Eye-movements in real curve driving: pursuit-like optokinesis in vehicle frame of reference, stability in an allocentric reference coordinate system

Looking at the future path and/or the tangent point (TP) have been identified as car drivers’ gaze targets in many studies on curve driving. Yet little is known in detail about these "fixations to the road". We quantitatively analyse gaze behavior at the level of individual fixations in real on-road data. We find that while gaze tracks the TP area, this pattern consists of fast optokinetic movements (smooth pursuit and fast resetting saccadic movements). Gaze is not “fixed” to the TP. We also relate eye-movements to a reference direction fixed to a point on the trajectory of the vehicle (curve exit), showing that fixations lose their pursuit-like character in this rotating system. The findings are discussed in terms of steering models and neural levels of oculomotor control

Etenemistä ennakoivat katseet kaarreajossa

In the visual control of locomotion, gaze is used to sample information in an anticipatory manner. In car driving, this anticipation functions at both a short and long time distance. At the short time distance, gaze leads the locomotion with a small (1‒3 s) time headway. Many steering models have explained this behavior by interpreting that drivers track a steering point on the road to obtain visual information which is directly translated to steering actions. This gaze behaviour can be called guiding fixations, because the gaze is providing information for the online control of the steering. At the long time distance, gaze serves trajectory planning by picking up information from the road further ahead. In curves, a part of the road can be visible in highly eccentric positions relative to the typical guiding fixations direction. In these situations, the information needs of the trajectory planning can result in eccentric look-ahead fixations toward the curve. The role of these fixations in the visual control of locomotion is not well understood. In this thesis, I have developed algorithmical methods for the identification of look-ahead fixations from eye movement data collected with an instrumented vehicle on real roads. In a series of three experiments, gaze behavior in curves was studied. The effects of driving experience and cognitive load were also investigated. In general, fixation distributions do not suggest a clear division between guiding and look-ahead fixations. However, a clear tail of eccentric fixations is present in the distributions, which can be operationally defined as look-ahead fixations in curves. Look-ahead fixations target the whole visible road, but locations with a smaller eccentricity relative to the guiding fixations were more commonly fixated than those with a high eccentricity. Experienced drivers allocated more time to look-ahead fixations compared to novices. Cognitive load may negatively affect trajectory planning by interfering with look-ahead fixations. Based on the results, the role of trajectory planning in the control of steering is discussed. The results are consistent with a hierarchical model of driving behaviour, where trajectory planning supplies the intended path for the level of the online control of steering.Arkikokemuksenkin perusteella on selvää että autolla ajettaessa on paras katsoa minne on menossa. Esimerkiksi jos alkaa lukea viestejä kännykästä ajaessaan, voi yhtäkkiä havahtua siihen