Visual attention while driving: sequences of eye fixations made by experienced and novice drivers

Eye fixations were recorded while novice and experienced drivers drove along three types of roads (rural, suburban and dual-carriageway). An analysis of the content of those fixations was performed in order to identify differences in the scanpaths that can be associated with skill acquisition and that can indicate a sensitivity to road type. This analysis itemized the part of the visual scene that was inspected with each fixation, and identified what the driver looked at as a function of what they had looked at previously. Single-fixation, two-fixation, and three-fixation patterns of eye-movements were identified. Differences in sequences of fixations were found between novice and experienced drivers on the three types of roads, with experienced drivers showing greater sensitivity overall, and with some stereotypical transitions in the visual attention of the novices. A number of individual sequences were identified, including a roadway preview pattern (alternating fixations between near and far views of the road ahead), and patterns involving mirror inspections that varied according to the road type.     

Visual attention while driving: sequences of eye fixations made by experienced and novice drivers

Eye fixations were recorded while novice and experienced drivers drove along three types of roads (rural, suburban and dual-carriageway). An analysis of the content of those fixations was performed in order to identify differences in the scanpaths that can be associated with skill acquisition and that can indicate a sensitivity to road type. This analysis itemized the part of the visual scene that was inspected with each fixation, and identified what the driver looked at as a function of what they had looked at previously. Single-fixation, two-fixation, and three-fixation patterns of eye-movements were identified. Differences in sequences of fixations were found between novice and experienced drivers on the three types of roads, with experienced drivers showing greater sensitivity overall, and with some stereotypical transitions in the visual attention of the novices. A number of individual sequences were identified, including a roadway preview pattern (alternating fixations between near and far views of the road ahead), and patterns involving mirror inspections that varied according to the road type.     

Visual attention and the transition from novice to advanced driver

Inexperienced drivers are particularly vulnerable to road traffic accidents, and inattention emerges as a factor in these accidents. What do these drivers attend to and how can their observation skills be developed? When drivers scan the road around them, differences are observed as function of driving experience and training, with experienced drivers increasing their visual scanning on roadways of increasing complexity. Trained police drivers showed this effect of increased scanning even more than experienced drivers. This suggests that the driver's understanding of the task develops with experience, such that roads that demand increased monitoring (e.g. interweaving traffic on a multi-lane highway) receive more extensive scanning than roads that are simpler (e.g. light traffic on a straight rural road). Novice drivers do not show this sensitivity to road complexity, suggesting that they fail to attend to potential dangers involving the behaviour of other road users. Encouragingly, a simple training intervention can increase the visual scanning of novices.     

A simulated study on the effects of information volume on traffic signs, viewing strategies and sign familiarity upon driver''s visual search performance

A two-stage simulation experiment was conducted to investigate the effect of information volume on traffic regulatory/road direction signs, drivers’ viewing strategies and sign familiarity on performance in visual search. In Stage I experiment, the amount of information on a total of 187 traffic regulatory and 1272 road direction signs was calculated and divided into five information levels using cluster analysis. In Stage II experiment, 24 subjects participated in a 2 (familiarity)×5 (information volume level)×2 (viewing strategy) mixed factorial experiment. Each subject was required to perform a visual search task and a question-and-answer (Q&A) task. Visual search time and number of correct responses collected serve as the objective dependent variables. Subjective workload related to time stress and visual effort was gathered through a modified three-point rating. Results show that information volume on traffic signs had significant impact on drivers’ visual search performance. Generally, the greater the amount of information, the slower the drivers in visual search are. However, while drivers had the highest accuracy rate in remembering purely pictorial traffic signs, these signs within the smallest information volume level required a relatively longer search time. Different viewing strategies also led to different performances. The back-and-forth strategy yielded better search performance than the fixed strategy. Subjective workload evaluation indicates that drivers with less sign familiarity will be under greater time/visual pressures. Guidelines for designing for traffic signs or in-vehicle signing systems are provided.

Relevance to industry

This study calculated the amount of information on traffic signs and compared the effects of different information volume on drivers’ visual search performance. The results can provide guidelines for traffic sign designers to help decide on the presentation format for in-vehicle signing information systems.     

