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The introduction of shared autonomous vehicles into the transport system is suggested to bring significant impacts on traffic conditions, road safety and emissions, as well as overall reshaping travel behaviour. Compared with a private autonomous vehicle, a shared automated vehicle (SAV) is associated with different willingness-to-adopt and willingness-to-pay characteristics. An important aspect of future SAV adoption is the presence of other passengers in the SAV—often people unknown to the cotravellers. This study presents a cross-country exploration of user preferences and WTP calculations regarding mode choice between a private non-autonomous vehicle, and private and shared autonomous vehicles. To explore user preferences, the study launched a survey in seven European countries, including a stated-preference experiment of user choices. To model and quantify the effect of travel mode attributes and socio-demographic characteristics, the study employs a mixed logit model. The model results were the basis for calculating willingness-to-pay values for all countries and travel modes, and provide insight into the significant heterogeneous, gender-wise effect of cotravellers in the choice to use an SAV. The study results highlight the importance of analysis of the effect of SAV attributes and shared-ride conditions on the future acceptance and adoption rates of such services.
Amalia Polydoropoulou; Ioannis Tsouros; Nikolas Thomopoulos; Cristina Pronello; Arnór Elvarsson; Haraldur Sigþórsson; Nima Dadashzadeh; Kristina Stojmenova; Jaka Sodnik; Stelios Neophytou; Domokos Esztergár-Kiss; Jamil Hamadneh; Graham Parkhurst; Shelly Etzioni; Yoram Shiftan; Floridea Di Ciommo. Who Is Willing to Share Their AV? Insights about Gender Differences among Seven Countries. Sustainability 2021, 13, 4769 .
AMA StyleAmalia Polydoropoulou, Ioannis Tsouros, Nikolas Thomopoulos, Cristina Pronello, Arnór Elvarsson, Haraldur Sigþórsson, Nima Dadashzadeh, Kristina Stojmenova, Jaka Sodnik, Stelios Neophytou, Domokos Esztergár-Kiss, Jamil Hamadneh, Graham Parkhurst, Shelly Etzioni, Yoram Shiftan, Floridea Di Ciommo. Who Is Willing to Share Their AV? Insights about Gender Differences among Seven Countries. Sustainability. 2021; 13 (9):4769.
Chicago/Turabian StyleAmalia Polydoropoulou; Ioannis Tsouros; Nikolas Thomopoulos; Cristina Pronello; Arnór Elvarsson; Haraldur Sigþórsson; Nima Dadashzadeh; Kristina Stojmenova; Jaka Sodnik; Stelios Neophytou; Domokos Esztergár-Kiss; Jamil Hamadneh; Graham Parkhurst; Shelly Etzioni; Yoram Shiftan; Floridea Di Ciommo. 2021. "Who Is Willing to Share Their AV? Insights about Gender Differences among Seven Countries." Sustainability 13, no. 9: 4769.
Autonomous vehicles are expected to take complete control of the driving process, enabling the former drivers to act as passengers only. This could lead to increased sickness as they can be engaged in tasks other than driving. Adopting different sickness mitigation techniques gives us unique types of motion sickness in autonomous vehicles to be studied. In this paper, we report on a study where we explored the possibilities of assessing motion sickness with electrogastrography (EGG), a non-invasive method used to measure the myoelectric activity of the stomach, and its potential usage in autonomous vehicles (AVs). The study was conducted in a high-fidelity driving simulator with a virtual reality (VR) headset. There separate EGG measurements were performed: before, during and after the driving AV simulation video in VR. During the driving, the participants encountered two driving environments: a straight and less dynamic highway road and a highly dynamic and curvy countryside road. The EGG signal was recorded with a proprietary 3-channel recording device and Ag/AgCl cutaneous electrodes. In addition, participants were asked to signalize whenever they felt uncomfortable and nauseated by pressing a special button. After the drive they completed also the Simulator Sickness Questionnaire (SSQ) and reported on their overall subjective perception of sickness symptoms. The EGG results showed a significant increase of the dominant frequency (DF) and the percentage of the high power spectrum density (FSD) as well as a significant decrease of the power spectrum density Crest factor (CF) during the AV simulation. The vast majority of participants reported nausea during more dynamic conditions, accompanied by an increase in the amplitude and the RMS value of EGG. Reported nausea occurred simultaneously with the increase in EGG amplitude. Based on the results, we conclude that EGG could be used for assessment of motion sickness in autonomous vehicles. DF, CF and FSD can be used as overall sickness indicators, while the relative increase in amplitude of EGG signal and duration of that increase can be used as short-term sickness indicators where the driving environment may affect the driver.