että on auto ajautumassa pois omalta kaistalta. Ajonaikaista silmänliikemittausta hyödyntämällä voidaan kuitenkin saada arkikokemusta tarkempaa tietoa siitä mihin kuljettajan katse kohdistuu. Aikaisemmat tutkimukset ovat osoittaneet että katseen suunta ennakoi auton suunnanmuutoksia muutamalla sekunnilla. Selvimmin tämä on nähtävissä mutkissa, jossa katseen siirtyminen mutkan suuntaan edeltää auton kääntymistä. Tätä katsekäyttäytymistä voi nimittää ohjaaviksi katseiksi. Kirjallisuudessa on esitetty useita erilaisia visuaalisen informaation kognitiivista prosessointia kuvaavia ohjausmalleja, jotka selittävät ohjaavien katseiden suuntautumista. Ohjausmallien mukaan kuljettaja seuraa katseellaan ohjauspisteitä tieympäristössä. Ohjausmallit kuvaavat kuinka ohjauspisteiden sijaintiin perustuva visuaalinen informaatio muutetaan ohjausliikkeiksi. Nämä ohjausmallit ovat kuitenkin yksinkertaistuksia ihmisen toiminnasta joka on pohjimmiltaan erittäin monimutkaista. Ne kuvaavat ikään kuin mekaanisesti sen, miten ohjausliikkeet tuotetaan visuaalisesta informaatiosta. Näitä ohjausmalleja voikin kutsua tämän takia online-ohjausmalleiksi. On kuitenkin selvää että ihmiset myös suunnittelevat ajolinjan, jota he online-ohjausmalleilla seuraavat. Tässä suunnitelmassa otetaan huomioon niin tieympäristö, muut tienkäyttäjät kuin tilanteeseen sopiva nopeuskin. Väitöskirjassani olen tarkastellut niin sanottuja etenemistä ennakoivia katseita, jotka todennäköisesti liittyvät ajolinjan suunnitteluun. Etenemistä ennakoivissa katseissa kuljettaja siirtää nopeasti katseensa pois online-ohjauksesta, kauemmas kohti tulevaa ajolinjaa. Ohjaavat ja ennakoivat katseet eroavat toisistaan selvästi lähestyttäessä tai ajettaessa mutkissa, koska silloin tuleva ajolinja voi olla hyvinkin paljon sivummalla verrattuna auton sen hetkiseen kulkusuuntaan. Hyvä esimerkki etenemistä ennakoivasta katseesta on se, jos juuri ennen mutkaa vilkaisee peltoaukean yli kohti mutkan päätepistettä. Väitöskirjassani olen kehittänyt menetelmiä joilla ohjaavat ja etenemistä ennakoivat katseet voidaan erotella silmänliikemittausdatasta. Olen tarkastellut mihin etenemistä ennakoivat katseet kohdistuvat, ja kuinka ajokokemus ja ajonaikainen kognitiivinen kuormitus (jollaista esimerkiksi kännykkään puhuttaessa on) vaikuttavat. Tulokset viittaavat siihen, että etenemistä ennakoivat katseita käytetään muodostamaan suunnitelmaa tulevasta ajolinjasta. Kokemattomuus ja kognitiivinen kuormitus vähensivät ennakoivia katseita, mikä viittaa siihen että tällöin ajolinjan suunnittelu on vähäisempää. Tulokset ovat tuottaneet perustutkimuksellista ymmärrystä liikkumisen visuaalisesta ohjauksesta. Tuloksilla on kuitenkin myös sovellettavuutta: Ensinnäkin, tulokset täydentävät ymmärrystä siitä mitkä mekanismit voivat olla kokemattomien ja esimerkiksi kännykkään puhuvien kuljettajien onnettomuuksien taustalla. Toisekseen, autoteknologia on matkalla kohti itsestään ajavia autoja. Ennen kuin perusperheautokin kulkee itsekseen Helsingistä Ivaloon marraskuisessa räntä- ja lumisateessa, autoihin kehitetään esimerkiksi kuljettajan katsetta seuraavia järjestelmiä, jotka voivat varoittaa jos kuljettaja ei tarkkaile ympäristöään riittävästi. Tällöin on hyvä ymmärtää että osa sivuun suuntautuvista katseista on osa ajamisen ohjausta eikä osoitus kuljettajan keskittymisestä johonkin muuhun

Anticipatory eye movements when approaching a curve on a rural road depend on working memory load

