Abstract
In recent years, with the development of touch screen technology and multi-touch products, portable devices with high interaction are popular in the market. With the popularity of 3G mobile network and the growing demands on mobile entertainment, the users may experience some differences in browsing or text input touch screen and button interface design. This study aims to investigate text input of smartphones for performance evaluation and usability study. Previous studies focused more on Pinyin input assessment, so this study will take the Zhuyin input and handwriting input as evaluation factors. This study will also discuss whether there are significant differences on text input performance in mobilephone operating system (iOS, Android), input tool (finger, stylus), screen direction (vertical, horizontal) and different version of Android operating system. For dependment measures, the objective measures include the subject's completion time and error rate. The subjective measures include mental workload scale (NASA-TLX) and system usability scale (SUS). The results showed that there were significant differences in completion time and error rate between different age group. The worst performance was found in the older group. The findings implicated that the age factor should be considered in the interface design. In the input method, the young and the middle-aged people had better performance in the keyboard input and the older people showed better performance in handwriting input. In input tools, the use of the stylus for text input had better performance than that of using fingers. In screen direction, the vertical operation was better than the horizontal operation. For the operating system, the use of Android operating system had better performance in Chinese input, while the use of iOS operating system had better performance in English input.