The Study of Model for Two-Handed Pointing Tasks in Pen + Touch Interfaces

In pen + touch interfaces, two-handed pointing tasks are quite basic. We focus on two-handed pointing tasks on a stationary touchable tablet under asynchronous conditions, in which another target will not appear until one target is touched and dwelled. Fitts' law cannot accurately model such pointing tasks based on the results of our pilot study. This paper seeks to establish an ergonomics model for bimanual pointing tasks under asynchronous interaction. We designed and implemented three experiments with bimanual pointing tasks varying the target widths and distances. A series of bimanual pointing tasks with ten different IDs (Index of Difficulty) were carried out by 18 participants. The movement time (MT) and errors were collected and analyzed. Through experiments, we found that the index of difficulty of pointing tasks has a significant impact on MT (F9,170 = 6.276, p <; 0.001). Our proposed model achieves a fit of R² = 0.973, while the Fitts' law model only achieves a fit of R² = 0.623. The experimental results show that our model has a strong effectiveness and applicability for bimanual pointing tasks in pen + touch interfaces.