Peer reviewe

Child passengers and driver culpability in fatal crashes by driver gender

PMID: 26507116AbstractObjective: Studies based on accident statistics generally suggest that the presence of a passenger reduces adult drivers' accident risk. However, passengers have been reported to be a source of distraction in a remarkable portion of distraction related crashes. Although the effect of passengers on driving performance has been studied extensively, few studies have focused on how a child passenger affects the driver. A child in a car is a potential distractor for parents, especially for mothers of small children who often suffer from sleep deficit. The aim of this study was to examine how the presence of child passengers of different ages is associated with a higher driver culpability, which was expected due to child related distraction and fatigue. Methods: The analysis was based on the comprehensive data of fatal crashes studied in-depth by multidisciplinary road accident investigation teams in Finland during 1988–2012. Teams determine the primary party who had the most crucial effect on the origin of the event. We define the primary party as culpable and the others involved as non-culpable drivers. The culpability rate was defined as the percentage of culpable drivers and rates were compared for drivers with a child/teen passenger aged 0–17 year (N = 348), with an adult passenger without children (N = 324) and when driving alone (N = 579), grouped by child age and driver gender. Drivers with specific risk-related behavior (substantial speeding, driving when intoxicated, unbelted, or without license) were excluded from the analyses, in order to make the drivers with and without children comparable. Only drivers 26–47 years old were included, representing parents with children 0–9 years of age. Results: Male drivers were less often culpable with 0–17 year old passengers in the car than alone or with adults. This was not the case with female drivers. The gender difference in culpability was most marked with small children of 0–4 years. Female drivers' culpability rate with a 0–4 year old child passenger was higher but male drivers' lower as compared to drivers without passengers or with only adult passenger. Conclusion: The results indicate that female drivers are at higher risk of crashes than male drivers when driving with small children. Further research is needed to replicate this finding and to determine causal mechanisms.Peer reviewe

A computational driver model to predict driver control at unsignalised intersections

The interaction between a cyclist and a driver at unsignalized intersection remains a risky situation which may result in a collision with severe consequences, especially for the cyclist. Crash data show that the number of cyclist fatalities at unsignalized intersections has been stable the last years, indicating that more efforts should be given to improve safety in this specific scenario. Safety systems can help drivers avoid collisions with cyclists.\ua0 However, systems addressing this conflict scenario are difficult to design, not only because of the technical aspects (e.g., sensor, or control limitations) but because those systems need to predict how drivers will or would control their car to be effective. A handful of studies focused on describing driver behaviour in this traffic scenario, but no computational model that can predict driver control can be found in the literature. The present study presents a driver model based on a biofidelic human sensorimotor control modelling framework predicting driver control in this traffic scenario. Two visual cues were implemented: 1) optical longitudinal looming, and 2) projected post-encroachment time between the bike and the car. The model was optimized using test-track data in which participants were asked to drive through an intersection where a cyclist would cross their travel path. The performances of the model were evaluated by comparing the simulated driver control process with the observed controls for each trial using a leave-one-out crossvalidation process. The results showed that the model performed rather well by reproducing similar braking controls, and kinematics, compared to the observations. The extent to which the model could be used by safety systems’ threat-assessment algorithms was discussed. Future research to improve the model performances was suggested

Effects of an active visuomotor steering task on covert attention

In complex dynamic tasks such as driving it is essential to be aware of potentially important targets in peripheral vision. While eye tracking methods in various driving tasks have provided much information about drivers’ gaze strategies, these methods only inform about overt attention and provide limited grounds to assess hypotheses concerning covert attention. We adapted the Posner cue paradigm to a dynamic steering task in a driving simulator. The participants were instructed to report the presence of peripheral targets while their gaze was fixed to the road. We aimed to see whether and how the active steering task and complex visual stimulus might affect directing covert attention to the visual periphery. In a control condition, the detection task was performed without a visual scene and active steering. Detection performance in bends was better in the control task compared to corresponding performance in the steering task, indicating that active steering and the complex visual scene affected the ability to distribute covert attention. Lower targets were discriminated slower than targets at the level of the fixation circle in both conditions. We did not observe higher discriminability for on-road targets. The results may be accounted for by either bottom-up optic flow biasing of attention, or top-down saccade planning.Peer reviewe

Evaluating bicyclists’ risk perception using video clips: Comparison of frequent and infrequent city cyclists

