on humans. The aim here was to investigate if a fragrance incorporating trigeminal components could be used as an in-vehicle countermeasure for driver fatigue.The fragrance was tested in a driving simulator with 21 healthy but sleep-deprived participants. Each participant performed a monotonous driving task twice, once with active fragrance containing a trigeminal component and once with olfactory fragrance, in a cross-over single-blind design. The order of trigeminal/olfactory fragrance was randomized and blinded to the participants. Both fragrances (trigeminal/olfactory) were administered either when the participant fell asleep (defined as eye closure > 3 s) or after approximately 45 min if the participant did not fall asleep.Self-reported sleepiness was assessed using the Karolinska Sleepiness Scale (KSS) every 5 min during driving. Variability in speed and lateral position and line crossing frequency were logged for each drive to measure driving performance. Heart rate measurements (ECG) and eye blinks (EOG) were collected to investigate potential arousing effects of the fragrance and to track objective signs of sleepiness.
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| 6. |
- Svärd, Malin, 1985, et al.
(författare)
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Do Car Drivers Respond Earlier to Close Lateral Motion Than to Looming?
- 2022
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Ingår i: 12th International Conference on Methods and Techniques in Behavioral Research and 6th Seminar on Behavioral Methods. - 9789074821940 ; 2
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Konferensbidrag (refereegranskat)abstract
- It is essential to understand drivers’ responses to visual stimuli when analyzing or reconstructing driver behavior in critical traffic situations. In a controlled experiment, drivers’ on-road glances relevant to a situation may however be obscured by the presence of check glances which are not induced by the visual input that the experiment intends to study. The purpose of this work is to compare five methods to reduce the influence check glances may have on the results in studies of drivers’ glance responses. We apply the methods to a comparison of driver glance response times in a critical lead vehicle brake event (characterized by strong looming) and a non-critical close cut-in event (characterized by a distinct lateral motion), using data from a previously conducted driving simulator experiment. Without the noise added to the analysis from the check glances, our study shows that drivers look back towards the road in front earlier when exposed to close lateral motion, than when exposed to looming. We conclude that a careful data selection process aiming to minimize the influence of potential check glances is important to ensure relevance of the results in glance response studies.
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| 7. |
- Svärd, Malin, 1985, et al.
(författare)
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Using naturalistic and driving simulator data to model driver responses to unintentional lane departures
- 2024
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Ingår i: Transportation Research Part F: Traffic Psychology and Behaviour. - 1369-8478. ; 100, s. 361-387
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Tidskriftsartikel (refereegranskat)abstract
- Unintentional lane departures on straight roads cause many road fatalities each year. The objective of this study was to explore and model drivers’ recovery steering maneuvers in unintentional drift situations, to enable the prospective safety benefit assessment of lane departure warning and avoidance systems through counterfactual simulations. The timing and amplitude of the steering adjustments drivers make to avoid lane departure were studied over three data sets with different origins, consisting of both naturalistic data and experimental data from a driving simulator study. With respect to timing, the main finding was that visually distracted drivers often initiate the corrective steering response prior to looking back towards the road, demonstrating that lane-keeping information in the visual periphery is sufficient to trigger the response. As for steering amplitude, the observed amplitudes were correlated against different lane departure risk metrics from the literature, resulting in a model capable of accounting for human behavior across all three data sets with good performance. Surprisingly, a very simple model (which describes the steering amplitude as increasing quadratically with the vehicle's orientation to the road) predicted the amplitude of the primary corrective steering adjustment better than models based on more complex lane departure risk metrics. This result indicates that drivers scale the amplitude of their steering adjustment to the steering input needed to get the vehicle back in the lane already at first response. However, it was possible to obtain a similar model fit using a more complex threshold model, with different dynamics depending on the vehicle's current orientation to the road. We discuss how these findings can be applied to models of human steering for safety benefit assessment.
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| 8. |
- Tivesten, Emma, 1968, et al.
(författare)
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The influence of alcohol and automation on drivers’ visual behavior during test track driving
- 2023
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Ingår i: Transportation Research Part F: Traffic Psychology and Behaviour. - 1369-8478. ; 95, s. 215-227
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Tidskriftsartikel (refereegranskat)abstract
- Background: Driving under the influence of alcohol severely increases crash risk. Impairment detection during driving is therefore key to improve traffic safety. However, future detection systems need to capture impairment for more reasons than alcohol intoxication and must also function in all driving modes (manual, assisted, autonomous). Driver Monitoring Systems (DMS) are promising candidates for such broader impairment detection. Method: A test track study investigated the effects of alcohol intoxication on drivers’ visual behavior both when just driving and when engaged in a non-driving related task. Twenty-six participants performed two drives: 1) sober baseline, 2) with a target blood alcohol concentration of 0.1%. The participants drove in either manual, assisted, or autonomous drive (AD) mode. Results: Intoxication influenced glance behavior in all driving modes. It was most evident during visually demanding non-driving related tasks where it resulted in longer single and total off-path glance durations. Additionally, when just driving in manual mode, almost one third of the drivers displayed gaze concentration to the forward roadway when intoxicated. For sober driving, the difference in visual behavior between manual and assisted mode were moderate. In contrast, there was a huge shift towards longer off-path glances, lower percent road center, and lower off-path glance frequency in AD mode. Conclusions: Intoxication clearly affects drivers’ on/off road glance behavior. However, it is necessary to account for both driving mode and engagement in non-driving related tasks to reliably distinguish sober from drunk driving. Glance metrics has the potential to serve as a sub-set of indicators for a broader DMS-based detection of impaired driving, which can inform the decisions on when to activate in-vehicle countermeasures.
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