With over 1.3 million applications on the Android marketplace, there is increasing competition between mobile applications for customer sales. As usability is a significant factor in an application’s success, many mobile developers refer to the Android design guidelines when designing the user interface (UI). These principles help to provide consistency of navigation and aesthetics, with the rest of the Android platform. However, misinterpretation of the abstract guidelines may mean that patterns and elements selected to organise content of an application do not improve the usability. Therefore, usability tests would be beneficial to ensure that an application meets objectives efficiently and improve on user experience. Usability testing is an important and crucial step in the mobile development process Many freelance developers, however, have limited resources for usability testing, even though the advantages of usability feedback during initial development stages are clear and can save time and money in the long-run. In this thesis, we investigate which method of usability testing is most useful for resource constrained mobile developers. To test the efficacy of Android guidelines, three alternate designs of a unique Android tablet application, Glycano, are developed. High-fidelity paper prototypes were presented to end-users for usability testing and to usability experts for heuristic evaluations. Both usability and heuristic tests demonstrated that following the Android guidelines aids in user familiarity and learnability. Regardless of the different UI designs of the three mockups, Android guidelines provided an initial level of usability by providing familiarity to proficient users and an intuitiveness of certain patterns to new users. However, efficiency in building Glycano schematics was an issue that arose consistently. Testing with end-users and experts, revealed several navigational problems. Usability experts uncovered more general UI problems than the end-user group, who focused more on the content of the application. More refinements and suggestions of additional features to enhance usability and user experience were provided by the experts. Use of usability experts would therefore be most advantageous in initial design stages of an application. Feedback from usability testing is, however, also beneficial and is more valuable than not performing any test at all.

For any technology to become widely-used and accepted, it must support end-user authoring and customisation. This means making the technology accessible by enabling understanding of its design issues and reducing its technical barriers. Our interest is in enabling end-users to author dynamic virtual environments (VEs), specifically their interactions: player interactions with objects and the environment; and object interactions with each other and the environment. This thesis describes a method to create tools and design aids which enable end-users to design and implement interactions in a VE and assist them in building the requisite domain knowledge, while reducing the costs of learning a new set of skills. Our design method is based in constructivism, which is a theory that examines the acquisition and use of knowledge. It provides principles for managing complexity in knowledge acquisition: multiplicity of representations and perspectives; simplicity of basic components; encouragement of exploration; support for deep reflection; and providing users with control of their process as much as possible. We derived two main design aids from these principles: multiple, interactive and synchronised domain-specific representations of the design; and multiple forms of non-invasive and user-adaptable scaffolding. The method began with extensive research into representations and scaffolding, followed by investigation of the design strategies of experts, the needs of novices and how best to support them with software, and the requirements of the VR domain. We also conducted a classroom observation of the practices of non-programmers in VR design, to discover their specific problems with effectively conceptualising and communicating interactions in VR. Based on our findings in this research and our constructivist guidelines, we developed VRBridge, an interaction authoring tool. This contained a simple event-action interface for creating interactions using trigger-condition-action triads or Triggersets. We conducted two experimental evaluations during the design of VRBridge, to test the effectiveness of our design aids and the basic tool. The first tested the effectiveness of the Triggersets and additional representations: a Floorplan, a Sequence Diagram and Timelines. We used observation, interviews and task success to evaluate how effectively end-users could analyse and debug interactions created with VRBridge. We found that the Triggersets were effective and usable by novices to analyse an interaction design, and that the representations significantly improved end-user work and experience. The second experiment was large-scale (124 participants) and conducted over two weeks. Participants worked on authoring tasks which embodied typical interactions and complexities in the domain. We used a task exploration metric, questionnaires and computer logging to evaluate aspects of task performance: how effectively end-users could create interactions with VRBridge; how effectively they worked in the domain of VR authoring; how much enjoyment or satisfaction they experienced during the process; and how well they learned over time. This experiment tested the entire system and the effects of the scaffolding and representations. We found that all users were able to complete authoring tasks using VRBridge after very little experience with the system and domain; all users improved and felt more satisfaction over time; users with representations or scaffolding as a design aid completed the task more expertly, explored more effectively, felt more satisfaction and learned better than those without design aids; users with representations explored more effectively and felt more satisfaction than those with scaffolding; and users with both design aids learned better but did not improve in any other way over users with a single design aid. We also gained evidence about how the scaffolding, representations and basic tool were used during the evaluation. The contributions of this thesis are: an effective and efficient theory-based design method; a case study in the use of constructivism to structure a design process and deliver effective tools; a proof-of-concept prototype with which novices can create interactions in VR without traditional programming; evidence about the problems that novices face when designing interactions and dealing with unfamiliar programming concepts; empirical evidence about the relative effectiveness of additional representations and scaffolding as support for designing interactions; guidelines for supporting end-user authoring in general; and guidelines for the design of effective interaction authoring systems in general.