Eye movement synthesis with 1/f pink noise

Eye movements are an essential part of non-verbal behavior. Non-player characters (NPCs), as they occur in many games, communicate with the player through dialogues and non-verbal behavior and can have a strong influence on the player experience or even on gameplay. In this paper we propose a procedural model to synthesize the subtleties of eye motions. More specifically, our model adds microsaccadic jitter and pupil unrest both modeled by 1/f or pink noise to the standard main sequence. In a perceptual two-alternative forced-choice (2AFC) experiment we explore the perceived naturalness of different parameters of pink noise by comparing synthesized motions to rendered motion of recorded eye movements at extreme close shot and close shot distances. Our results show that, on average, data-driven motion is perceived as most natural, followed by parameterized pink noise, with motion lacking microsaccadic jitter being consistently selected as the least natural in appearance.