Web interaction environments : characterising Web accessibility at the large

Tese de doutoramento, Informática (Engenharia Informática), Universidade de Lisboa, Faculdade de Ciências, 2012Accessibility quality on the Web is essential for providing a good Web experience to people with disabilities. The existence of virtual ramps aid these users grasping and interacting withWeb content, just like the experience of those who are unimpaired. However, more often than not, Web pages impose accessibility barriers, usually centred on the unavailability of tailored content to specific perceptual abilities (e.g., textual description of images, enabling grasping information with assistive technologies), as well as on proper HTML structural elements that adequate the semantics of a Web page. When evaluating the accessibility quality of Web pages, the resulting analysis is often focused on a small sample set (e.g., a single Web page or a selection of pages from a Web site). While this kind of analysis gets the gist of accessibility quality, it misses the big picture on the overall accessibility quality of the Web. This thesis addresses the challenge of observing accessibility phenomena on the Web, through the experimental evaluation of large collections of Web pages. This resulted on new findings about the accessibility quality of the Web, such as its correlation with HTML element count, and the erroneous perception of accessibility quality by developers. Small-scale experiments have been verified also at large scale, such as the correlation between the usage of HTML templates and accessibility quality. Based on the challenges raised by the experimental evaluation, this thesis proposes a novel approach for large scale Web accessibility evaluation based on Linked Data, as well as the establishment of metrics to assess the truthfulness and coverage of automated evaluation methods.A qualidade da acessibilidade é um factor crucial para as pessoas com deficiências terem uma boa experiência de interacção com a Web.A qualidade da acessibilidade é um factor crucial para as pessoas com deficiências terem uma boa experiência de interacção com a Web. A existência de rampas virtuais ajuda estas pessoas a compreender e interagir com conteúdos Web, a par do que o utilizador comum já experiencia. Porém, a maioria das páginas Web ainda contêm barreiras à acessibilidade. Estas barreiras centram-se normalmente na indisponibilidade de conteúdos perceptíveis por diferentes tipos de capacidades (e.g., descrições textuais de imagens), bem como no uso incorrecto de elementos HTML de acordo com a semântica de uma página Web. Nos dias de hoje, a avaliação da qualidade de acessibilidade de páginas Web é ainda efectuada em pequena escala (e.g., uma página Web ou, no melhor caso, um conjunto de páginas representativas de um sítio Web). Apesar deste tipo de avaliações resultarem na compreensão de alguns fenómenos do estado da acessibilidade na Web, ainda não se sabe qual o seu impacto em larga escala. Esta tese discute os principais desafios na observação da acessibilidade da Web, tendo por base um conjunto de avaliações experimentais de colecções de grande dimensão de páginas Web. Destes estudos destacam-se as seguintes contribuições e resultados:a diferença drástica na interpretação dos avisos resultantes de avaliações de acessibilidade Web: um dos resultados principais da avaliação experimental em larga escala destaca a diferença na interpretação dos avisos (warnings) da aplicação de técnicas da norma WCAG, onde a interpretação optimista (i.e., a visão da maioria dos criadores de páginas Web) se distancia amplamente da interpretação conservadora (onde os avisos são interpretados como erros); a correlação entre a qualidade da acessibilidade de uma página Web e a sua complexidade: este mesmo estudo de larga escala revelou uma correlação entre a complexidade de uma página Web (no que diz respeito ao número de elementos HTML que contém) e a qualidade da acessibilidade. Quanto menor a complexidade de uma página Web, mais certa se torna a alta qualidade da acessibilidade dessa página; o benefício do uso de templates e sistemas de gestão de conteúdos na melhoria da acessibilidade de páginas Web: em ambos os estudos experimentais de acessibilidade foi detectada uma correlação entre a qualidade de acessibilidade das páginas Web e o uso de templates e sistemas de gestão de conteúdo. Esta propriedade foi verificada quer em pequena escala (sobre uma colecção de páginas Web da Wikipedia), quer em larga escala; o incumprimento das regras mais elementares e mais conhecidas da acessibilidade: estes estudos experimentais permitiram também verificar que, apesar de toda a envagelização e educação sobre as questões de acessibilidade na Web, a maioria das regras de acessibilidade são incessantemente