How people use presentation to search for a link: expanding the understanding of accessibility on the Web

It is well known that many Web pages are difficult to use for visually disabled people. Without access to a rich visual display, the intended structure and organisation of the page is obscured. To fully understand what is missing from the experience of visually disabled users, it is pertinent to ask how the presentation of Web pages on a standard display makes them easier for sighted people to use. This paper reports on an exploratory eye tracking study that addresses this issue by investigating how sighted readers use the presentation of the BBC News Web page to search for a link. The standard page presentation is compared with a “text-only” version, demonstrating both qualitatively and quantitatively that the removal of the intended presentation alters “reading” behaviours. The demonstration that the presentation of information assists task completion suggests that it should be re-introduced to non-visual presentations if the Web is to become more accessible. The conducted study also explored the extent to which algorithms that generate maps of what is perceptually salient on a page match the gaze data recorded in the eye tracking study. The correspondence between a page’s presentation, knowledge of what is visually salient, and how people use these features to complete a task might offer an opportunity to re-model a Web page to maximise access to its most important parts.

A novel strong tracking finite-difference extended Kalman filter for nonlinear eye tracking

Non-intrusive methods for eye tracking are important for many applications of vision-based human computer interaction. However, due to the high nonlinearity of eye motion, how to ensure the robustness of external interference and accuracy of eye tracking poses the primary obstacle to the integration of eye movements into todays’s interfaces. In this paper, we present a strong tracking finite-difference extended Kalman filter algorithm, aiming to overcome the difficulty in modeling nonlinear eye tracking. In filtering calculation, strong tracking factor is introduced to modify a priori covariance matrix and improve the accuracy of the filter. The filter uses finite-difference method to calculate partial derivatives of nonlinear functions for eye tracking. The latest experimental results show the validity of our method for eye tracking under realistic conditions. Supported by the National Natural Science Foundation of China (Grant No. 60572027), the Outstanding Young Researchers Foundation of Sichuan Province (Grant No. 03ZQ026-033), the Program for New Century Excellent Talents in University of China (Grant No. NCET-05-0794), and the Young Teacher Foundation of Mechanical School (Grant No. MYF0806)     

Attention to the model's face when learning from video modeling examples in adolescents with and without autism spectrum disorder

We investigated the effects of seeing the instructor's (i.e., the model's) face in video modeling examples on students' attention and their learning outcomes. Research with university students suggested that the model's face attracts students' attention away from what the model is doing, but this did not hamper learning. We aimed to investigate whether we would replicate this finding in adolescents (prevocational education) and to establish how adolescents with autism spectrum disorder, who have been found to look less at faces generally, would process video examples in which the model's face is visible. Results showed that typically developing adolescents who did see the model's face paid significantly less attention to the task area than typically developing adolescents who did not see the model's face. Adolescents with autism spectrum disorder paid less attention to the model's face and more to the task demonstration area than typically developing adolescents who saw the model's face. These differences in viewing behavior, however, did not affect learning outcomes. This study provides further evidence that seeing the model's face in video examples affects students' attention but not their learning outcomes.     

Usability of various dwell times for eye-gaze-based object selection with eye tracking

This study investigates the usability of various “dwell times” for selecting visual objects with eye-gaze-based input by means of eye tracking. Two experiments are described in which participants used eye-gaze-based input to select visual objects consisting of alphanumeric characters, dots, or visual icons. First, a preliminary experiment was designed to identify the range of dwell time durations suitable for eye-gaze-based object selection. Twelve participants were asked to evaluate, on a 7-point rating scale, how easily they could perform an object-selection task with a dwell time of 250, 500, 1000, or 2000 ms per object. The evaluations showed that a dwell time of 250 ms to around 1000 ms was rated as potentially useful for object selection with eye-gaze-based input. In the following main experiment, therefore, 30 participants used eye tracking to select object sequences from a display with a dwell time of 200, 400, 800, 1000 or 1200 ms per object. Object selection time, object selection success rate, the number of object selection corrections, and dwell time evaluations were obtained. The results showed that the total time necessary to select visual objects (object selection time) increased when dwell time increased, but longer dwell times resulted in a higher object-selection success rate and fewer object selection corrections. Furthermore, regardless of object type, eye-gaze-based object selection with dwell times of 200–800 ms was significantly slower for participants with glasses than for those without glasses. Most importantly, participant evaluations showed that a dwell time of 600 ms per object was easiest to use for eye-gaze-based selection of all three types of visual objects.     