Abstract Hazard and risk perception has been studied extensively among car drivers, and their link to crash involvement is established. Bicyclists, in particular, are vulnerable road users. Better understanding of their risk and hazard perception could help to improve their traffic safety. In this study, we investigated the risk perception of bicyclists in a city environment. Two groups of bicyclists were compared: 19 frequent and 19 infrequent bicyclists. Participants were shown video clips taken with a camera attached to the handlebar of a bicycle, and they were asked to continuously indicate with a slider how much caution the situation needed. The frequent cyclists had more frequent rises in the caution estimate, which suggest that they anticipated or detected more hazards than infrequent cyclists. This is in line with the classical hazard perception results, which link the car driving experience to faster and more accurate hazard perception. The overall level or caution was not directly related to the rise event rate or bicycling frequency. Those cyclists who reported typically cycling faster than others showed elevated overall level of caution on sidewalks compared with others, but there was no difference on bike paths.Hazard and risk perception has been studied extensively among car drivers, and their link to crash involvement is established. Bicyclists, in particular, are vulnerable road users. Better understanding of their risk and hazard perception could help to improve their traffic safety. In this study, we investigated the risk perception of bicyclists in a city environment. Two groups of bicyclists were compared: 19 frequent and 19 infrequent bicyclists. Participants were shown video clips taken with a camera attached to the handlebar of a bicycle, and they were asked to continuously indicate with a slider how much caution the situation needed. The frequent cyclists had more frequent rises in the caution estimate, which suggest that they anticipated or detected more hazards than infrequent cyclists. This is in line with the classical hazard perception results, which link the car driving experience to faster and more accurate hazard perception. The overall level or caution was not directly related to the rise event rate or bicycling frequency. Those cyclists who reported typically cycling faster than others showed elevated overall level of caution on sidewalks compared with others, but there was no difference on bike paths. (C) 2015 Elsevier Ltd. All rights reserved.Peer reviewe

Situated accomplishment of well-being in interaction: a conversation-analytic study of instructor intervention, driver reflection and displays of (dis)comfort in voluntary post-licence training

Private car travel constitutes an important means of transportation for senior members of society: having access to a car is often key to gaining access to various services and activities. Among the retired population, many couples have adopted practices that promote driving performed by the husband while demoting driving performed by the wife. If the husband then ceases driving, the wife may be faced with the dilemma of having a need to drive, owning a car and holding a valid driving licence – but not having the skills and confidence to drive. Post-licence training offers a solution to such situations in providing a safe, supportive environment to practice. Nevertheless, as part of any training, drivers have to deal with various settings and situations, some of which may be emotionally intense and have adverse effects on the willingness to drive. This study takes a look at one such case, where an instructor treats a trainee driver’s conduct so problematic as to stop the dual-control car at a junction. The study examines how the participants attempt to establish, maintain and update their mutual understanding of the unfolding situation, how they produce and respond to displays of emotion, (dis)comfort in particular, and how those displays contribute to the course of the training, the ultimate goal of which is independent driving. The study thus explores how participants accomplish well-being in situ in interaction with one another. The study employs ethnomethodological conversation analysis and draws on video recordings from on-road post-licence training for older women drivers

Game-based situation awareness training for child and adult cyclists

Safe cycling requires situation awareness (SA), which is the basis for recognizing and anticipating hazards. Children have poorer SA than adults, which may put them at risk. This study investigates whether cyclists’ SA can be trained with a video- based learning game. The effect of executive working memory on SA was also studied. Thirty-six children (9–10 years) and 22 adults (21–48 years) played the game. The game had 30 video clips filmed from a cyclist’s perspective. Each clip was suddenly masked and two or three locations were presented. The player’s task was to choose locations with a potential hazard and feedback was given for their answers. Working memory capacity (WMC) was tested with a counting span task. Children’s and adults’ performance improved while playing the game, which suggests that playing the game trains SA. Adults performed better than children, and they also glanced at hazards more while the video was playing. Children expectedly had a lower WMC than adults, but WMC did not predict performance within the groups. This indicates that SA does not depend on WMC when passively viewing videos.Peer reviewe