Obituary. Ted Megaw

Within the theoretical framework of control motivation, the effect of transient motivational variations (extrinsic to driving) on decision making in a simulated driving task was investigated. Young male drivers (mean age= 20.5 years), who were either novices or more experienced, participated in two experiments. In the first study (n = 45), the participants firstly carried out a reasoning task, extrinsic to driving, in which they randomly either failed (high control motivation), succeeded (low control motivation) or made aesthetic judgments with no evaluation in terms of success or failure (control group). Later, the participants had to decide whether to modify the given speed of a same vehicle for 38 driving situations presented in slide form. These situations were sorted into four categories according to the presence or absence of other road users and the presence or absence of an intersection. Compared with the control group, the participants of the failure group decide to make more speed changes as a function of the categories of driving situations and choose to make greater decelerations. Success leads the novices to discriminate less between the different categories of driving situations when making speed changes. A second study (n = 60) assessed whether high control motivation systematically induces a safer decision. The same driving task as in the first study was introduced by an instruction which made salient a representation of driving as being either cooperative or competitive. Whatever the instruction, the same results were found with the more experienced drivers: previous failure induces greater deceleration than success does. The opposite is observed for novices when driving was presented as a competitive activity, especially for intersection situations with no visible users. This discussion presents the usefulness of control motivation for understanding the drivers' regulation of their motivational states (allocation of attentional resources) and their representation of risk.     

Selective searching while driving: the role of experience in hazard detection and general surveillance

Novice drivers have been found in previous studies to display a limited search of the immediate environment, relative to experienced drivers, when manoeuvring on a dual-carriageway road. The present study investigated whether this reduction in the variance of search along the horizontal plane was a product of less frequent glancing in the car's mirrors. Novice and experienced drivers were observed as they made lane changes in relatively unobstructed conditions and when they needed to move into a lane already occupied by traffic. Novice drivers were found to rely more than experienced drivers upon their internal mirror, even when the lane-changing manoeuvre required information about traffic in the lane best reflected in the external, door-mounted mirror. Novices did increase their use of the external mirror in response to driving needs, suggesting that they did have an awareness of the situation that required inter-weaving with traffic in their destination lane. Their reliance upon the internal mirror may be a product of a habit acquired specifically for the driver licensing examination, in which exaggerated inspection of the internal mirror is regarded as being desirable.     

The effect of communicational signals on drivers' subjective appraisal and visual attention during interactive driving scenarios

Communicational signals (e.g. lights and horns) are imperative for on-road interaction between drivers. The aim of the present study was to explore how these signals affect drivers' subjective appraisal and visual attention, and how drivers decode the signals from other vehicles within a variety of interactive contexts. Twenty-five male participants (20 valid samples, ranging from 21 to 29 years of age) were recruited to watch film clips of pre-designed interactive scenarios involving common vehicle signals in a full-view simulator (i.e. including road view and mirror views). Participants' attitudes towards the interacting vehicle's behaviours, emotional responses, fixation metrics, and decoded meanings were recorded and analysed. The majority of tested signals, with the exception of the horn used in the behind vehicles, significantly improved drivers' attitudes and pleasure. All signals significantly increased emotional arousal, as well as the total fixation time and mean fixation duration on the interacting vehicle. When the interacting vehicle was visible in mirrors, the signal usage significantly increased the fixation frequency towards it. Meanwhile, a significant decrease in total fixation time and mean fixation duration on the road was reported. The results also demonstrated that the decoded signal contained several meanings simultaneously depending on both the signal type and its interactive context. This study quantified the communication process via vehicular signals under typical situations involving other vehicles, and also suggested new ideas on how to establish more advanced communication between drivers.     

Cognitive analysis of experts’ and novices’ concept mapping processes: An eye tracking study

The goal of this study was to explore how designated experts (subject experts with extensive experience in science education and concept mapping) and novices (pre-service teachers) establish concept map (CM) development processes while considering their cognitive processes. Two experiments were conducted in which eye-tracking, written, and verbal data were collected from 29 novices and 6 subject matter experts. The results showed that despite some similar strategies, novices and experts followed different patterns during the CM development process. Both experts and novices embraced deductive reasoning and preferred hierarchical type CMs. Additional points studied during the process include filling out requested information in different orders, branch construction pattern, content richness and progress pattern. Furthermore, eye behavior patterns also differed among experts and novices. Expert participants differed from novices in all eye behavior metrics (fixation count, fixation and visit duration for specific actions). Novices’ fixation count (FC) numbers were higher than the experts’ during the entire process and in specific periods. In conclusion, these pattern differences affect the CM development process directly. Considering the patterns revealed in the study may help instructors guide learners more adequately and effectively.     