Timotej Gruden; Nenad Popović; Kristina Stojmenova; Grega Jakus; Nadica Miljković; Sašo Tomažič; Jaka Sodnik. Electrogastrography in Autonomous Vehicles—An Objective Method for Assessment of Motion Sickness in Simulated Driving Environments. Sensors 2021, 21, 550 .
AMA StyleTimotej Gruden, Nenad Popović, Kristina Stojmenova, Grega Jakus, Nadica Miljković, Sašo Tomažič, Jaka Sodnik. Electrogastrography in Autonomous Vehicles—An Objective Method for Assessment of Motion Sickness in Simulated Driving Environments. Sensors. 2021; 21 (2):550.
Chicago/Turabian StyleTimotej Gruden; Nenad Popović; Kristina Stojmenova; Grega Jakus; Nadica Miljković; Sašo Tomažič; Jaka Sodnik. 2021. "Electrogastrography in Autonomous Vehicles—An Objective Method for Assessment of Motion Sickness in Simulated Driving Environments." Sensors 21, no. 2: 550.
Autonomous vehicles are anticipated to play an important role on future mobility offering encouraging solutions to today’s transport problems. However, concerns of the public, which can affect the AVs’ uptake, are yet to be addressed. This study presents relevant findings of an online survey in eight European countries. First, 1639 responses were collected in Spring 2020 on people’s commute, preferred transport mode, willingness to use AVs and demographic details. Data was analyzed for the entire dataset and for vulnerable road users in particular. Results re-confirm the long-lasting discourse on the importance of safety on the acceptance of AVs. Spearman correlations show that age, gender, education level and number of household members have an impact on how people may be using or allowing their children to use the technology, e.g., with or without the presence of a human supervisor in the vehicle. Results on vulnerable road users show the same trend. The elderly would travel in AVs with the presence of a human supervisor. People with disabilities have the same proclivity, however their reactions were more conservative. Next to safety, reliability, affordability, cost, driving pleasure and household size may also impact the uptake of AVs and shall be considered when designing relevant policies.
Miltos Kyriakidis; Jaka Sodnik; Kristina Stojmenova; Arnór Elvarsson; Cristina Pronello; Nikolas Thomopoulos. The Role of Human Operators in Safety Perception of AV Deployment—Insights from a Large European Survey. Sustainability 2020, 12, 9166 .
AMA StyleMiltos Kyriakidis, Jaka Sodnik, Kristina Stojmenova, Arnór Elvarsson, Cristina Pronello, Nikolas Thomopoulos. The Role of Human Operators in Safety Perception of AV Deployment—Insights from a Large European Survey. Sustainability. 2020; 12 (21):9166.
Chicago/Turabian StyleMiltos Kyriakidis; Jaka Sodnik; Kristina Stojmenova; Arnór Elvarsson; Cristina Pronello; Nikolas Thomopoulos. 2020. "The Role of Human Operators in Safety Perception of AV Deployment—Insights from a Large European Survey." Sustainability 12, no. 21: 9166.
Objective: To identify driving characteristics of fit-, unfit-, and conditionally fit-to-drive neurological patient populations using a driving simulator with three high-risk scenarios comprising rural, highway, and urban environments. Methods: The study included 91 neurological patients undergoing a multidisciplinary assessment for driver’s license revalidation, consisting of a clinical, neuropsychological, functional, and on-road evaluation. The groups drove through three independent driving scenarios, during which a variety of measures describing reaction time, vehicular control, and traffic rule compliance were performed. One-way analysis of variance (ANOVA) with Bonferroni correction was used for group comparison, independently for each driving scenario, and Pearson correlations were calculated between simulator variables and neuropsychological test scores. Results: The fit- and unfit-to-drive population significantly differed (p < .05) in reaction times, regardless of the scenario. No significant differences in traffic rule compliance or vehicular control parameters were observed in the rural environment (p > .05). On the highway, the unfit group exhibited greater variability of steering wheel angle, higher steering reversal rate, and a higher rate of turn signal errors. In the urban environment, the unfit group oversped more, had more collisions, and exhibited greater lane position variability. The latter, along with reaction times in the rural and highway scenarios, was also shown to significantly differ between the conditional and unfit group (p < .05). No significant differences were observed between the fit and the conditional group (p > .05). Weak to moderate associations (range: −0.5 to 0.29) between neuropsychological tests and various simulator variables were also observed. Conclusions: Our results show that driving simulators are able to capture differences between (fit- and unfit-to-drive) neurological patient populations and therefore bear the potential for being used as a deficit-independent screening, assessment, or rehabilitation tool. The conditionally-fit-to-drive group exhibited less discriminative features, which points to greater importance of human judgment for this population. The observation that differences in most of the parameters were environment-dependent suggests that developers of future driver simulation tools should carefully design scenarios in order to fully exploit their assessment potential.
