Papers by Stephen Palmisano
Virtual Reality
During head-mounted display (HMD)-based virtual reality (VR), head movements and motion-to-photon... more During head-mounted display (HMD)-based virtual reality (VR), head movements and motion-to-photon-based display lag generate differences in our virtual and physical head pose (referred to as DVP). We propose that large-amplitude, time-varying patterns of DVP serve as the primary trigger for cybersickness under such conditions. We test this hypothesis by measuring the sickness and estimating the DVP experienced under different levels of experimentally imposed display lag (ranging from 0 to 222 ms on top of the VR system's ~ 4 ms baseline lag). On each trial, seated participants made continuous, oscillatory head rotations in yaw, pitch or roll while viewing a large virtual room with an Oculus Rift CV1 HMD (head movements were timed to a computer-generated metronome set at either 1.0 or 0.5 Hz). After the experiment, their head-tracking data were used to objectively estimate the DVP during each trial. The mean, peak, and standard deviation of these DVP data were then compared to the participant's cybersickness ratings for that trial. Irrespective of the axis, or the speed, of the participant's head movements, the severity of their cybersickness was found to increase with each of these three DVP summary measures. In line with our DVP hypothesis, cybersickness consistently increased with the amplitude and the variability of our participants' DVP. DVP similarly predicted their conscious experiences during HMD VR-such as the strength of their feelings of spatial presence and their perception of the virtual scene's stability.
Virtual Reality
While head-mounted display (HMD) based gaming is often limited by cybersickness, research suggest... more While head-mounted display (HMD) based gaming is often limited by cybersickness, research suggests that repeated exposure to virtual reality (VR) can reduce the severity of these symptoms. This study was therefore aimed at: (1) examining the exposure conditions required to reduce cybersickness during HMD VR; and (2) learning whether such reductions generalise from one HMD VR game to another. Our participants played two commercially-available HMD VR video games over two consecutive days. Their first exposure to HMD VR on both days was always to a 15-min virtual rollercoaster ride. On Day 1, half of our participants also played a virtual climbing game for 15-min, while the rest of them finished testing early. Participants in the latter group were only exposed to the climbing game late on Day 2. We found that sickness was significantly reduced for our participants on their second exposure to the virtual rollercoaster. However, sickness to the rollercoaster on Day 2 was unaffected by wh...
Paper presented at the Australasian Experimental Psychology Conference 2015, 8-11 April 2015, Syd... more Paper presented at the Australasian Experimental Psychology Conference 2015, 8-11 April 2015, Sydney, Australia. Keywords without, visual, motion, reduces, subsequent, vection, walking Disciplines Education | Social and Behavioral Sciences Publication Details Palmisano, S., Seno, T., Riecke, B. & Nakamura, S. (2015). Walking without visual motion reduces subsequent vection. Australasian Experimental Psychology Conference 2015 This conference paper is available at Research Online: http://ro.uow.edu.au/sspapers/1585 apply two standard accumulation models – the diffusion (Ratcliff & McKoon, 2008) and the LBA (Brown & Heathcote, 2008) – to the detection of heterogeneous multi-‐attribute targets in a simulated unmanned-‐aerial-‐vehicle operator task. Despite responses taking two seconds or more and complications added by realistic features such as a complex target classification rule, interruptions from a simultaneous navigation task and time pressured choices about several simultaneo...
Correlations between vection measures and sway area ratios (log transformed)
PLOS ONE, 2014
<p>(a–c) Expanding vection; (d–f) Contracting vection. (a, d) Verbal ratings. (b, e) Thrott... more <p>(a–c) Expanding vection; (d–f) Contracting vection. (a, d) Verbal ratings. (b, e) Throttle maximum values. (c,f) Latency.</p
Proceedings of the 27th ACM Symposium on Virtual Reality Software and Technology, 2021
The relationship between vection (illusory self-motion) and cybersickness is complex. This pilot ... more The relationship between vection (illusory self-motion) and cybersickness is complex. This pilot study examined whether only unexpected vection provokes sickness during head-mounted display (HMD) based virtual reality (VR). 20 participants ran through the tutorial of Mission: ISS (an HMD VR app) until they experienced notable sickness (maximum exposure was 15 minutes). We found that: 1) cybersickness was positively related to vection strength; and 2) cybersickness appeared to be more likely to occur during unexpected vection. Given the implications of these findings, future studies should attempt to replicate them and confirm the unexpected vection hypothesis with larger sample sizes and rigorous experimental designs. CCS CONCEPTS • Human-centered computing → Visualization; Visualization theory, concepts and paradigms.
