| Summary: | 博士 === 國立成功大學 === 工業設計學系 === 104 === Mobile phone touchscreens have many ergonomic problems related to text entry. Previous studies, which were attempts to use ambiguous keyboards to resolve problems related to small keys, have focused on the disambiguation process without consideration of the user loading on a graphic user interface. This study investigates user loadings, which interfere with performance in the key selection phase when people are using an ambiguous keyboard. Typing efficiency experiment related to the disambiguation phase were also conducted in this study. Hence, three QWERTY-like ambiguous keyboards and a standard QWERTY keyboard were compared via visual search, manual operation and text entry efficiency experiments. The visual search experiment showed that layouts with many letters per key were strongly related to long visual search times, and the Hick-Hyman lay failed to predict users’ performance on ambiguous keyboards. In addition, keyboard layouts with large keys were operated faster and more accurately in the manual operation experiment. In addition, users’ manual performance could be predicting by the Fitts’ law. Consequently, the trade-off between visual and manual loading differed among different letter-key assignments. In addition, the typing efficiency experiment showed the importance of previous typing experience and the compatibility between operating posture and keyboard layouts.
This study is important in that it elucidates the impacts of visual and manual loadings on ambiguous keyboards, as well as the fact that it provides user interface designers with an enhanced understanding of how to design ambiguous keyboards based on user criteria. Meanwhile, future work could build a cognitive model of ambiguous keyboard operation based on the findings of this study, and a new concept of “adaptive user interface” was proposed based on the findings as well.
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