quebradas pela maioria das páginas Web.Esta problemática verifica-se, em particular, nas regras de cumprimento de acessibilidade mais conhecidas, tal como por exemplo a disponibilidade de textos alternativos a conteúdos multimédia. Com base nestas experiências e resultados, esta tese apresenta um novo modelo de estudo da acessibilidade na Web, tendo por base o ciclo de estudos da Web em larga escala. Deste modelo resultaram as seguintes contribuições: um modelo para a avaliação distribuída de acessibilidade Web, baseado em propriedades tecnológicas e topológicas: foi concebido um modelo de avaliação de acessibilidade Web que permite a concepção de sistemas de avaliação com base em propriedades tecnológicas e topológicas. Este modelo possibilita, entre outras características, o estudo da cobertura de plataformas e avaliadores de acessibilidade, bem como da sua aplicação em larga escala; uma extensão às linguagens e modelos EARL e Linked Data, bem como um conjunto de definições para extrair informação destes: este modelo de avaliação de acessibilidade Web foi sustentado também pela sua concretização em linguagens e modelos já existentes para o estudo de acessibilidade (EARL) e da Web em larga escala (Linked Data), permitindo assim a sua validação; definição dos limites da avaliação de acessibilidade Web: por fim, este modelo de avaliação de acessibilidade permitiu também delinear uma metodologia de meta-avaliação da acessibilidade, na qual se poderão enquadrar as propriedades dos avaliadores de acessibilidade existentes. Todas estas contribuições resultaram também num conjunto de publicações científicas, das quais se destacam: Rui Lopes and Luís Carriço, A Web Science Perspective of Web Accessibility, in submission for the ACM Transactions on Accessible Computing (TACCESS), ACM, 2011; Rui Lopes and Luís Carriço, Macroscopic Characterisations of Web Accessibility, New Review of Hypermedia and Multimedia – Special Issue on Web Accessibility. Taylor & Francis, 2010; Rui Lopes, Karel Van Isacker and Luís Carriço, Redefining Assumptions: Accessibility and Its Stakeholders, The 12th International Conference on Computers Helping People with Special Needs (ICCHP), Vienna, Austria, 14-16 July 2010; Rui Lopes, Daniel Gomes and Luís Carriço, Web Not For All: A Large Scale Study of Web Accessibility, W4A: 7th ACM International Cross-Disciplinary Conference on Web Accessibility, Raleigh, North Carolina, USA, 26-27 April 2010; Rui Lopes, Konstantinos Votis, Luís Carriço, Dimitrios Tzovaras, and Spiridon Likothanassis, The Semantics of Personalised Web Accessibility Assessment, 25th Annual ACM Symposium on Applied Computing (SAC), Sierre, Switzerland, 22-26 March, 2010 Konstantinos Votis, Rui Lopes, Dimitrios Tzovaras, Luís Carriço and Spiridon Likothanassis, A Semantic Accessibility Assessment Environment for Design and Development for the Web, HCI International 2009 (HCII 2009), San Diego, California, USA, 19-24 July 2009 Rui Lopes and Luís Carriço, On the Gap Between Automated and In-Vivo Evaluations of Web Accessibility, HCI International 2009 (HCII 2009), San Diego, California, USA, 19-24 July 2009; Rui Lopes, Konstantinos Votis, Luís Carriço, Spiridon Likothanassis and Dimitrios Tzovaras, Towards the Universal Semantic Assessment of Accessibility, 24th Annual ACM Symposium on Applied Computing (SAC),Waikiki Beach, Honolulu, Hawaii, USA, 8-12 March 2009; Rui Lopes and Luís Carriço, Querying Web Accessibility Knowledge from Web Graphs, Handbook of Research on Social Dimensions of Semantic Technologies, IGI Global, 2009; Rui Lopes, Konstantinos Votis, Luís Carriço, Spiridon Likothanassis and Dimitrios Tzovaras, A Service Oriented Ontological Framework for the Semantic Validation of Web Accessibility, Handbook of Research on Social Dimensions of Semantic Technologies, IGI Global, 2009; Rui Lopes and Luís Carriço, On the Credibility of Wikipedia: an Accessibility Perspective, Second Workshop on Information Credibility on the Web (WICOW 2008), Napa Valley, California, USA, 2008; Rui Lopes, Luís Carriço, A Model for Universal Usability on the Web, WSW 2008: Web Science Workshop, Beijing, China, 22 April 2008; Rui Lopes, Luís Carriço, The Impact of Accessibility Assessment in Macro Scale Universal Usability Studies of the Web, W4A: 5th ACM International Cross-Disciplinary Conference on Web Accessibility, Beijing, China, 21-22 April 2008. Best paper award; Rui Lopes, Luís Carriço, Modelling Web Accessibility for Rich Document Production, Journal on Access Services 6 (1-2), Routledge, Taylor & Francis Group, 2009; Rui Lopes, Luís Carriço, Leveraging Rich Accessible Documents on the Web, W4A: 4th ACM International Cross-Disciplinary Conference on Web Accessibility, Banff, Canada, 7-8 May 2007.Fundação para a Ciência e a Tecnologia (FCT, SFRH/BD/29150/2006

