Completion Time Predictions of Mobile Touch-Screen Interactions in Dual-Task Situations

As the use of touch input in mobile and kiosk devices is becoming more ubiquitous, the validity of human performance models such as Fitts´ Law must be investigated to determine whether they still hold in situations where users are performing other tasks while interacting with the device. This paper describes an experiment that explores the effect of split attention on the completion time and accuracy of an interactive touch selection task. It was found that the task completion time, the error rate, and the spatial variability of target selections increased significantly when attention was not solely focused on the interactive task. Consequently, the paper suggests specific guidelines for the design of ubiquitous computing devices used in split attention environments.