Assessing design features of virtual keyboards for text entry

Objective: The present research examined design of a virtual keyboard for text entry with a rotary controller, emphasizing users who differ in age and system experience. Background: Existing research has minimally addressed usage frequency, age, and the effects of display shape and letter arrangement on movement and visual search components of text entry tasks. The present research was conducted to close these gaps. Method: Two experiments were completed to examine younger (18-28 years) and older (60-75 years) adults' movement and visual search capabilities using four keyboard shapes and three keyboard arrangements. In a third experiment examining combined effects on shape design, 32 younger (18-28 years) and 32 older (60-75 years) adults entered words on the two best shapes from the first experiments. Results: For the movement task, movement time was lowest for shapes with higher shape-controller compatibility. For the visual search task, search time and accuracy were best on the alphabetic arrangement. In the combined task, shape did not significantly influence performance at different levels of practice. Transfers, however, suggested that the shape with salient visual features elicited a text entry strategy for older adults that may promote more consistent performance under occasional usage. Conclusion: The studies together demonstrate that keyboard shape is important for efficient performance. Shape-controller compatibility facilitated performance in both age groups. Salient features facilitate performance, especially for older adults. In nearly all cases alphabetic arrangement yielded the best performance. Application: Recommendations are provided for virtual keyboard design for different usage frequencies, contexts, and users.