Eye movements of younger and older drivers.

This 2-part study focuses on eye movements to explain driving-related visual performance in younger and older persons. In the first task, participants' eye movements were monitored as they viewed a traffic scene image with a numeric overlay and visually located the numbers in their sequential order. The results showed that older participants had significantly longer search episodes than younger participants, and that the visual search of older adults was characterized by more fixations and shorter saccades, although the average fixation durations remained the same. In the second task, participants viewed pictures of traffic scenes photographed from the driver's perspective. Their task was to assume the role of the driver and regard the image accordingly. Results in the second task showed that older participants allocated a larger percentage of their visual scan time to a small subset of areas in the image, whereas younger participants scanned the images more evenly. Also, older participants revisited the same areas and younger participants did not. The results suggest how aging might affect the efficacy of visual information processing. Potential applications of this research include training older drivers for a more effective visual search, and providing older drivers with redundant information in case some information is missed.     

Divided attention in experienced young and older drivers: lane tracking and visual analysis in a dynamic driving simulator.

A simulated driving task that required the simultaneous execution of two continuous visual tasks was administered to 12 healthy young (mean age 26.1 years) and 12 healthy older (mean age 64.4 years) experienced and currently active drivers. The first task was a compensatory lane-tracking task involving a three-dimensional road display. The second task was a timed, self-paced visual analysis task involving either a vocal or manual binary response to dot patterns projected within the road display. Using adaptive tasks, single-task difficulty was individually adjusted for each subject. To control for individual differences in attention allocation strategy, the dual task was performed according to three different sets of instructions based on the relative importance of each task. Compared with young adults, older adults showed a significantly decreased ability to divide attention. This effect was apparent in lane tracking and in the accuracy of visual analysis. The impairment of divided attention was less pronounced in the vocal condition than in the manual one. This suggests that difficulty in integrating responses may be an important determinant of poor dual-task performance in old age.     

Impact of experience when using the Rapid Upper Limb Assessment to assess postural risk in children using information and communication technologies

The Rapid Upper Limb Assessment (RULA) is an observation-based screening tool that has been used to assess postural risks of children in school settings. Studies using eye-tracking technology suggest that visual search strategies are influenced by experience in the task performed. This study investigated if experience in postural risk assessments contributed to differences in outcome scores on the RULA and the visual search strategies utilized. While wearing an eye-tracker, 16 student occupational therapists and 16 experienced occupational therapists used the RULA to assess 11 video scenarios of a child using different mobile information and communication technologies (ICT) in the home environment. No significant differences in RULA outcome scores, and no conclusive differences in visual search strategies between groups were found. RULA can be used as a screening tool for postural risks following a short training session regardless of the assessor's experience in postural risk assessments.     

Utilization of Visual Information Perception Characteristics to Improve Classification Accuracy of Driver’s Visual Search Intention for Intelligent Vehicle

Understanding and predicting a driver’s behaviors in a vehicle is a prospective function embedded in a smart car. Beyond the patterns of observable behaviors, driver’s intention could be identified based on goal-driven behaviors. A computational model to classify driver intention in visual search which is finding a target with one’s eyes as moving selective attention across a search field, could improve the level of intelligence that a smart car could demonstrate. To develop a computational cognitive that explains the underlying cognitive process and reproduces drivers’ behaviors, particular parameters in human cognitive process should be specified. In this study, 2 issues are considered as influential factors on a driver’s eye movements: a driver’s visual information processing characteristics (VIPCs) and the purpose of visual search. To assess an individual’s VIPC, 4 psychological experiments—Donders’s reaction time, mental rotation, signal detection, and Stroop experiments—were utilized. Upon applying k-means clustering method, 114 drivers were divided into 9 driver groups. To investigate the influence of task goal on a driver’s eye movement, driving simulation was conducted to collect a driver’s eye movement data under the given purpose of visual search (perceptual and cognitive tasks). The empirical data showed that there were significant differences in a driver’s oculomotor behavior, such as response time, average fixation time, and average glance duration between the driver groups and the purposes of visual search. The effectiveness of using VIPC for grouping drivers was tested with task goal classification model by comparing the models’ performance when drivers were grouped by typical demographic data such as gender. Results show that grouping based on VIPC improves accuracy and stability of prediction of the model on a driver’s intention underlying visual search behaviors. This study would benefit future studies focusing on personalization and adaptive interfaces in the development of smart car.     

