Simon Harper

Bio: Simon Harper is an academic researcher from University of Manchester. The author has contributed to research in topics: Web page & Web accessibility. The author has an hindex of 32, co-authored 208 publications receiving 3386 citations.

Visual complexity and aesthetic perception of web pages

Abstract: The visual appearance of a Web page influences the way a user will interact with the page. Web page structural elements (such as text, tables, links, and images) and their characteristics (such as colour and size) are used to determine the visual presentation and complexity level of a Web page. We theorise that by understanding a user's visual and aesthetic perception of a Web page we can understand the cognitive effort required for interaction with that page. This paper describes an investigation into user perception of the visual complexity and aesthetic appearance of Web pages. Results show a strong and high correlation between users' perception of visual complexity, structural elements (links, images, words and sections) and aesthetic appearance (organisation, clearness, cleanliness, interestingness and beautifulness) of a Web page. We argue that the results should be used as a further understanding for keeping the balance between aesthetic appearance of a Web page and its visual complexity. Web pages will then be designed that can still be aesthetically attractive but also usable and not overloaded with information for the users.

Toward a definition of visual complexity as an implicit measure of cognitive load

Abstract: The visual complexity of Web pages is much talked about; “complex Web pages are difficult to use,” but often regarded as a subjective decision by the user. This subjective decision is of limited use if we wish to understand the importance of visual complexity, what it means, and how it can be used. We theorize that by understanding a user's visual perception of Web page complexity, we can understand the cognitive effort required for interaction with that page. This is important because by using an easily identifiable measure, such as visual complexity, as an implicit marker of cognitive load, we can design Web pages which are easier to interact with. We have devised an initial empirical experiment, using card sorting and triadic elicitation, to test our theories and assumptions, and have built an initial baseline sequence of 20 Web pages along with a library of qualitative and anecdotal feedback. Using this library, we define visual complexity, ergo perceived interaction complexity, and by taking these pages as “prototypes” and ranking them into a sequence of complexity, we are able to group them into: simple, neutral, and complex. This means we can now work toward a definition of visual complexity as an implicit measure of cognitive load.

Accessibility: a Web engineering approach

Abstract: Currently, the vast majority of web sites do not support accessibility for visually impaired users. Usually, these users have to rely on screen readers: applications that sequentially read the content of a web page in audio. Unfortunately, screen readers are not able to detect the meaning of the different page objects, and thus the implicit semantic knowledge conveyed in the presentation of the page is lost. One approach described in literature to tackle this problem, is the Dante approach, which allows semantic annotation of web pages to provide screen readers with extra (semantic) knowledge to better facilitate the audio presentation of a web page. Until now, such annotations were done manually, and failed for dynamic pages. In this paper, we combine the Dante approach with a web design method, WSDM, to fully automate the generation of the semantic annotation for visually impaired users. To do so, the semantic knowledge gathered during the design process is exploited, and the annotations are generated as a by-product of the design process, requiring no extra effort from the designer.

Exploring the relationship between web accessibility and user experience

Abstract: Understanding the interplay between the user experience (UX) and Web accessibility is key to design Web sites that, beyond access, could provide a better UX for people with disabilities. In this paper we examine the relationship between UX attributes and Web accessibility. We measured accessibility in two ways: the perceived accessibility as reported by participants and accessibility in terms of conformance to guidelines. Findings uncover that perceived Web accessibility is significantly correlated with 27 of the 35 UX attributes analysed, suggesting these two qualities are closely related. The relationship between UX and conformance to WCAG 2.0 is more elusive: we only found significant correlations between the hedonic attributes original, innovative and exciting. HighlightsWe analysed the relationship between perceived accessibility and user experience.Participants' UX and their accessibility perception are significantly related.We examined the relationship between Web accessibility conformance and UX.Original, innovative and exciting attributes are correlated to accessibility.We discuss the practical importance of the identified correlations.

The travails of visually impaired web travellers

Abstract: This paper proposes the inclusion of travel and mobility in the usability metrics of web design. Hypertext design and usability has traditionally concentrated upon navigation and/or orientation. The notion of travel extends navigation and orientation to include environment, mobility and the purpose of the travel task. The presence of travel aids are important for all users, but particularly so for those with a visual impairment. This paper presents the ground work for including travel into web design and usability metrics by presenting a framework for identifying travel objects and registering them as either cues to aid travel or obstacles that hinder travel for visually impaired users. The aim is to maximise cues and minimise obstacles to give high mobility; measured by the mobility index. This framework is based upon a model of real world travel by both sighted and visually impaired people, where travel objects are used for orientation, navigation, route planning and survey knowledge. Knowledge of the differences in travel between visually impaired and sighted people will enable the model to be used in assisting the design of better user agents and web content for visually impaired and other users.

Planck 2018 results: XI. Polarized dust foregrounds

Abstract: The study of polarized dust emission has become entwined with the analysis of the cosmic microwave background (CMB) polarization. We use new Planck maps to characterize Galactic dust emission as a foreground to the CMB polarization. We present Planck EE, BB, and TE power spectra of dust polarization at 353 GHz for six nested sky regions covering from 24 to 71 % of the sky. We present power-law fits to the angular power spectra, yielding evidence for statistically significant variations of the exponents over sky regions and a difference between the values for the EE and BB spectra. The TE correlation and E/B power asymmetry extend to low multipoles that were not included in earlier Planck polarization papers. We also report evidence for a positive TB dust signal. Combining data from Planck and WMAP, we determine the amplitudes and spectral energy distributions (SEDs) of polarized foregrounds, including the correlation between dust and synchrotron polarized emission, for the six sky regions as a function of multipole. This quantifies the challenge of the component separation procedure required for detecting the reionization and recombination peaks of primordial CMB B modes. The SED of polarized dust emission is fit well by a single-temperature modified blackbody emission law from 353 GHz to below 70 GHz. For a dust temperature of 19.6 K, the mean spectral index for dust polarization is $\beta_{\rm d}^{P} = 1.53\pm0.02 $. By fitting multi-frequency cross-spectra, we examine the correlation of the dust polarization maps across frequency. We find no evidence for decorrelation. If the Planck limit for the largest sky region applies to the smaller sky regions observed by sub-orbital experiments, then decorrelation might not be a problem for CMB experiments aiming at a primordial B-mode detection limit on the tensor-to-scalar ratio $r\simeq0.01$ at the recombination peak.

Model Driven Engineering

Abstract: The Object Management Group's (OMG) Model Driven Architecture (MDA) strategy envisages a world where models play a more direct role in software production, being amenable to manipulation and transformation by machine. Model Driven Engineering (MDE) is wider in scope than MDA. MDE combines process and analysis with architecture. This article sets out a framework for model driven engineering, which can be used as a point of reference for activity in this area. It proposes an organisation of the modelling 'space' and how to locate models in that space. It discusses different kinds of mappings between models. It explains why process and architecture are tightly connected. It discusses the importance and nature of tools. It identifies the need for defining families of languages and transformations, and for developing techniques for generating/configuring tools from such definitions. It concludes with a call to align metamodelling with formal language engineering techniques.