The impact of visual and motor space size on gaze-based target selection

ObjectivePrevious studies have demonstrated that making a target larger is sufficient to compensate for the inaccuracy of gaze-based target selection. However, few studies systemically examined the individual contribution of the target's motor and visual space size in gaze selection. We investigated how the motor and visual space size affect gaze-based target selection.MethodExperiment 1 was used to examine the effect of the invisible expanded motor space in a 2D target selection task under hand-based and gaze-based control modes. Experiment 2 was used to examine the impact of the invisible expanded motor space on gaze-based target selection performance with different visual-space sizes.ResultsAs the motor-space size increased, participants selected targets more efficiently and experienced less frustration and temporal demand; these effects were more pronounced in the gaze-based control mode. The selection was faster in the group with a larger visual-space size. Moreover, there were significant interactions between visual-space size and motor-space size on the throughput of gaze-based selection, which refers to the efficiency of input method that containing the accuracy and speed. These interactions also significantly affected endpoint distance variation and effort demand.ConclusionsThe motor-space size, even invisible, is the determining factor in facilitating the gaze selection performance. Additionally, the size of the visual space has a feedforward effect on selection speed and modulates the effect of motor space. These findings provide insights into the contribution of these two spaces and a new perspective to optimize the gaze-based interface. What is already known about this topic: A common way to enhance gaze positioning accuracy is to enlarge the region where the gaze resides in the motor and visual space. However, this method also brings visual interference problems.The invisible motor-only expansion could facilitate the one-dimensional (1D) gaze-based target selection performance and 2D mouse pointing time.Visual feedforward and feedback contribute to the perception of target size, resulting in improving the efficiency of hand-controlled pointing.What this topic adds: The motor-space size, even invisible, is the determining factor in facilitating the performance of 2D gaze-based target selection, and it affects more in gaze-controlled mode than in hand-controlled mode.The design in the visual space of a target could provide the user with feedforward and feedback information that helps improve the efficiency and user experience of 2D gaze-based target selection.Visual-space size could also modulate the effects of motor-space size on the stability and throughput of 2D gaze-based selection.