PLOS ONE, 2018
Typically it takes up to 10 seconds or more to induce a visual illusion of self-motion ("vection"... more Typically it takes up to 10 seconds or more to induce a visual illusion of self-motion ("vection"). However, for this vection to be most useful in virtual reality and vehicle simulation, it needs to be induced quickly, if not immediately. This study examined whether vection onset latency could be reduced towards zero using visual display manipulations alone. In the main experiments, visual self-motion simulations were presented to observers via either a large external display or a head-mounted display (HMD). Priming observers with visually simulated viewpoint oscillation for just ten seconds before the main self-motion display was found to markedly reduce vection onset latencies (and also increase ratings of vection strength) in both experiments. As in earlier studies, incorporating this simulated viewpoint oscillation into the self-motion displays themselves was also found to improve vection. Average onset latencies were reduced from 8-9s in the no oscillating control condition to as little as 4.6 s (for external displays) or 1.7 s (for HMDs) in the combined oscillation condition (when both the visual prime and the main self-motion display were oscillating). As these display manipulations did not appear to increase the likelihood or severity of motion sickness in the current study, they could possibly be used to enhance computer generated simulation experiences and training in the future, at no additional cost.
Displays, 2018
Cybersickness is common during virtual reality experiences with head-mounted displays (HMDs). Pre... more Cybersickness is common during virtual reality experiences with head-mounted displays (HMDs). Previously it has been shown that individual differences in postural activity can predict which people are more likely to experience visually-induced motion sickness. This study examined whether such predictions also generalise to the cybersickness experienced during active HMD-based virtual reality. Multisensory stimulation was generated by having participants continuously turn their heads from left to right while viewing the self-motion simulations. Real-time head tracking was then used to create ecological ('compensated') and non-ecological ('inversely compensated') head-and-display motion conditions. Ten (out of 20) participants reported feeling sick after being exposed to these self-motion simulations. Cybersickness did not differ significantly between the two compensation conditions. However, individual differences in spontaneous postural instability when standing quietly were found to predict the likelihood of subsequently experiencing cybersickness. These findings support recent proposals that postural measures can help diagnose who will benefit the most/least from HMD-based virtual reality.
Displays, 2017
Cybersickness is often experienced when viewing virtual environments through head-mounted display... more Cybersickness is often experienced when viewing virtual environments through head-mounted displays (HMDs). This study examined whether vection (i.e., illusory self-motion) and mismatches between perceived and physical head motions contribute to such adverse experiences. Observers made oscillatory yaw head rotations while viewing stereoscopic optic flow through an Oculus Rift HMD. Vection and cybersickness were measured under 3 conditions of visual compensation for physical head movements: "compensated", "uncompensated", and "inversely compensated". When a nearer aperture was simulated by the HMD, vection was found to be strongest in the "compensated" condition and weakest in the "inversely compensated" condition. However, vection was similar for all 3 conditions during full-field exposures. Cybersickness was most severe for the "inversely compensated" condition, but was not different for the other two conditions. We conclude that mismatches between perceived and physical head-movements can contribute strongly to cybersickness. The relationship between vection and cybersickness is weaker and appears complex.
Multisensory Research, 2013
Visually induced illusory self-motion (vection) was facilitated by active breaststroke arm and bo... more Visually induced illusory self-motion (vection) was facilitated by active breaststroke arm and body movements. Optic flow was generated by having the standing observer make these arm movements, which were detected by Kinect and incorporated into the display. When generated, this optic flow was either expanding (i.e. congruent with the observer’s head motion) or contracting (i.e. incongruent with his/her head motion). Optic flow generated during these active movement conditions was also later played back to the observer during passive viewing conditions. On each of these trials, we recorded vection strength (latency, duration and magnitude). We found that: (i) both congruent and incongruent breaststroke movements increased vection (i.e. compared to passive viewing conditions); and (ii) congruent breaststroke movements increased vection more than incongruent ones. We name the enhancement provided by this type of active movement ‘virtual swimming’. This demonstration shows that even un...
PloS one, 2014
Visually-induced illusions of self-motion (vection) can be compelling for some people, but they a... more Visually-induced illusions of self-motion (vection) can be compelling for some people, but they are subject to large individual variations in strength. Do these variations depend, at least in part, on the extent to which people rely on vision to maintain their postural stability? We investigated by comparing physical posture measures to subjective vection ratings. Using a Bertec balance plate in a brightly-lit room, we measured 13 participants' excursions of the centre of foot pressure (CoP) over a 60-second period with eyes open and with eyes closed during quiet stance. Subsequently, we collected vection strength ratings for large optic flow displays while seated, using both verbal ratings and online throttle measures. We also collected measures of postural sway (changes in anterior-posterior CoP) in response to the same visual motion stimuli while standing on the plate. The magnitude of standing sway in response to expanding optic flow (in comparison to blank fixation periods)...
