I Am The Passenger: How Visual Motion Cues Can Influence Sickness For In-Car VR

This paper explores the use of VR Head Mounted Displays (HMDs) in-car and in-motion for the first time. Immersive HMDs are becoming everyday consumer items and, as they offer new possibilities for entertainment and productivity, people will want to use them during travel in, for example, autonomous cars. However, their use is confounded by motion sickness caused in-part by the restricted visual perception of motion conflicting with physically perceived vehicle motion (accelerations/rotations detected by the vestibular system). Whilst VR HMDs restrict visual perception of motion, they could also render it virtually, potentially alleviating sensory conflict. To study this problem, we conducted the first on-road and in motion study to systematically investigate the effects of various visual presentations of the real-world motion of a car on the sickness and immersion of VR HMD wearing passengers. We established new baselines for VR in-car motion sickness, and found that there is no one best presentation with respect to balancing sickness and immersion. Instead, user preferences suggest different solutions are required for differently susceptible users to provide usable VR in-car. This work provides formative insights for VR designers and an entry point for further research into enabling use of VR HMDs, and the rich experiences they offer, when travelling

Personalising Vibrotactile Displays through Perceptual Sensitivity Adjustment

Haptic displays are commonly limited to transmitting a discrete set of tactile motives. In this paper, we explore the transmission of real-valued information through vibrotactile displays. We simulate spatial continuity with three perceptual models commonly used to create phantom sensations: the linear, logarithmic and power model. We show that these generic models lead to limited decoding precision, and propose a method for model personalization adjusting to idiosyncratic and spatial variations in perceptual sensitivity. We evaluate this approach using two haptic display layouts: circular, worn around the wrist and the upper arm, and straight, worn along the forearm. Results of a user study measuring continuous value decoding precision show that users were able to decode continuous values with relatively high accuracy (4.4% mean error), circular layouts performed particularly well, and personalisation through sensitivity adjustment increased decoding precision

Distance Perception in Virtual Environment through Head-mounted Displays

Head-mounted displays (HMDs) are popular and affordable wearable display devices which facilitate immersive and interactive viewing experience. Numerous studies have reported that people typically underestimate distances in HMDs. This dissertation describes a series of research experiments that examined the influence of FOV and peripheral vision on distance perception in HMDs and attempts to provide useful information to HMD manufacturers and software developers to improve perceptual performance of HMD-based virtual environments. This document is divided into two main parts. The first part describes two experiments that examined distance judgments in Oculus Rift HMDs. Unlike numerous studies found significant distance compression, our Experiment I & II using the Oculus DK1 and DK2 found that people could judge distances near-accurately between 2 to 5 meters. In the second part of this document, we describe four experiments that examined the influence of FOV and human periphery on distance perception in HMDs and explored some potential approaches of augmenting peripheral vision in HMDs. In Experiment III, we reconfirmed the peripheral stimulation effect found by Jones et al. using bright peripheral frames. We also discovered that there is no linear correlation between the stimulation and peripheral brightness. In Experiment IV, we examined the interaction between the peripheral brightness and distance judgments using peripheral frames with different relative luminances. We found that there exists a brightness threshold; i.e., a minimum brightness level that\u27s required to trigger the peripheral stimulation effect which improves distance judgments in HMD-based virtual environments. In Experiment V, we examined the influence of applying a pixelation effect in the periphery which simulates the visual experience of having a peripheral low-resolution display around viewports. The result showed that adding the pixelated peripheral frame significantly improves distance judgments in HMDs. Lastly, our Experiment VI examined the influence of image size and shape in HMDs on distance perception. We found that making the frame thinner to increase the FOV of imagery improves the distance judgments. The result supports the hypothesis that FOV influences distance judgments in HMDs. It also suggests that the image shape may have no influence on distance judgments in HMDs

Change blindness: eradication of gestalt strategies

Arrays of eight, texture-defined rectangles were used as stimuli in a one-shot change blindness (CB) task where there was a 50% chance that one rectangle would change orientation between two successive presentations separated by an interval. CB was eliminated by cueing the target rectangle in the first stimulus, reduced by cueing in the interval and unaffected by cueing in the second presentation. This supports the idea that a representation was formed that persisted through the interval before being 'overwritten' by the second presentation (Landman et al, 2003 Vision Research 43149–164]. Another possibility is that participants used some kind of grouping or Gestalt strategy. To test this we changed the spatial position of the rectangles in the second presentation by shifting them along imaginary spokes (by ±1 degree) emanating from the central fixation point. There was no significant difference seen in performance between this and the standard task [F(1,4)=2.565, p=0.185]. This may suggest two things: (i) Gestalt grouping is not used as a strategy in these tasks, and (ii) it gives further weight to the argument that objects may be stored and retrieved from a pre-attentional store during this task

Visuo-vestibular interaction in the reconstruction of travelled trajectories

We recently published a study of the reconstruction of passively travelled trajectories from optic flow. Perception was prone to illusions in a number of conditions, and not always veridical in the others. Part of the illusionary reconstructed trajectories could be explained by assuming that subjects base their reconstruction on the ego-motion percept built during the stimulus' initial moments . In the current paper, we test this hypothesis using a novel paradigm: if the final reconstruction is governed by the initial percept, providing additional, extra-retinal information that modifies the initial percept should predictably alter the final reconstruction. The extra-retinal stimulus was tuned to supplement the information that was under-represented or ambiguous in the optic flow: the subjects were physically displaced or rotated at the onset of the visual stimulus. A highly asymmetric velocity profile (high acceleration, very low deceleration) was used. Subjects were required to guide an input device (in the form of a model vehicle; we measured position and orientation) along the perceived trajectory. We show for the first time that a vestibular stimulus of short duration can influence the perception of a much longer lasting visual stimulus. Perception of the ego-motion translation component in the visual stimulus was improved by a linear physical displacement: perception of the ego-motion rotation component by a physical rotation. This led to a more veridical reconstruction in some conditions, but to a less veridical reconstruction in other conditions

Reconstructing passively travelled manoeuvres: Visuo-vestibular interactions.

We recently published a study of the reconstruction of passively travelled trajectories from optic flow. Perception was prone to illusions in a number of conditions, and not always veridical in the other conditions. Part of the illusionary reconstructed trajectories could be explained if we assume that the subjects based their reconstruction on the ego-motion percept obtained during the stimulus' initial moments. In the current paper, we test this hypothesis using a novel paradigm. If indeed the final reconstruction is governed by the initial percept, then additional, extra-retinal information that modifies the initial percept should predictably alter the final reconstruction. We supplied extra-retinal stimuli tuned to supplement the information that was underrepresented or ambiguous in the optic flow: the subjects were physically displaced or rotated at the onset of the visual stimulus. A highly asymmetric velocity profile (high acceleration, very low deceleration) was used. Subjects were required to guide an input device (in the form of a model vehicle; we measured position and orientation) along the perceived trajectory. We show for the first time that a vestibular stimulus of short duration can influence the perception of a much longer lasting visual stimulus. Perception of the ego-motion translation component in the visual stimulus was improved by a linear physical displacement; perception of the ego-motion rotation component by a physical rotation. This led to a more veridical reconstruction in some conditions, but it could also lead to less veridical reconstructions in other conditions