Investigating the usability of touch-based user interfaces

With the emergence of pen-and-touch operated personal digital assistants (PDAs), tablet computers, and wall-size displays (e.g., Liveboard and Smartboard), touch and pen input have gained popularity. Touch-based user interfaces such as mobile phones, PDAs and tablet PCs (with touch screens) have become more attractive in consumer electronics because they enable quick learning and rapid performance whilst evoking high user satisfaction. Today, countless supermarket checkouts, restaurant tills, automated-teller machines, airport check-in kiosks, museum information-booths and voting kiosks use touchscreens. Nevertheless, initial literature identified that the widespread use of a touch-based user interface has been limited by the high error rates shown in many studies, the lack of precision, the fatigue in arm motion, and the concern for screen smudging. Furthermore, most research into touch-based interaction has tended to not directly investigate efficiency, effectiveness and user satisfaction. There is therefore a need to add to the body of knowledge in this area, especially as devices using touch-based interaction are becoming more pervasive. Hence, the purpose of this research is to evaluate the usability of touch-based user interfaces in terms of efficiency, effectiveness and user satisfaction. In order to answer the question of whether a touch-based user interface is better - more effective, useful, practical and satisfying to the user -, an investigation of comparison to other, alternative interaction methods, by means of mouse, touch and stylus has been conducted. Therefore, the research sets out to concentrate on a series of empirical experiments that will be designed and developed to evaluate the efficiency, effectiveness and user satisfaction of using touchscreen interfaces. Furthermore, in order to collect the human performance data, a series of small software prototypes involving touch-based interaction were developed and designed using Adobe Flash. Initially a pilot experiment is carried out and followed by the abstract experiment and context experiment that were based on the guidance of The International Organization for Standardization known as ISO (ISO 9241-420, 2011). The abstract experiment consist of four tests (Tracing test, Dragging test, One direction test and Multi directional test) which are deliberately developed as abstract tasks with the purpose of analysing the user’s ability on simple tasks without a real world context. The context experiment consist of four tests as well (Tracing test, Dragging test, One direction test and Multi directional test) which are deliberately developed as contextual tasks with the purpose of analysing the user’s ability in a real world context. Overall, the aim of both abstract and context experiments was to discover if there are differences in mouse, stylus and touch on the tracing test and dragging test with different levels of difficulty that could affect users’ performance and satisfaction. The significant contribution to knowledge that may arise from this research might provoke the gaining of evidence to show if touch-based interaction is more effective and preferred by users in real-world-type tasks and scenarios. Currently there is very little evidence to indicate whether touch-based interaction is more effective and preferred by users. It seems that the proliferation of touch-based devices is market-driven rather than usability-driven. Moreover, this is the first study that has been carried out which compare three input devices (stylus, mouse and touch) in tracing, dragging, one direction tapping and multi directional tapping test for both abstract and context tasks and therefore contributes to the up-to-date HCI literature. The main strength of the current study is that it provides findings from well-designed experiment that is based on ISO standard (ISO 9241-420, 2011). It provided a useful guideline that can be further developed and applied to other research in this area.