PeepList: Adapting ex-post interaction with pervasive display content using eye tracking

Short intensive interactions with unfamiliar pervasive displays coerce users to perform cognitive operations with uncertainty and risk of not being able to access the information of relevance later. We developed a new way of interaction with pervasive displays by harnessing the eye tracking technology to extract information that is most likely relevant to the user. These extracted bits of important information are presented to the user and sorted according to their estimated importance—in the PeepList. The users can interact with the PeepList without explicit commands and they can access the customized PeepList ex-post in order to review information previously consumed from the pervasive display.We carried out a user study involving 16 participants to evaluate the contribution of PeepList to efficient pervasive display interaction. The tests revealed that the PeepList system is unobtrusive, accurate, and in particular it reduces the interaction times by 40% when complex tasks were presented to the participants. A feasible user model can be built in under 30 seconds in 50% of all interactions, and in one minute, a majority of all interactions (70%) lead to a useful user model. Experimental results show that eye tracking is a valuable real-time implicit source of information about what the user is searching for on a pervasive display and that it can be used for real-time user interface adaptation. This considerably improves the efficiency of obtaining and retaining required data.     

Width guidelines for rectangular objects with penetrable and impenetrable borders

Generally, selection times quicken when objects are placed against a display's edge. Experiment 1 investigated whether or not this continues to be true if the width of those objects, i.e. rectangular scrollbars, was manipulated. The results indicated that increasing width affected selection times for objects with penetrable borders, but not for those with impenetrable borders. A follow-up experiment examined whether or not selection times vary when participants selected very thin and wider scrollbars, each with impenetrable borders. The results indicated that width manipulations did not influence selection time, thus designers could use very thin objects with impenetrable borders without slowing selection time.     

万维网的链接结构分析及其应用综述

当今万维网的规模已经快速发展到包含大约80亿个网页和560亿个超链接．此外，对万维网的创建进行全局规划显然是不可能的．这些都对万维网的相关研究提出了挑战．另一方面，互联网环境下通过超链连接起来的网页，为人们的日常和商务用途提供了非常丰富的信息资源，但前提是必须掌握有效的办法来理解万维网．链接结构分析在万维网的很多研究领域起着越来越重要的作用．全面介绍了万维网链接分析方面的最新研究进展和应用情况，对链接分析在Web信息搜索、万维网潜在社区发现及万维网建模等方面的研究进展和实际应用进行了综述．     

s-HITSc: an improved model and algorithm for topic distillation on the Web

Topic distillation on the Web, namely, finding quality information sources related to a given query topic with hyperlink analysis, has been shown to be useful in Web IR. Based on the analysis of three deficiencies of classical topic distillation algorithm HITS, this paper presents an improved model and algorithm named s-HITSc. Given a query topic, the improved algorithm can model a neighborhood graph at site granularity, compute the relevance weights of the nodes to the topic with content analysis, and apply weighted I/O operations in its iterative hyperlink analysis. Theoretical analysis and experimental results show that s-HITSc can control topic drift and identify more reasonable and meaningful authority and hub sites on a given topic.

Outcomes for design and learning when teenagers with autism codesign a serious game: A pilot study

Digital educational games research tends to lack ecological validity by not adequately taking into account the views and perspectives of children and young people with autism spectrum disorders (ASD). This paper is a pilot study that explores and analyses an academic‐based educational game that was co‐designed with and for young people with ASD. The serious game aims to help the players learn Geography‐specific knowledge and integrates several strategic features so that users can collaborate together against the computer or compete against each other. The educational game was evaluated over 5 sessions by 3 peer teams from 2 different special educational institutions, involving a total of 6 students with ASD. The participants were positive about their enjoyment, motivation, and social engagement. The results showed that the players' level of competitiveness not only influenced the experience within the game but also the interaction within the peer teams. The game mechanisms did help the participants with ASD increase their knowledge in Geography content. The main conclusion is that there are considerable benefits of including children with ASD in the design process and future research should explore more fully on how their involvement can enhance curriculum‐based learning as well as social engagement within the classroom.     

A wide view auto‐stereoscopic 3D display with an eye‐tracking system for enhanced horizontal viewing position and viewing distance

This paper describes the development of auto‐stereoscopic three‐dimensional (3D) display with an eye‐tracking system for not only the X‐axis (right–left) and Y‐axis (up–down) plane directions but also the Z‐axis (forward–backward) direction. In the past, the eye‐tracking 3D system for the XY‐axes plane directions that we had developed had a narrow 3D viewing space in the Z‐axis direction because of occurrence of 3D crosstalk variation on screen. The 3D crosstalk variation on screen was occurred when the viewer's eye position moved back and forth along the Z‐axis direction. The reason was that the liquid crystal (LC) barrier pitch was fixed and the LC barrier was able to control the only barrier aperture position. To solve this problem, we developed the LC barrier that is able to control the barrier pitch as well as the barrier aperture position in real time, corresponding to the viewer's eye position. As a result, the 3D viewing space has achieved to expand up to 320–1016 mm from the display surface in the Z‐axis direction and within a range of ±267 mm in the X‐axis direction. In terms of the Y‐axis direction, the viewing space is not necessary to be considered, because of a stripe‐shaped parallax barrier.     

