UX Analysis

The expressway traffic sign information volume threshold and AGS position based on driving behaviour

Reasonable traffic signs are important for ensuring operation safety and efficiency of expressways. The overloaded information of the traffic signs and improper distance ahead of the signs present serious problems, for they may raise the driver's visual cognition burden, reduce expressway operation efficiency and cause potential safety hazards. This paper aims at developing design criteria of traffic sign information volume and reasonable AGS positions with regard to driving behavior and traffic safety. The relationship among driving behavior, traffic sign information and AGS positions has been studied based upon driving simulation tests in this paper. The information of traffic signs is processed and quantified with the method of information entropy under the framework of information theory. According to traffic flow theory and a mathematical model of vehicle lane change, AGS positions are analyzed and reasonable positions are recommended in relation to the operation conditions on multi-lane expressways. During the simulation tests, drivers aged 20-40 with 2-10 year driving experience were invited for the tests and asked to drive along the designed expressway scenes. The driver's visual behavior was monitored with an eye tracking system and data of driving behavior and the vehicle running tracks were also collected during the simulation tests. The relationship model between traffic sign information volume, AGS position and driving behavior parameters was developed as a result of further data mining, analysis and synthesis. Eventually, a multidimensional indicator of expressway sign information volume threshold has been proposed and reasonable AGS positions on multi-lane expressways are determined.

8 versions available

The reality of myoelectric prostheses: understanding what makes these devices difficult for some users to control

Users of myoelectric prostheses can often find them difficult to control. This can lead to passive-use of the device or total rejection, which can have detrimental effects on the contralateral limb due to overuse. Current clinically available prostheses are “open loop” systems, and although considerable effort has been focused on developing biofeedback to “close the loop,” there is evidence from laboratory-based studies that other factors, notably improving predictability of response, may be as, if not more, important. Interestingly, despite a large volume of research aimed at improving myoelectric prostheses, it is not currently known which aspect of clinically available systems has the greatest impact on overall functionality and everyday usage. A protocol has, therefore, been designed to assess electromyographic (EMG) skill of the user and predictability of the prosthesis response as significant parts of the control chain, and to relate these to functionality and everyday usage. Here, we present the protocol and results from early pilot work. A set of experiments has been developed. First, to characterize user skill in generating the required level of EMG signal, as well as the speed with which users are able to make the decision to activate the appropriate muscles. Second, to measure unpredictability introduced at the skin–electrode interface, in order to understand the effects of the socket-mounted electrode fit under different loads on the variability of time taken for the prosthetic hand to respond. To evaluate prosthesis user functionality, four different outcome measures are assessed. Using a simple upper limb functional task prosthesis users are assessed for (1) success of task completion, (2) task duration, (3) quality of movement, and (4) gaze behavior. To evaluate everyday usage away from the clinic, the symmetricity of their real-world arm use is assessed using activity monitoring. These methods will later be used to assess a prosthesis user cohort to establish the relative contribution of each control factor to the individual measures of functionality and everyday usage (using multiple regression models). The results will support future researchers, designers, and clinicians in concentrating their efforts on the area that will have the greatest impact on improving prosthesis use.

14 versions available

User expectations of everyday gaze interaction on smartglasses

Gaze tracking technology is increasingly seen as a viable and practical input modality in a variety of everyday contexts, such as interacting with computers, mobile devices, public displays and wearables (e.g. smartglasses). We conducted an exploratory study consisting of six focus group sessions to understand people's expectations towards everyday gaze interaction on smartglasses. Our results provide novel insights into the role of use-context and social conventions regarding gaze behavior in acceptance of gaze interaction, various social and personal issues that need to be considered while designing gaze-based applications and user preferences of various gaze-based interaction techniques. Our results have many practical design implications and serve towards human-centric design and development of everyday gaze interaction technologies.

