Elizabeth Crundall

Why do car drivers fail to give way to motorcycles at t-junctions?

Studies of accident statistics suggest that motorcyclists are particularly vulnerable to collisions with other vehicles which pull out of side roads onto a main carriageway, failing to give way to the approaching motorcycle. Why might this happen? The typical response of the car driver is that they looked in the appropriate direction but simply failed to see the motorcycle. To assess the visual skills of drivers in such scenarios we compared the behaviour of novice and experienced drivers to a group of dual drivers (with both car and motorcycle experience). Participants watched a series of video clips, displayed across three screens, depicting the approach to various t-junctions. On reaching the junction, participants had to decide when it was safe to pull out. Responses and eye movements were measured. The results confirmed that dual drivers had the safest responses at junctions, especially in the presence of conflicting motorcycles. On a range of visual measures both novice and experienced drivers appeared inferior to dual drivers, though for potentially different reasons. There were however no differences in the time it took all drivers to first fixate approaching motorcycles. Instead the differences appeared to be due to the amount of time spent looking at the approaching motorcycle. The experienced drivers had shorter gazes on motorcycles than cars, suggesting that they either process less salient motorcycles faster than cars, or that they terminated the gaze prematurely perhaps because they did not realise they were fixating a motorcycle. We argue that this is potential evidence for an oculomotor basis for Look But Fail To See errors.

Motorcycling experience and hazard perception

Studies of hazard perception skills in car drivers suggest that the ability to spot hazards improves with driving experience. Is this the case with motorcyclists? Sixty-one motorcyclists, split across three groups (novice, experienced and advanced riders) were tested on a hazard perception test containing video clips filmed from the perspective of a motorcyclist. Response times to hazards revealed that the advanced riders (who had completed an advanced riding course) were the fastest, and the experienced riders were the slowest to respond to hazards, with novice riders falling in-between. Advanced riders were also found to make more internal attributions regarding the causes of the hazards than novice riders (though on a general measure of Locus of Control there was no difference between groups). The results demonstrate a link between advanced training and motorcycling hazard perception skill, but raise important concerns about the effects of mere experience on rider safety. This challenges previous conceptions that simply extrapolated from our understanding of the hazard perception skills of car drivers to this particularly vulnerable group of road users.

Negotiating Left-Hand and Right-Hand Bends: A Motorcycle Simulator Study to Investigate Experiential and Behaviour Differences Across Rider Groups

Why do motorcyclists crash on bends? To address this question we examined the riding styles of three groups of motorcyclists on a motorcycle simulator. Novice, experienced and advanced motorcyclists navigated a series of combined left and right bends while their speed and lane position were recorded. Each rider encountered an unexpected hazard on both a left- and right-hand bend section. Upon seeing the hazards, all riders decreased their speed before steering to avoid the hazard. Experienced riders tended to follow more of a racing line through the bends, which resulted in them having to make the most severe changes to their position to avoid a collision. Advanced riders adopted the safest road positions, choosing a position which offered greater visibility through the bends. As a result, they did not need to alter their road position in response to the hazard. Novice riders adopted similar road positions to experienced riders on the left-hand bends, but their road positions were more similar to advanced riders on right-hand bends, suggesting that they were more aware of the risks associated with right bends. Novice riders also adopted a safer position on post-hazard bends whilst the experienced riders failed to alter their behaviour even though they had performed the greatest evasive manoeuvre in response to the hazards. Advanced riders did not need to alter their position as their approach to the bends was already optimal. The results suggest that non-advanced riders were more likely to choose an inappropriate lane position than an inappropriate speed when entering a bend. Furthermore, the findings support the theory that expertise is achieved as a result of relearning, with advanced training overriding ‘bad habits’ gained through experience alone.

A study of unidirectional swipe gestures on in-vehicle touch screens

Touch screens are increasingly used within modern vehicles, providing the potential for a range of gestures to facilitate interaction under divided attention conditions. This paper describes a study aiming to understand how drivers naturally make swipe gestures in a vehicle context when compared with a stationary setting. Twenty experienced drivers were requested to undertake a swipe gesture on a touch screen in a manner they felt was appropriate to execute a wide range of activate/deactivate, increase/decrease and next/previous tasks. All participants undertook the tasks when either driving within a right-hand drive, medium-fidelity simulator or whilst sitting stationary. Consensus emerged in the direction of swipes made for a relatively small number of increase/decrease and next/previous tasks, particularly related to playing music. The physical action of a swipe made in different directions was found to affect the length and speed of the gesture. Finally, swipes were typically made more slowly in the driving situation, reflecting the reduced resources available in this context and/or the handedness of the participants. Conclusions are drawn regarding the future design of swipe gestures for interacting with in-vehicle touch screens.

Developing Predictive Equations to Model the Visual Demand of In-Vehicle Touchscreen HMIs

ABSTRACT Touchscreen human–machine interfaces (HMIs) are commonly employed as the primary control interface and touch-point of vehicles. However, there has been very little theoretical work to model the demand associated with such devices in the automotive domain. Instead, touchscreen HMIs intended for deployment within vehicles tend to undergo time-consuming and expensive empirical testing and user trials, typically requiring fully functioning prototypes, test rigs, and extensive experimental protocols. While such testing is invaluable and must remain within the normal design/development cycle, there are clear benefits, both fiscal and practical, to the theoretical modeling of human performance. We describe the development of a preliminary model of human performance that makes a priori predictions of the visual demand (total glance time, number of glances, and mean glance duration) elicited by in-vehicle touchscreen HMI designs, when used concurrently with driving. The model incorporates information theoretic components based on Hick–Hyman Law decision/search time and Fitts’ Law pointing time and considers anticipation afforded by structuring and repeated exposure to an interface. Encouraging validation results, obtained by applying the model to a real-world prototype touchscreen HMI, suggest that it may provide an effective design and evaluation tool, capable of making valuable predictions regarding the limits of visual demand/performance associated with in-vehicle HMIs, much earlier in the design cycle than traditional design evaluation techniques. Further validation work is required to explore the behavior associated with more complex tasks requiring multiple screen interactions, as well as other HMI design elements and interaction techniques. Results are discussed in the context of facilitating the design of in-vehicle touchscreen HMI to minimize visual demand.

