User Perception of Smooth Pursuit Target Speed

Gaze-aware interfaces should work on all display sizes. This paper researches whether angular velocity or tangential speed should be kept when scaling a gaze-aware interface based on circular smooth pursuits to another display size. We also address the question of which target speed and which trajectory size feels most comfortable for the users. We present the results of a user study where the participants were asked how they perceived the speed and the radius of a circular moving smooth pursuit target. The data show that the users’ judgment of the optimal speed corresponds with an optimal detection rate. The results also enable us to give an optimal value pair for target speed and trajectory radius. Additionally, we give a functional relation on how to adapt the target speed when scaling the geometry to keep optimal detection rate and user experience.