Helen Petrie

The relationship between accessibility and usability of websites

Accessibility and usability are well established concepts for user interfaces and websites. Usability is precisely defined, but there are different approaches to accessibility. In addition, different possible relationships could exist between problems encountered by disabled and non-disabled users, yet little empirical data have been gathered on this question. Guidelines for accessibility and usability of websites provide ratings of the importance of problems for users, yet little empirical data have been gathered to validate these ratings. A study investigated the accessibility of two websites with 6 disabled (blind) and 6 non-disabled (sighted) people. Problems encountered by the two groups comprised two intersecting sets, with approximately 15% overlap. For one of the two websites, blind people rated problems significantly more severely than sighted people. There was high agreement between participants as to the severity of problems, and agreement between participants and researchers. However, there was no significant agreement between either participants or researchers and the importance/priority ratings provided by accessibility and usability guidelines. Practical and theoretical implications of these results are discussed.

Haptic virtual reality for blind computer users

This paper describes a series of studies involving a haptic device which can display virtual textures and 3-D objects. The device has potential for simulating real world objects and assisting in the navigation of virtual environments. Three experiments investigated: (a) whether previous results from experiments using real textures could be replicated using virtual textures; (b) whether participants perceived virtual objects to have the intended size and angle; and (c) whether simulated real objects could be recognised. In all the experiments differences in perception by blind and sighted people were also explored. The results have implications for the future design of VEs in that it cannot be assumed that virtual textures and objects will feel to the user as the designer intends. However, they do show that a haptic interface has considerable potential for blind computer users.

Guidelines are only half of the story: accessibility problems encountered by blind users on the web

This paper describes an empirical study of the problems encountered by 32 blind users on the Web. Task-based user evaluations were undertaken on 16 websites, yielding 1383 instances of user problems. The results showed that only 50.4% of the problems encountered by users were covered by Success Criteria in the Web Content Accessibility Guidelines 2.0 (WCAG 2.0). For user problems that were covered by WCAG 2.0, 16.7% of websites implemented techniques recommended in WCAG 2.0 but the techniques did not solve the problems. These results show that few developers are implementing the current version of WCAG, and even when the guidelines are implemented on websites there is little indication that people with disabilities will encounter fewer problems. The paper closes by discussing the implications of this study for future research and practice. In particular, it discusses the need to move away from a problem-based approach towards a design principle approach for web accessibility.

Remote usability evaluations With disabled people

Finding participants for evaluations with specific demographics can be a problem for usability and user experience specialists. In particular, finding participants with disabilities is especially problematic, yet testing with disabled people is becoming increasingly important. Two case studies are presented that explore using asynchronous remote evaluation techniques with disabled participants. These show that while quantitative data are comparable, the amount and richness of qualitative data are not likely to be comparable. The implications for formative and summative evaluations are discussed and a set of principles for local and remote evaluations with disabled users is presented.

MOBIC: Designing a Travel Aid for Blind and Elderly People

This paper presents the research for the development of a new travel aid to increase the independent mobility of blind and elderly travellers. This aid will build on the technologies of geographical information systems (GIS) and the Global Positioning System (GPS). The MOBIC Travel Aid (MOTA) consists of two interrelated components : the MOBIC Pre-journey System (MOPS) to assist users in planning journeys and the MOBIC Outdoor System (MooDs) to execute these plans by providing users with orientation and navigation assistance during journeys. The MOBIC travel aid is complementary to primary mobility aids such as the long cane or guide dog. Results of a study of user requirements are presented and their implications for the initial design of the system are discussed.

Forcing standardization or accommodating diversity?: a framework for applying the WCAG in the real world

Since 1999 the W3Cs Web Content Accessibility Guidelines (WCAG) have provided a solid basis for implementation of accessible Web design. However it is argued that in the context of evaluation and policymaking, inappropriate reference to the WCAG may lead to serious practical difficulties in implementation and monitoring of an effective accessibility policy. There is a pressing need for a framework that guides appropriate application of the WCAG in a holistic way, taking into account the diversity -- or homogeneity -- of factors such as context of use, audience and audience capability, and access environment. In particular, the current promotion of W3C technologies at the expense of widely used and accessible proprietary technologies may be problematic, as is the apparent reliance of the WCAG on compliant browsing technology.In this paper, a holistic application of the WCAG is proposed by the authors, whereby the context of the Web resource in question and other factors surrounding its use are used to shape an approach to accessible design. Its potential application in a real world environment is discussed.

Contextual web accessibility - maximizing the benefit of accessibility guidelines

We argue that while work to optimize the accessibility of the World Wide Web through the publication and dissemination of a range of guidelines is of great importance, there is also the need for a more holistic approach to maximizing the role of the Web in enabling disabled people to access information, services and experiences. The persistently disappointingly low levels of usability of Web content for disabled people indicates that focusing on the adoption of accessibility guidelines by content authors, tool developers and policy makers is not sufficient for a truly inclusive Web. This approach fails to acknowledge the role of the Web as an enabler in a broader context and may stifle creative use of Web content and experiences to enhance social inclusion.Using e-learning as an example, and describing current metadata developments, we present a framework that will guide Web authors and policy makers in addressing accessibility at a higher level, by defining the context in which a Web resource will be used and considering how best existing or new alternatives may be combined to enhance the accessibility of the information and services provided by the site in question. We demonstrate how guidelines such as those produced by the W3Cs Web Accessibility Initiative have a role to play within this wider context, along with metadata and user profiling initiatives.

Tension? what tension?: website accessibility and visual design

It is a widespread belief amongst web designers and implementers that sites that are accessible to users with disabilities must by necessity be uninteresting and simple, particularly visually uninteresting -- plain, vanilla sites. It is tempting to believe that such sites do not pose interesting challenges to web designers and implementers. However, it is our contention that this belief is profoundly misguided. Certainly, a very plain, visually simple site is quite likely to be accessible (although this is not guaranteed). However, the opposite is not necessarily the case -- sites can be visually interesting and sophisticated and still highly accessible. Visual and interesting web design is largely orthogonal to accessibility and these two factors should not be seen as being in opposition to each other. Accessibility should rather be viewed as another challenge to designers and implementers, along with creating a site that is usable, interesting and appealing to mainstream users.

Auditory navigation in hyperspace: design and evaluation of a non-visual hypermedia system for blind users

This paper presents the design and evaluation of a hypermedia system for blind users, making use of a non-visual interface, non-speech sounds, three input devices, and a 37-node hypermedia module. The important components of an effective auditory interface are discussed, together with the design of the auditory interface to hypermedia material. The evaluation is described, which was conducted over several weeks, and used a range of complementary objective and subjective measures to assess usability, performance and user preferences. The findings from evaluations with 9 visually impaired student participants are presented. The results from this research can be applied to the design and evaluation of other non-visual hypermedia systems, such as auditory WWW browsers and digital talking books.

Development of dialogue systems for a mobility aid for blind people: initial design and usability testing

This paper presents a new travel aid to increase the independent mobility of blind and elderly travellers. This aid builds on the technologies of geographical information systems (GIS) and the Global Positioning System (GPS). The MoBIC Travel Aid (MoTA) consists of two interrelated components: the MoBIC Pre-journey System (MoPS) to assist users in planning journeys and the MoBIC Outdoor System (MoODS) to execute these plans by providing users with orientation and navigation assistance during journeys. The MoBIC travel aid is complementary to primary mobility aids such as the long cane or guide dog. Results of a study of user requirements, the user interface designs, and the first field trial, currently being conducted in Berlin, are presented.