7 versions available

Utilization of viewing aids for safe operations with excavators

Camera monitor systems (CMS) and mirrors are intended to support excavator operators’ understanding of the surrounding and help prevent accidents. However, little is known about visual information acquisition of operators of large construction machinery, especially during machine movements. In this field study, utilization of viewing aids and other information sources during rotating movements of excavators was investigated by means of eye-tracking and task observation. Results show that, while CMS monitors and left mirrors were used for many rotating movements, other information sources around the machine were also attended, such as the right frontolateral area and the area around the attachment. The article discusses implications for safety and machinery design, such as positioning of viewing aids.

6 versions available

Vision and gait in Parkinson’s disease: impact of cognition and response to visual cues

Gait impairment is a core feature of Parkinson’s disease (PD) which is difficult to treat due to its multi-factorial nature. Gait dysfunction in PD has been linked to cognitive and visual deficits through separate strands of research. However cognitive and visual functions likely interact (termed visuo-cognition) and have a combined impact on gait. Attempting to further understand the roles of cognition and vision in gait in PD was the motivation behind this thesis. The primary aim was therefore to investigate visuo-cognition and its role in gait in PD. Saccade frequency during gait represents the amount of visual sampling employed when walking and is a useful online behavioural measure of visuo-cognition. However, previous investigations have been limited by lack of robust methodologies, technology and outcome measures. A key objective was therefore to establish robust saccadic measurement with mobile eye-tracking technology in PD and older adult controls. My original contributions to knowledge were that a mobile eye-tracker can measure saccadic activity during gait in PD and controls, but with variable accuracy and reliability for certain characteristics. Cognitive and visual functions were significantly related in both PD and controls, with stronger association in PD. Saccade frequency during gait was significantly reduced in people with PD compared to controls, particularly under dual task. Impaired saccade frequency can be ameliorated with a visual cue; as such intervention significantly increased saccade frequency in PD and controls which was maintained under dual task. Saccade frequency during gait was independently associated with cognitive and visual functions in PD. A structured model demonstrated that visuo-cognitive dysfunction had an indirect effect on gait in PD, with a central role for attention in all relationships involved. The major conclusion from this thesis was that gait impairment in PD is influenced by visuo-cognitive dysfunction, with implication for poor mobility and falls risk.

3 versions available

Where do older pedestrians glance before deciding to cross a simulated two-lane road? A pedestrian simulator paradigm

Knowing where to older pedestrians allocate their glances before deciding to cross the road can contribute to understanding the causes that lead them to make bad road crossing decisions. Research on older drivers suggest that they are over involved in crashes that involve navigation through intersections mainly because they focused on their travel path and rarely on other areas in the scene from where a hazard might appear. Yet, it is less known how older pedestrians spread their attention on their expected travel path. Eleven older participants (over 65) and ten younger adults were asked to make a road crossing decision in a simulated environment, while wearing an eye-tracker. Results exemplify significant differences between the younger and older adults; the older adults, in comparison to the younger, spent more time focusing on the central area of the scene and even less so in the last five seconds before making the crossing decision. These findings are consistent with older drivers’ behavior at intersections, suggesting that older pedestrians might be overly focused on their travel path.

7 versions available

A protocol to examine vision and gait in Parkinson’s disease: impact of cognition and response to visual cues

