Human-computer interaction (HCI) is an interdisciplinary research area which concerns the study of interaction between humans (operators as users) and computers. A widely used definition interprets this concept as "a discipline concerned with the design, evaluation and implementation of interactive computing systems for human use and with the study of major phenomena surrounding them" (ACM SIGCHI, 1992). The reason for stating 'interdisciplinary' as the nature of HCI is the involvement of different disciplines contributing to HCI. Computer science is not the only discipline contributing to HCI; other disciplines, such as cognitive psychology, human factors, engineering, design, social and organizational psychology are also considered important and relevant. In the past for many years, a comprehensive range of research and studies concerning different aspects of HCI has been conducted or implemented. These studies are diverse, and include, for instance, dialogue techniques, gestural analysis and multimodal interfaces, computer graphics, computational linguistics, spatial cognition, robot navigation and wayfinding, input styles or devices, and monitor screens etc. However, the ultimate goal of the studies is to contribute to improving the interaction between humans and computer systems by endowing technical systems with higher usability and satisfaction. Facilitating the mutual interaction by presenting information on the status of the computer systems, a user interface normally works as a kind of communication platform or bridge between human beings and computers during the interaction. However, humans work as users operating or controlling the system by processing and interpreting the information. How to design interfaces that assist users in task performance in an optimal manner during interactions is a major challenge for all design engineers. When users interact with computer systems, many factors can influence overall performance. These factors cover various issues from the user side, task side, technical system side, and working environment/context side.