Lenart Motnikar; Kristina Stojmenova; Urša Čižman Štaba; Tara Klun; Karmen Resnik Robida; Jaka Sodnik. Exploring driving characteristics of fit- and unfit-to-drive neurological patients: a driving simulator study. Traffic Injury Prevention 2020, 21, 359 -364.
AMA StyleLenart Motnikar, Kristina Stojmenova, Urša Čižman Štaba, Tara Klun, Karmen Resnik Robida, Jaka Sodnik. Exploring driving characteristics of fit- and unfit-to-drive neurological patients: a driving simulator study. Traffic Injury Prevention. 2020; 21 (6):359-364.
Chicago/Turabian StyleLenart Motnikar; Kristina Stojmenova; Urša Čižman Štaba; Tara Klun; Karmen Resnik Robida; Jaka Sodnik. 2020. "Exploring driving characteristics of fit- and unfit-to-drive neurological patients: a driving simulator study." Traffic Injury Prevention 21, no. 6: 359-364.
The ability to measure drivers’ physiological responses is important for understanding their state and behavior under different driving conditions. Such measurements can be used in the development of novel user interfaces, driver profiling, advanced driver assistance systems, etc. In this paper, we present a user study in which we performed an evaluation of two commercially available wearable devices for assessment of drivers’ physiological signals. Empatica’s E4 wristband measures blood volume pulse (BVP), inter-beat interval (IBI), galvanic skin response (GSR), temperature, and acceleration. Bittium’s Faros 360 is an electrocardiographic (ECG) device that can record up to 3-channel ECG signals. The aim of this study was to explore the use of such devices in a dynamic driving environment and their ability to differentiate between different levels of driving demand. Twenty-two participants (eight female, 14 male) aged between 18 and 45 years old participated in the study. The experiment compared three phases: Baseline (no driving), easy driving scenario, and demanding driving scenario. Mean and median heart rate variability (HRV), standard deviation of R–R intervals (SDNN), HRV variables for shorter time frames (standard deviation of the average R–R intervals over a shorter period—SDANN and mean value of the standard deviations calculated over a shorter period—SDNN index), HRV variables based on successive differences (root mean square of successive differences—RMSSD and percentage of successive differences, greater than 50 ms—pNN50), skin temperature, and GSR were observed in each phase. The results showed that motion artefacts due to driving affect the GSR recordings, which may limit the use of wrist-based wearable devices in a driving environment. In this case, due to the limitations of the photoplethysmography (PPG) sensor, E4 only showed differences between non-driving and driving phases but could not differentiate between different levels of driving demand. On the other hand, the results obtained from the ECG signals from Faros 360 showed statistically significant differences also between the two levels of driving demand.
Timotej Gruden; Kristina Stojmenova; Jaka Sodnik; Grega Jakus. Assessing Drivers’ Physiological Responses Using Consumer Grade Devices. Applied Sciences 2019, 9, 5353 .
AMA StyleTimotej Gruden, Kristina Stojmenova, Jaka Sodnik, Grega Jakus. Assessing Drivers’ Physiological Responses Using Consumer Grade Devices. Applied Sciences. 2019; 9 (24):5353.
Chicago/Turabian StyleTimotej Gruden; Kristina Stojmenova; Jaka Sodnik; Grega Jakus. 2019. "Assessing Drivers’ Physiological Responses Using Consumer Grade Devices." Applied Sciences 9, no. 24: 5353.
