Designing Mobile Friendly CAPTCHAs: An Exploratory Study.

CAPTCHAs (Completely Automated Public Turing Test to Tell Computers and Humans Apart) are one of the most widely used authentication mechanisms that help to prevent online service abuse. With the advent of mobile computing, mobile devices such as smartphones and tablets have become the primary way people access the Internet. As a result, increasing attention has been paid to designing CAPTCHAs that are mobile friendly. Although such CAPTCHAs generally show their advantages over traditional ones, it is still unclear what the best practices are for designing a CAPTCHA scheme that is easy to use on mobile devices. In this paper, we present an exploratory study that focuses on developing a more holistic view of usability issues with interactive CAPTCHAs to inform design guidance. This is done through investigating the usability performance of seven mobile friendly CAPTCHA schemes representing five different CAPTCHA types

Adapting heuristic evaluation for use in information visualization

Orientador: Celmar Guimarães da SilvaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de TecnologiaResumo: A Avaliação Heurística é um método clássico de avaliação de interfaces de um sistema interativo na área de Interação Humano-Computador. Pesquisadores e desenvolvedores de software usam esta técnica com frequência, já que ela é rápida, barata e fácil de ser executada. Porém, para usar a técnica em outros sistemas de domínio específico, é necessário criar um novo conjunto de heurística capaz de identificar os problemas dessa área. Em Visualização de Informação (InfoVis), a técnica é utilizada com o conjunto proposto por Nielsen, que possui apenas heurísticas de usabilidade, deixando de cobrir outros conceitos importantes de InfoVis. Na literatura, estão presentes conjuntos de recomendações que cobrem os conceitos de InfoVis, entretanto, muitas destas recomendações não são apresentadas como heurísticas, ou então são restritas a um determinado contexto. Desta forma, este trabalho apresenta um método para criar um conjunto de heurísticas de InfoVis, para ser usado na Avaliação Heurística. O método agrupa as heurísticas e recomendações encontradas na literatura, e cria novas heurísticas com base em cada grupo formado. Assim, um novo conjunto com 15 heurísticas genéricas foi criado, a partir de um conjunto com 62 heurísticas e recomendações e, posteriormente, avaliado. A hipótese é que o novo conjunto irá auxiliar os avaliadores a considerar um conjunto mais amplo de conceitos de visualização durante a Avaliação Heurística com, possivelmente, menos esforço cognitivo, quando comparado com a aplicação direta das 62 heurísticas e recomendaçõesAbstract: Heuristic evaluation technique is a classical evaluation method of user interface in Human-Computer Interaction area. Researchers and software developers broadly use it, given that it is fast, cheap and easy to use. Using it in other system of specific domains demands creating a new heuristic set able to identify common problems of these areas. Information Visualization (InfoVis) researchers commonly use this technique with the original usability heuristic set proposed by Nielsen, which does not cover many relevant aspects of InfoVis. InfoVis literature presents sets of guidelines that cover InfoVis concepts, but it does not present most of them as heuristics, or they cover much specific context. This work presents a method to define a set of InfoVis heuristics for use in Heuristic Evaluation. The method clusters heuristics and guidelines that was found in the literature, and creates a new heuristic based on each group. Thus, a new set of 15 generic heuristics was created, from a set of 62 heuristics and guidelines, and after it was evaluated. The new set will help evaluators to consider a broad set of visualization aspects during Heuristic Evaluation, with possibly less cognitive effort, when compared with a direct application of the 62 heuristics and guidelinesMestradoSistemas de Informação e ComunicaçãoMestre em TecnologiaCAPE

The trade-off between usability and security in the context of eGovernment

Electronic government (e-government) implements a wide range of online services that are supported by the latest information communication technology (ICT) and accessible by devices that have great mobility in delivering services to citizens. The ongoing rapid advancements of these portable devices make user centred service design more challenging and complex as citizens’ demands, needs and preferences are varied and become more complicated over time. Also, existing research reveals that e-government still experiencing the challenge of creating better users’ interaction in terms of accessing online information and using electronic services. Among a variety of reasons for this challenge, usability and security have been recognised in previous research to be the main reasons in users’ decisions to use e-government services and need to be investigated. In addition, to the limited attention given to users’ preferences and human-centred design guidelines, creates more unusable and unsecure services. This research attempts to investigate the trade-off between usability and security from a user perspective, in order to understand how users, perceive the usability and security of e-government services by focusing on three elements of e-government. The research investigates three aspects related to e-government services, when new service being introduced, new devices being integrated, and new technology adopted. Each research study examines one of these aspects to explore how users or citizens perceive them in term of usability and security. By conducting these three studies, the researcher seeks a clear and comprehensive picture of users’ attitudes, opinions and preferences, and a rich insight into users’ needs. This research tries to explain user requirements for new services, devices and technology implemented in e-government settings, in terms of usability and security features. A mixed methods strategy, using quantitative and qualitative methods, is used capture users’ experiences and attitudes to the use of e-government services in terms of usability and security. These methods help us understand the three, related, aspects of e-government through the eyes of the participants rather than in categories predetermined by the researcher. Therefore, a questionnaire survey is used, with open-ended questions, and focus group research. A broader landscape view on the present state of users’ perception and attitudes about the trade-off between usability and security was studied and reported according to the findings from the three studies. The three studies findings and the literature review help the researcher to propose a set of usability and security guidelines to improve e-government services, which in turn would improve e-services usability and security aspects. The proposed set of guidelines complement the general usability guidelines or heuristics by considering user concerns and insights. The author presented some recommendation based on the findings of each study. These guidelines can be useful to guide designers to develop a usable and more secure e-services that match with users’ requirements

Heuristics for the evaluation of captchas on smartphones

Captchas are used as a security mechanism on the web to distinguish human users from automated programs. However, existing captchas are not well-adapted to mobile devices and may lead users to abandon tasks. Although Web developers have many available captchas, they lack the tools to evaluate if these captchas are suitable for their mobile site. In this paper, we present domain specific usability heuristics for evaluating captchas on smartphones. To assess effectiveness, we compared our proposed heuristics against Nielsen's during evaluations of four captcha schemes on smartphones. The custom heuristics revealed more major problems and more detailed feedback on the problems than Nielsen's.Ye