Objective: This study aims to investigate the mouse cursor trajectory during tasks involving pointing at a target moving in a two-dimensional space, and to compare it with the trajectory observed during stationary target pointing.

Background: The traditional Fitts' law, which describes the time and accuracy of pointing tasks, fails to explain tasks involving moving targets. To understand the characteristics of pointing at a moving target, research on the movement trajectory of the mouse cursor is required. Although studies on cursor trajectories have been conducted previously, they have been limited to investigating trajectories during stationary target pointing tasks.

Method: The time interval from the initiation of cursor movement to the target click was divided into five stages. In each stage, we measured and analyzed whether the cursor position was located above or below the straight line connecting the starting point and the destination. Changes in the cursor position were measured while systematically varying the target speed, target size, and the distance between the target and the starting point.

Results: Stationary target pointing placed the cursor below the line in Stages 1~2 and above in Stages 3~5, whereas moving targets showed the opposite trend, which became more pronounced at higher speeds. Furthermore, while there were 32 possible mouse cursor trajectories for target pointing, participants utilized only 6 trajectories 75.8% of the time, demonstrating a preference for simple paths over complex ones. For moving targets, the preferred paths were Below-Below-Below- Below-Below (22.9%), Above-Below-Below-Below-Below (13.6%), and Above-Above- Below-Below-Below (8.1%). For stationary targets, the preferred paths were Above- Above-Above-Above-Above (14.8%), Below-Below-Above-Above-Above (9.0%) and Below-Above-Above-Above-Above (7.4%).

Conclusion: The mouse cursor movement trajectories for pointing at stationary targets differed significantly from those for pointing at moving targets. This discrepancy in cursor trajectories is expected to influence pointing times. Therefore, when developing a modified Fitts' law for moving targets, models that incorporate these variations in cursor trajectories should be proposed.

Application: The findings of this study offer valuable insights into understanding and leveraging the characteristics of moving target pointing tasks.