Usability issues and design principles for visual programming languages

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Despite two decades of empirical studies focusing on programmers and the problems with programming, usability of textual programming languages is still hard to achieve. Its younger relation, visual programming languages (VPLs) also share the same problem of poor usability. This research explores and investigates the usability issues relating to VPLs in order to suggest a set of design principles that emphasise usability. The approach adopted focuses on issues arising from the interaction and communication between the human (programmers), the computer (user interface), and the program. Being exploratory in nature, this PhD reviews the literature as a starting point for stimulating and developing research questions and hypotheses that experimental studies were conducted to investigate. However, the literature alone cannot provide a fully comprehensive list of possible usability problems in VPLs so that design principles can be confidently recommended. A commercial VPL was, therefore, holistically evaluated and a comprehensive list of usability problems was obtained from the research. Six empirical studies employing both quantitative and qualitative methodology were undertaken as dictated by the nature of the research. Five of these were controlled experiments and one was qualitative-naturalistic. The experiments studied the effect of a programming paradigm and of representation of program flow on novices' performances. The results indicated superiority of control-flow programs in relation to data-flow programs; a control-flow preference among novices; and in addition that directional representation does not affect performance while traversal direction does - due to cognitive demands imposed upon programmers. Results of the qualitative study included a list of 145 usability problems and these were further categorised into ten problem areas. These findings were integrated with other analytical work based upon the review of the literature in a structured fashion to form a checklist and a set of design principles for VPLs that are empirically grounded and evaluated against existing research in the literature. Furthermore, an extended framework for Cognitive Dimensions of Notations is also discussed and proposed as an evaluation method for diagrammatic VPLs on the basis of the qualitative study. The above consists of the major findings and deliverables of this research. Nevertheless, there are several other findings identified on the basis of the substantial amount of data obtained in the series of experiments carried out, which have made a novel contribution to knowledge in the fields of Human-Computer Interaction, Psychology of Programming, and Visual Programming Languages

CoMoVA - A comprehension measurement framework for visualization systems

Despite the burgeoning interest shown in visualizations by many disciplines, there yet remains the unresolved question concerning comprehension. Is the concept that is being communicated through the visual easily grasped and clearly interpreted? Visual comprehension is that characteristic of any visualization system, which deals with how efficiently and effectively users are able to grasp the underlying concepts through suitable interactions provided for exploring the visually represented information. Comprehension has been considered a very complex subject, which is intangible and subjective in nature. Assessment of comprehension can help to determine the true usefulness of visualization systems to the intended users. A principal contribution of this research is the formulation of an empirical evaluation framework for systematically assessing comprehension support provided by a visualization system to its intended users. To assess comprehension i.e. to measure this seemingly immeasurable factor of visualization systems, we propose a set of criteria based on a detailed analysis of information flow from the raw data to the cognition of information in human mind. Our comprehension criteria are adapted from the pioneering work of two eminent researchers - Donald A. Norman and Aaron Marcus, who have investigated the issues of human perception and cognition, and visual effectiveness respectively. The proposed criteria have been refined with the help of opinions from experts. To gauge and verify the efficacy of these criteria in a practical sense, they were then applied to a bioinformatics visualization study tool and an immersive art visualization environment. Given the vast variety of users and their visualization goals, it may be noted that it is difficult for one to decide on the effectiveness of different visualization tools/techniques in a context independent fashion. We therefore propose an innovative way of evaluating a visualization technique by encapsulating it in a visualization pattern where it is seen as a solution to the visualization problem in a specific context. These visualization patterns guide the tool users/evaluators to compare, understand and select appropriate visualization tools/techniques. Lastly, we propose a novel framework named as CoMoVA (Comprehension Model for Visualization Assessment) that incorporates 'context of use', visualization patterns, visual design principles and important cognitive principles into a coherent whole that can be used to effectively tell us in a more quantifiable manner the benefits of visual representations and interactions provided by a system to the intended audience. Our approach of evaluation of visualization systems is similar to other questionnaire-based approaches such as SUMI (Software Usability Measurement Inventory), where all the questions deal with the measurement of a common trait. We apply this framework to two static software visualization tools in the software visualization domain to demonstrate the practical benefits of using such a framework

Closing The English Language Proficiency Gap In Post-Secondary Education In Canada

The proposed research employed a mixed-method approach to investigate why the linguistic standards of the Canadian Language Benchmark (CLB) (levels 5–8) are deemed satisfactory for English as a second language (ESL) learners at the college level. An examination of the Canadian English Language Proficiency Index Program (CELPIP) identified why an ESL learner with a CLB level of 5–8 requires English support services in post-secondary education to achieve academic success in Canada. The CLB levels of six female participants were analyzed using a questionnaire in reading, writing, listening, and speaking to explore their English levels in articulating the language, pronouncing words, and understanding the meanings in alignment with course materials, assignments, and in-class tasks. Additionally, a focus group discovered a correlation between a participant’s current CLB level and the English support services. The questionnaire and focus group permitted the researcher to discern recurring patterns in their experiences using the English language at the college level

An investigation into the impact of controlled English rules on the comprehensibility, usefulness and acceptability of machine-translated technical documentation for French and German users

Previous studies suggest that the application of Controlled Language (CL) rules can significantly improve the readability, consistency, and machine-translatability of source text. One of the justifications for the application of CL rules is that they can have a similar impact on several target languages by reducing the post-editing effort required to bring Machine Translation (Ml’) output to acceptable quality. In certain situations, however, post-editing services may not always be a viable solution. Web-based information is often expected to be made available in real-time to ensure that its access is not restricted to certain users based on their locale. Uncertainties remain with regard to the actual usefulness of MT output for such users, as no empirical study has examined the impact of CL rules on the usefulness, comprehensibility, and acceptability of MT technical documents from a Web user's perspective. In this study, a two-phase approach is used to determine whether Controlled English rules can have a significant impact on these three variables. First, individual CL rules are evaluated within an experimental environment, which is loosely based on a test suite.Two documents are then published and subject to a randomised evaluation within the framework of an online experiment using a customer satisfaction questionnaire. The findings indicate that a limited number of CL rules have a similar impact on the comprehensibility of French and German output at the segment level. The results of the online experiment show that the application of certain CL rules has the potential to significantly improve the comprehensibility of German MT technical documentation. Our findings also show that the introduction of CL rules did not lead to any significant improvement of the comprehensibility, usefulness, and acceptability of French MT technical documentation

Proceedings of the Second Program Visualization Workshop, 2002

The Program Visualization Workshops aim to bring together researchers who design and construct program visualizations and, above all, educators who use and evaluate visualizations in their teaching. The first workshop took place in July 2000 at Porvoo, Finland. The second workshop was held in cooperation with ACM SIGCSE and took place at HornstrupCentret, Denmark in June 2002, immediately following the ITiCSE 2002 Conference in Aarhus, Denmark

Toward an improved understanding of software change

Structural changes, including moving, renaming, merging and splitting are important design change decisions made by programmers. However, during the process of software evolution, this information often gets lost. Recovering instances of structural changes in the past, as well as understanding them, are essential for us to achieve a better understanding of how and why software changes. In this thesis, we propose an approach that helps to recover and understand the lost information of structural changes