Background: Cognitive and visual impairments are common in Parkinson’s disease (PD) and contribute to gait deficit and falls. To date, cognition and vision in gait in PD have been assessed separately. Impact of both functions (which we term ‘visuo-cognition’) on gait however is likely interactive and can be tested using visual sampling (specifically saccadic eye movements) to provide an online behavioural measure of performance. Although experiments using static paradigms show saccadic impairment in PD, few studies have quantified visual sampling during dynamic motor tasks such as gait. This article describes a protocol developed for testing visuo-cognition during gait in order to examine the: 1) independent roles of cognition and vision in gait in PD, 2) interaction between both functions, and 3) role of visuo-cognition in gait in PD. Methods: Two groups of older adults (≥50 years old) were recruited; non-demented people with PD (n=60) and age-matched controls (n=40). Participants attended one session and a sub-group (n=25) attended two further sessions in order to establish mobile eye-tracker reliability. Participants walked in a gait laboratory under different attentional (single and dual task), environmental (walk straight, through a door and turning), and cueing (no visual cues and visual cues) conditions. Visual sampling was recorded using synchronised mobile eye-tracker and electrooculography systems, and gait was measured using 3D motion analysis. Discussion: This exploratory study examined visuo-cognitive processes and their impact on gait in PD. Improved understanding of the influence of cognitive and visual functions on visual sampling during gait and gait in PD will assist in development of interventions to improve gait and reduce falls risk. This study will also help establish robust mobile eye-tracking methods in older adults and people with PD.

17 versions available

Adding depth: establishing 3D display fundamentals for automotive applications

The advent of 3D displays offers Human-Machine Interface (HMI) designers and engineers new opportunities to shape the user's experience of information within the vehicle. However, the application of 3D displays to the in-vehicle environment introduces a number of new parameters that must be carefully considered in order to optimise the user experience. In addition, there is potential for 3D displays to increase driver inattention, either through diverting the driver's attention away from the road or by increasing the time taken to assimilate information. Manufacturers must therefore take great care in establishing the ‘do’s and ‘don’t's of 3D interface design for the automotive context, providing a sound basis upon which HMI designers can innovate. This paper describes the approach and findings of a three-part investigation into the use of 3D displays in the instrument cluster of a road car, the overall aim of which was to define the boundaries of the 3D HMI design space. A total of 73 participants were engaged over three studies. Findings indicate that users can identify depth more quickly and accurately when rendered in 3D, indicating potential for future applications using the depth dimension to relay information. Image quality was found to degrade with increasing parallax and indications of a fatigue effect with continued exposure were found. Finally, a relationship between minimum 3D offset, parallax position and object type was identified.

3 versions available

Air Traffic Controller working position

This document is prepared by the National Aerospace Laboratory NLR and contains the research study for Esterline Control & Communication Systems to study the effects of display size on operator working experience. The goal of this research is to come to an independent assessment on the difference in perceived working experience of air traffic controllers in two different controller working positions: 1. Multiple display arrangement: Regular-sized (2K x 2K) controller working position with a primary radar control screen supported by one auxiliary display (i.e. multiple display arrangement); and 2. Single display arrangement: Large screen display with both radar and auxiliary information integrated into one screen (i.e. single display arrangement). NLR performed an experimental study in which six air traffic controllers experienced working with both working positions. The experiment was performed in a simulated operational setting; i.e. NLR’s air traffic control simulator NARSIM radar. Working experience was defined by measuring operator performance aspects such as workload, (eye) fatigue, situation awareness, usability, and task performance. The study results show that the perceived ATCO working experience in a multiple display arrangement is preferred over the experience in a single display arrangement. This is supported by the situation awareness findings that show that the situation awareness was higher in the multiple display arrangement than in the single display arrangement. It is also supported by the workload findings that show the trend that the workload was perceived lower in the multiple display arrangement than in the single display arrangement.

4 versions available

Analysing people’s movement in the built environment via space syntax, objective tracking and gaze data

In this paper we use analysis tools from Space Syntax and objective observation of the human behaviour, to understand the impact of landmarks in the walking patterns of users of spaces. Our case study was a large exterior public open space (University Campus), in which participants could walk freely and simultaneously be tracked by several sensors. We carried Space Syntax analysis for this space, and then collected Global Positioning System (GPS) tracking information and used a mobile eye-tracking device to acquire eye gaze information. The collected data allowed us to map and analyse each subject behaviour in the public space. A more specific analysis was done to four selected landmarks that, according to the Space Syntax analysis, were the ones with higher integration values. Results indicate that landmarks with such higher integration values show also a larger count of fixations and saccades of gaze interaction.

1 version available:

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