An Information Foraging Theory Perspective on Tools for Debugging, Refactoring, and Reuse Tasks

Theories of human behavior are an important but largely untapped resource for software engineering research. They facilitate understanding of human developers’ needs and activities, and thus can serve as a valuable resource to researchers designing software engineering tools. Furthermore, theories abstract beyond specific methods and tools to fundamental principles that can be applied to new situations. Toward filling this gap, we investigate the applicability and utility of Information Foraging Theory (IFT) for understanding information-intensive software engineering tasks, drawing upon literature in three areas: debugging, refactoring, and reuse. In particular, we focus on software engineering tools that aim to support information-intensive activities, that is, activities in which developers spend time seeking information. Regarding applicability, we consider whether and how the mathematical equations within IFT can be used to explain why certain existing tools have proven empirically successful at helping software engineers. Regarding utility, we applied an IFT perspective to identify recurring design patterns in these successful tools, and consider what opportunities for future research are revealed by our IFT perspective.Keywords: Programming Environments, Software maintenance, Integrated environments, Information foraging, Interactive environments, Programmer workbench, Human Factors, DesignKeywords: Programming Environments, Software maintenance, Integrated environments, Information foraging, Interactive environments, Programmer workbench, Human Factors, Desig

Enriching Web Information Scent for Blind Users

Link annotation with the accessibility level of the target Web page is an adaptive navigation support technique aimed at increasing blind users' orientation in Web sites. In this work, the accessibility level of a page is measured by exploiting data from evaluation reports produced by two automatic assessment tools. These tools support evaluation of accessibility and usability guideline-sets. As a result, links are annotated with a score that indicates the conformance of the target Web page to blind user accessibility and usability guidelines. A user test with 16 users was conducted in order to observe the strategies they followed when links were annotated with these scores. With annotated links, the navigation paradigm changed from sequential to browsing randomly through the subset of those links with high scores. Even if there was not a general agreement on the correspondence between scores and user perception of accessibility, users found annotations helpful when browsing through links related to a given topic

On The Human Factors Impact of Polyglot Programming on Programmer Productivity

Polyglot programming is a common practice in modern software development. This practice is often considered useful to create software by allowing developers to use whichever language they consider most well suited for the different parts of their software. Despite this ubiquity of polyglot programming there is no empirical research into how this practice affects software developers and their productivity. In this dissertation, after reviewing the state of the art in programming language and linguistic research pertaining to the topic, this matter is investigated by way of two empirical studies with 109 and 171 participants solving programming tasks. Based on the findings, the design of a data management library, a common use-case for polyglot programming, is proposed broadly and then applied specifically to the language Quorum as a case study. The review of previous studies finds that there is a pattern of productivity gain that can be explained by the occurrence of type annotations in programming, which gives insight into how programmers comprehend code. Study results show that there is a significant improvement of programmer productivity when programmers are using polyglot programming in an embedded context (partial eta squared = 0.039) and that less experienced programmers do better in a group with more frequent, but less severe, switches, while more experienced developers perform better with less frequent but more complete switches between languages. A study on language switches on a file level shows that file level programming language switching has a clear negative impact on programmer productivity (partial eta squared = 0.059) and is most likely caused by the increased occurrence of errors when switching

Designing Search User Interfaces for Visually Impaired Searchers: A User-centred Approach

PhDThe Web has been a blessing for visually impaired users as with the help of assistive technologies such as screen readers, they can access previously inaccessible information independently. However, for screen reader users, web-based information seeking can still be challenging as web pages are mainly designed for visual interaction. This affects visually impaired users’ perception of theWeb as an information space as well as their experience of search interfaces. The aim of this thesis is therefore to consider visually impaired users’ information seeking behaviour, abilities and interactions via screen readers in the design of a search interface to support complex information seeking. We first conduct a review of how visually impaired users navigate the Web using screen readers. We highlight the strategies employed, the challenges encountered and the solutions to enhance web navigation through screen readers. We then investigate the information seeking behaviour of visually impaired users on the Web through an observational study and we compare this behaviour to that of sighted users to examine the impact of screen reader interaction on the information seeking process. To engage visually impaired users in the design process, we propose and evaluate a novel participatory approach based on a narrative scenario and a dialogue-led interaction to verify user requirements and to brainstorm design ideas. The development of the search interface is informed by the requirements gathered from the observational study and is supported through the inclusion of visually impaired users in the design process. We implement and evaluate the proposed search interface with novel features to support visually impaired users for complex information seeking. This thesis shows that considerations for information seeking behaviour and users’ abilities and mode of interaction contribute significantly to the design of search user interfaces to ensure that interface components are accessible as well as usable