USING VPYTHON FOR PSYCHOPHYSICS | Guterman
Vection Change Exacerbates Simulator Sickness in Virtual Environments
Presence: Teleoperators and Virtual Environments, 2008
The optic flow patterns generated by virtual reality (VR) systems typically produce visually indu... more The optic flow patterns generated by virtual reality (VR) systems typically produce visually induced experiences of self-motion (vection). While this vection can enhance presence in VR, it is often accompanied by a variant of motion sickness called simulator sickness (SS). However, not all vection experiences are the same. In terms of perceived heading and/or speed, visually simulated self-motion can be either steady or changing. It was hypothesized that changing vection would lead to more SS. Participants viewed an optic flow pattern that either steadily expanded or alternately expanded and contracted. In one experiment, SS was measured pretreatment and after 5 min of viewing using the Simulator Sickness Questionnaire. In a second experiment employing the same stimuli, vection onset and magnitude were measured using a computer-interfaced slide indicator. The steadily expanding flow pattern, compared to the expanding and contracting pattern, led to: 1) significantly less SS, 2) lowe...
The Role of Perceived Speed in Vection: Does Perceived Speed Modulate the Jitter and Oscillation Advantages?
PLoS ONE, 2014
Perception, 2012
A new vection illusion is reported. Vection was induced even though there was no consciously perc... more A new vection illusion is reported. Vection was induced even though there was no consciously perceived global display motion corresponding to the self-motion. The resulting experience can be summarised as: “I feel that I am moving but I do not know why”.
Perception, 2002
Previous research found that adding stereoscopic information to radially expanding optic flow dec... more Previous research found that adding stereoscopic information to radially expanding optic flow decreased vection onsets and increased vection durations (Palmisano, 1996 Perception & Psychophysics58 1168–1176). In the current experiments, stereoscopic cues were also found to increase perceptions of vection speed and self-displacement during vection in depth—but only when these cues were consistent with monocularly available information about self-motion. Stereoscopic information did not appear to be improving vection by increasing the perceived maximum extent of displays or by making displays appear more three-dimensional. Rather, it appeared that consistent patterns of stereoscopic optic flow provided extra, purely binocular information about vection speed, which resulted in faster/more compelling illusions of self-motion in depth.
Vection Induced by Illusory Motion in a Stationary Image
Perception, 2013
Ilusory self-motion (vection) can be induced by large areas of visual motion stimulation. Here we... more Ilusory self-motion (vection) can be induced by large areas of visual motion stimulation. Here we demonstrate for the first time that illusory expansion can induce vection in the absence of any physical display motion.
Perception, 2012
Hunger was found to facilitate visually induced illusory upward and downward self-motions (vertic... more Hunger was found to facilitate visually induced illusory upward and downward self-motions (vertical vection), but not illusory self-motion in depth (vection in depth). We propose that the origin of this hunger effect lies in the possibility that vertical self-motions (both real and illusory) are more likely to induce changes in visceral state.
Refractive error and monocular viewing strengthen the hollow-face illusion
Perception, 2012
We measured the strength of the hollow-face illusion—the ‘flipping distance’ at which perception ... more We measured the strength of the hollow-face illusion—the ‘flipping distance’ at which perception changes between convex and concave—as a function of a lens-induced 3 dioptre refractive error and monocular/binocular viewing. Refractive error and closing one eye both strengthened the illusion to approximately the same extent. The illusion was weakest viewed binocularly without refractive error and strongest viewed monocularly with it. This suggests binocular cues disambiguate the illusion at greater distances than monocular cues, but that both are disrupted by refractive error. We argue that refractive error leaves the ambiguous low-spatial-frequency shading information critical to the illusion largely unaffected while disrupting other, potentially disambiguating, depth/distance cues.
Perception, 2011
We directly compared recognition for faces following 0° – 75° viewpoint rotation about the yaw, p... more We directly compared recognition for faces following 0° – 75° viewpoint rotation about the yaw, pitch, and roll axes. The aim was to determine the extent to which configural and featural information supported face recognition following rotations about each of these axes. Experiment 1 showed that performance on a sequential-matching task was viewpoint-dependent for all three types of rotation. The best face-recognition accuracy and shortest reaction time was found for roll rotations, then for yaw rotations, and finally the worst accuracy and slowest reaction time was found for pitch rotations. Directional differences in recognition were found for pitch rotations, but not for roll or yaw. Experiment 2 provided evidence that, in all three cases, viewpoint-dependent declines in recognition were primarily driven by the loss of configural information. However, it also appeared that significant featural information was lost following yaw and pitch (but not roll) rotations. Together, these ...
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Papers by Stephen Palmisano