We provide the first perceptual quantification of user's sensitivity to radial optic flow artifacts and demonstrate a promising approach for masking this optic flow artifact via blink suppression. Near-eye HMOs allow users to feel immersed in virtual environments by providing visual cues, like motion parallax and stereoscopy, that mimic how we view the physical world. However, these systems exhibit a variety of perceptual artifacts that can limit their usability and the user's sense of presence in VR. One well-known artifact is the vergence-accommodation conflict (VAC). Varifocal displays can mitigate VAC, but bring with them other artifacts such as a change in virtual image size (radial optic flow) when the focal plane changes. We conducted a set of psychophysical studies to measure users' ability to perceive this radial flow artifact before, during, and after self-initiated blinks. Our results showed that visual sensitivity was reduced by a factor of 10 at the start and for ~70 ms after a blink was detected. Pre- and post-blink sensitivity was, on average, ~O.15% image size change during normal viewing and increased to ~1.5- 2.0% during blinks. Our results imply that a rapid (under 70 ms) radial optic flow distortion can go unnoticed during a blink. Furthermore, our results provide empirical data that can be used to inform engineering requirements for both hardware design and software-based graphical correction algorithms for future varifocal near-eye displays. Our project website is available at https://gamma.umd.edu/ROF/.

When using a see-through augmented reality head-mounted display system (AR HMD), a user’s perception of virtual content may be degraded by a variety of perceptual artifacts resulting from the architecture of rendering and display pipelines. In particular, virtual content that is rendered to appear stationary in the real world (worldlocked) can be susceptible to spatial and temporal 3D position errors. A subset of these errors, termed jitter, result from mismatches between the spatial localization, rendering, and display pipelines, and can manifest as perceived motion of intended-to-be stationary content. Here, we employ psychophysical methods to quantify the perceptibility of jitter artifacts in an AR HMD. For some viewing conditions, participants perceived jitter that was smaller than the pixel pitch of the testbed (i.e., subpixel jitter). In general, we found that jitter perceptibility increased as viewing distance increased and decreased as background luminance increased. We did not find that the contrast ratio of virtual content, age, or experience with AR/VR modulatedjitter perceptibility. Taken together, this study quantifies the degree of jitter that a user can perceive in an AR HMD and demonstrates that it is critical to consider the capabilities and limits of the human visual system when designing the next generation of spatial computing platforms.

Eye movements have provided an excellent substrate with which to explore the neural control of motor systems. The simplicity of the neural circuitry and physical plants, in comparison to visually directed limb movements, allow for much easier analysis and extrapolation. The adaptive capabilities of eye movements are robust and reflect the significant neural plasticity within these systems. Although crucial for optimal motor function, these adaptive properties and the neural mechanisms responsible are only beginning to be understood. While limb and saccadic adaptations have been intensively studied, the adaptive response is measured indirectly as a change in the original response. Vergence, however, appears to provide the opportunity to measure the adaptive response in isolation. The following are preliminary results of a study investigating the adaptive properties of vergence eye movements using a main sequence analysis. The effects of stimulus directionality and amplitude are investigated and compared to the reflexive vergence innervation patterns known to exist to similar stimuli.