Identification of human implicit visual search intention based on eye movement and pupillary analysis

We propose a novel approach for the identification of human implicit visual search intention based on eye movement patterns and pupillary analysis, in general, as well as pupil size, gradient of pupil size variation, fixation length and fixation count corresponding to areas of interest, and fixation count corresponding to non-areas of interest, in particular. The proposed model identifies human implicit visual search intention as task-free visual browsing or task-oriented visual search. Task-oriented visual search is further identified as task-oriented visual search intent generation, task-oriented visual search intent maintenance, or task-oriented visual search intent disappearance. During a visual search, measurement of the pupillary response is greatly influenced by external factors such the intensity and size of the visual stimulus. To alleviate the effects of external factors, we propose a robust baseline model that can accurately measure the pupillary response. Graphical representation of the measured parameter values shows significant differences among the different intent conditions, which can then be used as features for identification. By using the eye movement patterns and pupillary analysis, we can detect the transitions between different implicit intentions—task-free visual browsing intent to task-oriented visual search intent and task-oriented visual search intent maintenance to task-oriented visual search intent disappearance—using a hierarchical support vector machine. In the proposed model, the hierarchical support vector machine is able to identify the transitions between different intent conditions with greater than 90 % accuracy.     

More perspectives from Australia

A simulation study of the effects of visual lobe shape and search strategy on search performance is reported. Using a homogeneous pattern search task that did not dictate eye fixation movements (as in reading), three basic categories of strategy and two lobe shapes were tested. Random strategies with controlled overlap of lobe areas, representing various degrees of memory, were found to produce better performance (faster search times with equal or better detection rates) than either a completely random strategy or systematic strategies with various degrees of controlled visual lobe area overlap. The controlled overlap random strategies were far better able to compensate for non-optimum interfixation distances and distortion of visual lobe shape than systematic strategies.     

A comparison of visual ability and its importance awareness between novice and experienced drivers

The visual ability factors of peripheral perception, visual reaction and visual pursuit ability are important for safe driving. Thus, this study explored the influence of driving experience on these visual ability factors. Sixty-five drivers, including novice and experienced drivers, participated in this study. The visual ability levels of the three factors were measured by the Vienna Test System. In addition, driver's awareness of the three factors' importance for safe driving was measured by questionnaire items. Results showed that out of the three factors, drivers' peripheral perception ability was correlated significantly with their driving experience. Experienced drivers had higher peripheral perception ability than that of novice drivers. In addition, compared with novice drivers, experienced drivers believed that peripheral perception was more important whereas visual reaction was less important. It is suggested that higher attention should be paid to peripheral perception in driving training and novice drivers should increase their importance awareness for this factor.     

Effect of driving experience on drivers' decoding process of roadway interpersonal communication

Sixty-three participants (32 novice, 31 experienced drivers) evaluated meanings of road users' signals in 24 traffic situations such as blinkers, headlights, hazard lamps and hand gestures. The traffic scenes were projected with a slide projector in a laboratory. Confidence in answers was also evaluated by using a five-point scale. The signals were classified into three categories: Formal Device-based Signal (Formal Signal), Informal Device-based Signal (Informal Signal), and Informal Gesture-based Signal (Everyday Signal). The total comprehension scores demonstrated that experienced drivers could understand the signals better than novice drivers. There was a large difference in the comprehension scores for Informal Signal between experienced and novice drivers. Novice drivers could understand Formal Signal and Everyday Signal better than Informal Signal. Similar results were also obtained in the confidence scores. Experienced drivers were more confident in their answers than novice drivers. An effect of gender was found in the scores of confidence. The discussion focuses on how driver's skill in interpersonal communication on roads develops in real traffic situations.     