In the era of technological advances and innovations in transportation technologies, application of driving simulators for the investigation and assessment of the driving process provides a safe and suitable testing environment. Although driving simulators are crucial for further improvements in transportation, it is important to resolve one of their main disadvantages–simulator sickness. Therefore, suitable methods for the assessment of simulator sickness are required. The main aim of this paper was to present a non-invasive method for assessing simulator sickness by recording gastric myoelectrical activity–electrogastrography. Open-source hardware for electrogastrography together with recordings obtained in 13 healthy volunteers is presented, and the main aspects of signal processing for artifact cancellation and feature extraction were discussed. Based on the obtained results, it was concluded that slow-wave electrical gastric activity can be recorded during driving simulation by following adequate recommendations and that proposed features could be beneficial in describing non-ordinary electrogastrography signals.
Nenad B. Popović; Nadica Miljković; Kristina Stojmenova; Grega Jakus; Milana Prodanov; Jaka Sodnik. Lessons Learned: Gastric Motility Assessment During Driving Simulation. Sensors 2019, 19, 3175 .
AMA StyleNenad B. Popović, Nadica Miljković, Kristina Stojmenova, Grega Jakus, Milana Prodanov, Jaka Sodnik. Lessons Learned: Gastric Motility Assessment During Driving Simulation. Sensors. 2019; 19 (14):3175.
Chicago/Turabian StyleNenad B. Popović; Nadica Miljković; Kristina Stojmenova; Grega Jakus; Milana Prodanov; Jaka Sodnik. 2019. "Lessons Learned: Gastric Motility Assessment During Driving Simulation." Sensors 19, no. 14: 3175.
Various studies show that drowsiness reduces driver alertness and can significantly affect driver performance. In this paper, we investigate the effect of drowsiness on the interaction with the in-vehicle infotainment system (IVIS) while driving. The motivation was to investigate whether a specific type of user interface can provide better performance and lower distraction when the driver is drowsy. The users were asked to navigate a vehicle in a driving simulator and simultaneously perform a set of tasks of varying complexity first when they were rested and alert and then when they were drowsy, after 7 h without sleep. A hierarchical, list-based menu was presented using a stereoscopic head-up display (HUD) and a head-down display (HDD). Based on the results, no general and statistically significant connection was found between drowsiness and driving performance. Surprisingly, the secondary task performance was even better when participants were drowsy, which was evident from the faster task completion times. This could be attributed to extra efforts invested in executing tasks as a result of the participants being aware of their drowsiness. However, when comparing the participants’ performance using HUD and HDD displays, the results showed that using HUD introduces less mental fatigue than using HDD but only in rested and alert condition. No significant difference between the displays was found in the drowsy state.
David Grogna; Kristina Stojmenova; Grega Jakus; Miguel Barreda-Ángeles; Jacques G. Verly; Jaka Sodnik. The impact of drowsiness on in-vehicle human-machine interaction with head-up and head-down displays. Multimedia Tools and Applications 2018, 77, 27807 -27827.
AMA StyleDavid Grogna, Kristina Stojmenova, Grega Jakus, Miguel Barreda-Ángeles, Jacques G. Verly, Jaka Sodnik. The impact of drowsiness on in-vehicle human-machine interaction with head-up and head-down displays. Multimedia Tools and Applications. 2018; 77 (21):27807-27827.
Chicago/Turabian StyleDavid Grogna; Kristina Stojmenova; Grega Jakus; Miguel Barreda-Ángeles; Jacques G. Verly; Jaka Sodnik. 2018. "The impact of drowsiness on in-vehicle human-machine interaction with head-up and head-down displays." Multimedia Tools and Applications 77, no. 21: 27807-27827.
This paper presents a driving simulator study in which we investigated whether the Eye Tribe eye tracker (ET) is capable of assessing changes in the cognitive load of drivers through oculography and pupillometry. In the study, participants were asked to drive a simulated vehicle and simultaneously perform a set of secondary tasks with different cognitive complexity levels. We measured changes in eye properties, such as the pupil size, blink rate and fixation time. We also performed a measurement with a Detection Response Task (DRT) to validate the results and to prove a steady increase of cognitive load with increasing secondary task difficulty. The results showed that the ET precisely recognizes an increasing pupil diameter with increasing secondary task difficulty. In addition, the ET shows increasing blink rates, decreasing fixation time and narrowing of the attention field with increasing secondary task difficulty. The results were validated with the DRT method and the secondary task performance. We conclude that the Eye Tribe ET is a suitable device for assessing a driver's cognitive load.