The benefits of integrated eye tracking with airborne image recorders in the flight deck: A rejected landing case study

Aircraft accident investigation has played a pivotal role in improving the safety of aviation. Advances in recorder technology, specifically Cockpit Voice Recorders (CVRs) and Flight Data Recorders (FDR) have made a huge contribution to the understanding of occurrences for accident investigators. However, even these recorders have limitations such as the evidence they provide about pilots' situation awareness or behaviours. Supplementing audio and data recordings with video has been discussed for many years and whilst there continues to be debate among regulators, operators, manufacturers and pilot unions, the International Civil Aviation Organization (ICAO) has mandated Airborne Image Recorders (AIR) from 2023. The purpose of installing such systems is to provide evidence of crew operational behaviours in terms of both human-human and human-computer interactions (HCI) on the flight deck. Video alone is unlikely to provide sufficient evidence for investigators. This study examines the additional value that eye-tracking technology may provide through the case study of an accident involving an Airbus A330-300 aircraft which experienced a rejected landing. Currently, the investigation of such events, where crew interaction with automation is critical to their situation awareness, relies heavily on interview data. Such data may be unavailable (in the case of serious injury) or unreliable (based on hindsight bias). By integrating eye tracking technology into an AIR, accident investigators will potentially gain a better understanding of pilots’ visual scan patterns across flight deck instrumentation. This has implications for flight deck and procedural design as well as training and simulation.     

考虑Web金融信息的上市企业财务危机预测模型研究

以往财务危机预测研究主要基于财务指标,而随着研究的深入,财务指标本身的局限性也日益凸显,如财务报表的滞后性及财务数据易于被操纵等,这影响了财务危机预测模型的性能。鉴于此,通过情感倾向值的计算,将Web金融信息文本有效地数值化,并将其作为预测指标变量用于财务危机预测,使用LIBSVM分别构建纯财务指标预测模型和引入Web金融信息指标变量后的混合指标预测模型,并对模型的预测结果进行了比较分析。混合指标预测模型在预测的有效性、稳定性和超前性上均好于纯财务指标预测模型。     

Cooperative tracking control for general linear multiagent systems with directed intermittent communications: An artificial delay approach

This paper investigates the consensus tracking problem for general linear multiagent systems on directed graph containing a spanning tree. For the considered linear systems, the consensus tracking aim cannot be achieved by using only memoryless static relative output feedbacks. Of particular interest is that both current and delayed relative output information of agents are required to achieve consensus. For the case of continuous communication among agents, an artificial delay output feedback control method is proposed. By utilizing the Taylor representation for the delayed signal with the remainder in the integral form, a delay‐dependent sufficient condition is presented to guarantee the exponential convergence of the global tracking error systems. For the intermittent case, the consensus tracking performance can still be guaranteed based on a multiple graph‐dependent Lyapunov functionals method. It is theoretically revealed that the time delay plays a key role in the exponential convergence of the closed‐loop systems, and the definite relationships among the time delay, network structure, communication rate, and consensus convergence rate are also provided. The effectiveness of the proposed control scheme is confirmed by numerical simulations.     

Nonlinear control with integral sliding properties for circular aerial robot trajectory tracking: Real‐time validation

A nonlinear control algorithm for tracking dynamic trajectories using an aerial vehicle is developed in this work. The control structure is designed using a sliding mode methodology, which contains integral sliding properties. The stability analysis of the closed‐loop system is proved using the Lyapunov formalism, ensuring convergence in a desired finite time and robustness toward unknown and external perturbations from the first time instant, even for high frequency disturbances. In addition, a dynamic trajectory is constructed with the translational dynamics of an aerial robot for autonomous take‐off, surveillance missions, and landing. This trajectory respects the constraints imposed by the vehicle characteristics, allowing free initial trajectory conditions. Simulation results demonstrate the good performance of the controller in closed‐loop system when a quadrotor follows the designed trajectory. In addition, flight tests are developed to validate the trajectory and the controller behavior in real time.     

The embodied Web: embodied Web‐services interaction with an umbrella for augmented city experiences

This paper introduces the embodied Web, a new design paradigm for mobile devices. The embodied Web aims to provide an interface using real‐world embodied interaction to provide a computer‐augmented reality that accesses web services. This platform regards embodied interaction at three levels: operational level, activity level and social level; and is implemented with a combination of sensor, actuator and network connectivities. The platform is developed as a complex of hardware, software and network services. The implementation takes an approach of modularization of hardware, software and web services. As a practical prototype of the embodied Web, the Internet Umbrella Pileus was developed and tested. In contrast to the small screens of mobile devices, Pileus has a big screen on the underside of the umbrella, and it is operated by embodied interaction, including motion sensing of the device and location sensing of walking activities. Photo‐sharing and 3D map navigation is provided on the umbrella to expand the user's activity area. These services are provided by API hookups with Flickr and Google Earth. Pileus has been iteratively developed from user observations, design observations and intuitions and prototype evaluations. The umbrella was tested in a large urban environment (the city of Tokyo). Copyright © 2008 John Wiley & Sons, Ltd.