A driving simulator study to explore the effects of text size on the visual demand of in-vehicle displays☆

Modern vehicles increasingly utilise a large display within the centre console, often with touchscreen capability, to enable access to a wide range of driving and non-driving-related functionality. The text provided on such displays can vary considerably in size, yet little is known about the effects of different text dimensions on how drivers visually sample the interface while driving and the potential implications for driving performance and user acceptance. A study is described in which sixteen people drove motorway routes in a medium-fidelity simulator and were asked to read text of varying sizes (9 mm, 8 mm, 6.5 mm, 5 mm, or 4 mm) from a central in-vehicle display. Pseudo-text was used as a stimulus to ensure that participants scanned the text in a consistent fashion that was unaffected by comprehension. There was no evidence of an effect of text size on the total time spent glancing at the display, but significant differences arose regarding how glances were distributed. Specifically, larger text sizes were associated with a high number of relatively short glances, whereas smaller text led to a smaller number of long glances. No differences were found in driving performance measures (speed, lateral lane position). Drivers overwhelmingly preferred the ‘compromise’ text sizes (6.5 mm and 8 mm). Results are discussed in relation to the development of large touchscreens within vehicles.

The role of experience and advanced training on performance in a motorcycle simulator

Motorcyclists are over-represented in collision statistics. While many collisions may be the direct fault of another road user, a considerable number of fatalities and injuries are due to the actions of the rider. While increased riding experience may improve skills, advanced training courses may be required to evoke the safest riding behaviours. The current research assessed the impact of experience and advanced training on rider behaviour using a motorcycle simulator. Novice riders, experienced riders and riders with advanced training traversed a virtual world through varying speed limits and roadways of different curvature. Speed and lane position were monitored. In a comparison of 60 mph and 40 mph zones, advanced riders rode more slowly in the 40 mph zones, and had greater variation in lane position than the other two groups. In the 60 mph zones, both advanced and experienced riders had greater lane variation than novices. Across the whole ride, novices tended to position themselves closer to the kerb. In a second analysis across four classifications of curvature (straight, slight, medium, tight) advanced and experienced riders varied their lateral position more so than novices, though advanced riders had greater variation in lane position than even experienced riders in some conditions. The results suggest that experience and advanced training lead to changes in behaviour compared to novice riders which can be interpreted as having a potentially positive impact on road safety.

The impact of map orientation and generalisation on congestion decisions: a comparison of schematic-egocentric and topographic-allocentric maps

Map information for drivers is usually presented in an allocentric-topographic form (as with printed maps) or in an egocentric-schematic form (as with road signs). The advent of new variable message boards on UK motorways raises the possibility of presenting road maps to reflect congestion ahead. Should these maps be allocentric-topographic or egocentric-schematic? This was assessed in an eye tracking study, with participants viewing maps of a motorway network in order to identify whether any congestion was relevant to their intended route. The schematic-egocentric maps were responded to most accurately with shorter fixation durations suggesting easier processing. In particular, the drivers entrance and intended exit from the map were attended to more in the allocentric maps. Individual differences in mental rotation ability also seem to contribute to poor performance on allocentric maps. The results favour schematic-egocentric maps for roadside congestion information, but also provide theoretical insights into map-rotation and individual differences. Statement of Relevance: This study informs designers and policy makers about optimum representations of traffic congestion on roadside variable message signs and, furthermore, demonstrates that individual differences contribute to problems with processing certain sign types. Schematic-egocentric representations of a motorway network produced the best results, as noted in behavioural and eye movement measures.

Altering Speed Perception through the Subliminal Adaptation of Music within a Vehicle

We consider the potential for novel in-vehicle user-interfaces that alter speed perception at a subliminal level through the spatial adaption of music. In a fixed-base simulator, twenty-six participants drove on a motorway and were asked to maintain a speed of 70mph. At specific points, the speedometer was turned off. Music at a constant tempo was played throughout but periodically changed in balance from a 50:50 front:rear speaker split to a 25:75 ratio. Without the speedometer, participants drove significantly slower after the music had faded from the front to rear speakers (mean speed 71.5mph) compared to when no change occurred (mean speed 73.1mph). Post study interviews revealed that participants were not aware of alterations in the spatial positioning of the music. Such results suggest drivers naturally slowed when the music faded from front to rear speakers in an unconscious attempt to re-envelope themselves within the sound bubble.

'STISIM-drive' meets 'MotorcycleSim': using driving simulation software to develop a unique motorcycle simulator for rider behavior research

In order to compare groups of road users who have fundamentally different skills, attitudes and behaviours, one of the first in-depth motorcycle simulation studies of its kind was conducted. The project was developed using the innovative ‘MotorcycleSim’ simulator designed and built at the University of Nottingham. The simulator is a research tool to investigate aspects of motorcycle ergonomics and rider human factors and is the first of its kind in the world to incorporate ‘STI-SIM Drive’ software that allows motorcyclists to ride a full size motorcycle and interact with a virtual riding environment (VRE). To build a simulator that was both fit for the purpose of research and provided the desired levels of fidelity associated with real world riding, a user-centred design process was adopted from the outset (based in principles of ISO:13407).