Tomaž Čegovnik; Kristina Stojmenova; Grega Jakus; Jaka Sodnik. An analysis of the suitability of a low-cost eye tracker for assessing the cognitive load of drivers. Applied Ergonomics 2018, 68, 1 -11.
AMA StyleTomaž Čegovnik, Kristina Stojmenova, Grega Jakus, Jaka Sodnik. An analysis of the suitability of a low-cost eye tracker for assessing the cognitive load of drivers. Applied Ergonomics. 2018; 68 ():1-11.
Chicago/Turabian StyleTomaž Čegovnik; Kristina Stojmenova; Grega Jakus; Jaka Sodnik. 2018. "An analysis of the suitability of a low-cost eye tracker for assessing the cognitive load of drivers." Applied Ergonomics 68, no. : 1-11.
The Detection-Response Task is a method for assessing the attentional effects of cognitive load in a driving environment. Drivers are presented with a sensory stimulus every 3–5 s, and are asked to respond to it by pressing a button attached to their finger. Response times and hit rates are interpreted as indicators of the attentional effect of cognitive load. The stimuli can be visual, tactile and auditory, and are chosen based on the type of in-vehicle system or device that is being evaluated. Its biggest disadvantage is that the method itself also affects the driver’s performance and secondary task completion times. Nevertheless, this is an easy to use and implement method, which allows relevant assessment and evaluation of in-vehicle systems. By following the recommendations and taking into account its limitations, researchers can obtain reliable and valuable results on the attentional effects of cognitive load on drivers.
Kristina Stojmenova; Jaka Sodnik. Detection-Response Task—Uses and Limitations. Sensors 2018, 18, 594 .
AMA StyleKristina Stojmenova, Jaka Sodnik. Detection-Response Task—Uses and Limitations. Sensors. 2018; 18 (2):594.
Chicago/Turabian StyleKristina Stojmenova; Jaka Sodnik. 2018. "Detection-Response Task—Uses and Limitations." Sensors 18, no. 2: 594.
Objectives: The detection response task (DRT) is a method for measuring attentional effects of secondary tasks on a driver's cognitive load by measuring response times and hit rates to different types of stimuli as indirect indicators of increased cognitive load. ISO 17488 (International Organization for Standardization 2016) only provides guidelines for the technical implementation and measurement methods for the visual and tactile versions (use of visual and tactile stimuli) of the DRT method. This article presents a study with the goal of finding the most appropriate auditory stimulus for the implementation of an auditory version of the DRT method. Methods: This article presents the results of an experiment in which responses to 7 different auditory DRT stimuli—varying in frequency—were compared while inducing users' cognitive load with a modified n-back task. The experiment was conducted in a surrogate driving environment and in a within-subject design. Response times, hit rates, and secondary task performances were observed as indicators of increased cognitive load. Results: Significantly shorter response times were found for the white noise signal compared to single-frequency signals. However, the largest differences in response times, for trials without and with a cognitive task, were found for 4- and 8-kHz single-frequency signals. No significant differences were found for hit rates and secondary task performances between the different stimuli. Conclusions: Consistent significant differences in response times for all tested stimuli prove that the auditory DRT variant is also sensitive to changes in cognitive load. The mean increase in response times of more than 25% for 4- and 8-kHz signals for trials with a cognitive task compared to trials without one indicates that one of these signals could be used as a potential auditory stimulus for the auditory DRT variant.
Kristina Stojmenova; Franco Policardi; Jaka Sodnik. On the selection of stimulus for the auditory variant of the detection response task method for driving experiments. Traffic Injury Prevention 2017, 19, 23 -27.
AMA StyleKristina Stojmenova, Franco Policardi, Jaka Sodnik. On the selection of stimulus for the auditory variant of the detection response task method for driving experiments. Traffic Injury Prevention. 2017; 19 (1):23-27.
Chicago/Turabian StyleKristina Stojmenova; Franco Policardi; Jaka Sodnik. 2017. "On the selection of stimulus for the auditory variant of the detection response task method for driving experiments." Traffic Injury Prevention 19, no. 1: 23-27.
