ChromaGazer: Unobtrusive Visual Modulation using Imperceptible Color Vibration for Visual Guidance

Visual guidance (VG) is critical for directing user attention in virtual and augmented reality applications. However, conventional methods using explicit visual annotations can obstruct visibility and increase cognitive load. To address this, we propose an unobtrusive VG technique based on color vibration, a phenomenon in which rapidly alternating colors at frequencies above 25 Hz are perceived as a single intermediate color. We hypothesize that an intermediate perceptual state exists between complete color fusion and perceptual flicker, where colors appear subtly different from a uniform color without conscious perception of flicker. To investigate this, we conducted two experiments. First, we determined the thresholds between complete fusion, the intermediate state, and perceptual flicker by varying the amplitude of color vibration pairs in a user study. Second, we applied these threshold parameters to modulate regions in natural images and evaluated their effectiveness in guiding users' gaze using eye-tracking data. Our results show that color vibration can subtly guide gaze while minimizing cognitive load, providing a novel approach for unobtrusive VG in VR and AR applications.