Degree Name

Doctor of Philosophy


School of Information Systems Technology


Internationally, the last decade has seen a proliferation in the use of mobile devices in both business and social contexts. Complementary to this increased use of mobile devices is a developing research agenda focusing on the issues of device mobility and ubiquity for interpersonal communication and work-based activities. Understanding the nature of the relationship between user, environment and device in relation to mobile device usability and user experience is a major challenge for researchers and designers. Indeed, central to this challenge is the need to develop and employ appropriate mobile device Usability Evaluation Methods (UEMs) that recognise context-of-use variables and how they impact user experience. To gain insight into the user experience context-of-use dynamic this study employed a combination of qualitative and quantitative data gathering methods. Task-based user testing across six different scenarios that emulate every-day mobile interaction tasks was conducted. The scenarios were attempted by 41 participants on three different devices and the common errors made during the ‘everyday’ mobile interaction tasks were recorded. Different theories of behaviour and learning including Activity Theory (AT) and Cognitive Load Theory (CLT) were applied to explain the relationship between how the devices were used in different contexts and the tasks performed by the participants. A theoretical explanation of human error was achieved by adapting and extending Zapf et al.’s ‘taxonomy of errors’. A key finding to emerge from this study is that laboratory-based usability testing produces high-quality usability data from actual users with mobile devices. The effectiveness of such testing however has a high degree of variance depending on what data is collected and how the data are analysed. As a result, practical guidance is required to support effective laboratory testing whilst simulating context-of-use scenarios. This study developed an approach consisting of six steps to outline the approach necessary for the contextual evaluation of any mobile device. The six steps are: Requirements; Environment; Set-up; Testing; Evaluation and Reporting (RESTER). This approach can be applied in any context-of-use environment. A relationship exists between human activity, errors and cognitive load when using any device. As such, an investigation of the issues associated with user experience when interacting with mobile devices, primarily interaction with the device interface, iii is beneficial to our understanding of mobile device usability and design domains. The findings presented in this study may be used to address assumptions and implications related to the structure and complexity of interface designs and how they may best meet the needs of user. This study theoretically contributes to the development of a usability evaluation methods for mobile devices, as well as the development of our understanding of the overall user experience focusing on the error analysis.