The Detection Response Task (DRT) is a method for measuring the attentional effects of secondary tasks on driver’s cognitive load and was standardized by ISO in 2016 [1]. It observes response times and stimuli detection performance (hit rates) to different stimuli types – visual, tactile and auditory –as indirect indicators of changes in cognitive load. ISO 17488 [1] standard provides instructions for technical implementation and measurement methods only for the visual and tactile versions (use of visual and tactile stimuli) of the DRT method. In this study, we try to find the most appropriate auditory stimulus for technical implementation also for the auditory version of the method. This paper presents results of a user study in which responses to different auditory DRT stimuli were compared while inducing users’ cognitive load with a modified n – back task, also known as Delayed Digit Recall task [2].
Kristina Stojmenova; Jaka Sodnik. Determination of Auditory Stimuli for the Auditory Variant of the Detection Response Task Method. Advances in Intelligent Systems and Computing 2017, 597, 435 -443.
AMA StyleKristina Stojmenova, Jaka Sodnik. Determination of Auditory Stimuli for the Auditory Variant of the Detection Response Task Method. Advances in Intelligent Systems and Computing. 2017; 597 ():435-443.
Chicago/Turabian StyleKristina Stojmenova; Jaka Sodnik. 2017. "Determination of Auditory Stimuli for the Auditory Variant of the Detection Response Task Method." Advances in Intelligent Systems and Computing 597, no. : 435-443.
Objectives: In this article, we evaluate the sensitivity to cognitive load of 3 versions of the Detection Response Task method (DRT), proposed in ISO Draft Standard DIS-17488. Methods: We present a user study with 30 participants in which we compared the sensitivity to cognitive load of visual, audio, and tactile DRT in a simulated driving environment. The amount of cognitive load was manipulated with secondary n-back tasks at 2 levels of difficulty (0-back and 1-back). We also explored whether the DRT method is least sensitive to cognitive load when the stimuli and secondary task are of the same modality. For this purpose, we used 3 forms to present the n-back task stimuli: visual, audio, and tactile. Responses to the task were always vocal. The experiment was based on a between-subject design (the DRT modalities) with 2 levels of within-subject design study (modalities and difficulty of the secondary n-back tasks). The participants' primary task in the study was to drive safely, and a second priority was to answer to DRT stimuli and perform secondary tasks. Results: The results indicate that all 3 versions of the DRT tested were sensitive to detecting the difference in cognitive load between the reference driving period and driving and engaging in the secondary tasks. Only the visual DRT discriminated between the 0-back and 1-back conditions on mean response time. Contrary to expectations, no interaction was observed between DRT modality and the stimuli modality used for presentation of the secondary tasks. Conclusions: None of the 3 methods of presenting DRT stimuli showed a consistent advantage in sensitivity in differentiating multiple levels of cognitive load if all response times, hit rates, and secondary task performance are considered. If only response time is considered, the visual presentation of the DRT stimulus used in this study showed some advantages. In interpreting these data, it should be noted that the methods of DRT stimulus presentation varied somewhat from the currently proposed draft ISO standard and it is possible that the relative salience level of the visual DRT stimulus influenced the findings. It is further suggested that more than 2 levels of difficulty of the n-back task should be considered for further investigation of the relative sensitivity of different DRT stimuli modalities. Parameters that indicate change in cognitive load (response time, hit rate, task performance) should be analyzed together in assessing the overall impact on the driver and not individually, in order to obtain a fuller insight of the assessed cognitive load.
Kristina Stojmenova; Grega Jakus; Jaka Sodnik. Sensitivity evaluation of the visual, tactile, and auditory detection response task method while driving. Traffic Injury Prevention 2016, 18, 431 -436.
AMA StyleKristina Stojmenova, Grega Jakus, Jaka Sodnik. Sensitivity evaluation of the visual, tactile, and auditory detection response task method while driving. Traffic Injury Prevention. 2016; 18 (4):431-436.
Chicago/Turabian StyleKristina Stojmenova; Grega Jakus; Jaka Sodnik. 2016. "Sensitivity evaluation of the visual, tactile, and auditory detection response task method while driving." Traffic Injury Prevention 18, no. 4: 431-436.