Effect of driving experience on drivers' decoding process of roadway interpersonal communication

Sixty-three participants (32 novice, 31 experienced drivers) evaluated meanings of road users' signals in 24 traffic situations such as blinkers, headlights, hazard lamps and hand gestures. The traffic scenes were projected with a slide projector in a laboratory. Confidence in answers was also evaluated by using a five-point scale. The signals were classified into three categories: Formal Device-based Signal (Formal Signal), Informal Device-based Signal (Informal Signal), and Informal Gesture-based Signal (Everyday Signal). The total comprehension scores demonstrated that experienced drivers could understand the signals better than novice drivers. There was a large difference in the comprehension scores for Informal Signal between experienced and novice drivers. Novice drivers could understand Formal Signal and Everyday Signal better than Informal Signal. Similar results were also obtained in the confidence scores. Experienced drivers were more confident in their answers than novice drivers. An effect of gender was found in the scores of confidence. The discussion focuses on how driver's skill in interpersonal communication on roads develops in real traffic situations.     

Effect of drivers' age and push button locations on visual time off road, steering wheel deviation and safety perception

The study examined the effects of manual control locations on two groups of randomly selected young and old drivers in relation to visual time off road, steering wheel deviation and safety perception. Measures of visual time off road, steering wheel deviations and safety perception were performed with young and old drivers during real traffic. The results showed an effect of both driver's age and button location on the dependent variables. Older drivers spent longer visual time off road when pushing the buttons and had larger steering wheel deviations. Moreover, the greater the eccentricity between the normal line of sight and the button locations, the longer the visual time off road and the larger the steering wheel deviations. No interaction effect between button location and age was found with regard to visual time off road. Button location had an effect on perceived safety: the further away from the normal line of sight the lower the rating.     

Differences between experts and novices in the monitoring of automated systems

In the future of aviation, operators will have to work with highly automated systems. This necessitates operators monitoring appropriately (OMA). Psychophysiological studies support the idea that eye movements offer an appropriate means for measuring the acquisition of visual information. A normative model for adequate monitoring behaviour was developed and eye movement parameters were defined to identify OMA. The normative model was validated by eye tracking studies with airline pilots and air traffic controllers. The present eye-tracking study focused on differences in monitoring behaviour between experts and novices. Results from 21 experts (experienced pilots and air traffic controllers) and 33 novices (applicants for jobs in aviation) are reported. Significant differences in monitoring behaviour between experts and novices were found. Experts allocate their attention more efficiently. Learning from experts’ monitoring of automated processes will be helpful in learning how to select successful trainees and provide them with appropriate training.     

An investigation of train driver visual strategies

Train driving is primarily a visual task; train drivers are required to monitor the dynamic scene visually both outside and inside the train cab. Poor performance on this visual task may lead to errors, such as signals passed at danger. It is therefore important to understand the visual strategies that train drivers employ when monitoring and searching the visual scene for key items, such as signals. Prior to this investigation, a pilot study had already been carried out using an eye tracking technique to investigate train drivers’ visual behaviour and to collect data on driver monitoring of the visual environment, Groeger et al. (2003) Pilot study of train drivers’ eye movements, University of Surrey. However, a larger set of data was needed in order to understand more fully train driver visual behaviour and strategies. In light of this need, the Transport Research Laboratory produced a methodology for the assessment of UK train driver visual strategies, on behalf of the Rail Safety and Standards Board and applied this methodology to conduct a large-scale trial. The study collected a wealth of data on train drivers’ visual behaviour with the aim of providing a greater understanding of the strategies adopted. The corneal dark-eye tracking system chosen for these trials tracks human visual search and scanning patterns, and was fitted to 86 drivers whilst driving in-service trains. Data collected include the duration and frequency of glances made towards different elements of the visual scene. In addition, the train drivers were interviewed after driving the routes, to try and understand the thought processes behind the behaviour observed. Statistical analysis of over 600 signal approaches was conducted. This analysis revealed that signal aspect, preceding signal aspect, signal type and signal complexity are important factors, which affect the visual behaviour of train drivers. Train driver interview data revealed that driver expectation also plays a significant role in train driving. The findings of this study have implications for the rail industry in terms of infrastructure design, design of the driving task and driver training. However, train driving is extremely complex and the data from this study only begin to describe and explain train driver visual strategies in the specific context of signal approaches. This study has provided a wealth of data and further analysis of it is needed to investigate the role of other factors and the complex relationships between factors during signal approaches and other driving situations systematically. Finally, there are important aspects of visual behaviour that cannot be examined using these data or this method. Investigation of other aspects of visual behaviour, such as peripheral vision, will require other methods such as simulation.