First Person Perspective of Seated Participants Over a Walking Virtual Body Leads to Illusory Agency Over the Walking

Agency, the attribution of authorship to an action of our body, requires the intention to carry out the action, and subsequently a match between its predicted and actual sensory consequences. However, illusory agency can be generated through priming of the action together with perception of bodily action, even when there has been no actual corresponding action. Here we show that participants can have the illusion of agency over the walking of a virtual body even though in reality they are seated and only allowed head movements. The experiment (n = 28) had two factors: Perspective (1PP or 3PP) and Head Sway (Sway or NoSway). Participants in 1PP saw a life-sized virtual body spatially coincident with their own from a first person perspective, or the virtual body from third person perspective (3PP). In the Sway condition the viewpoint included a walking animation, but not in NoSway. The results show strong illusions of body ownership, agency and walking, in the 1PP compared to the 3PP condition, and an enhanced level of arousal while the walking was up a virtual hill. Sway reduced the level of agency. We conclude with a discussion of the results in the light of current theories of agency

The Effects of Visuomotor Calibration to the Perceived Space and Body, through Embodiment in Immersive Virtual Reality

We easily adapt to changes in the environment that involve cross-sensory discrepancies (e.g., between vision and proprioception). Adaptation can lead to changes in motor commands so that the experienced sensory consequences are appropriate for the new environment (e.g., we program a movement differently while wearing prisms that shift our visual space). In addition to these motor changes, perceptual judgments of space can also be altered (e.g., how far can I reach with my arm?). However, in previous studies that assessed perceptual judgments of space after visuomotor adaptation, the manipulation was always a planar spatial shift, whereas changes in body perception could not directly be assessed. In this study, we investigated the effects of velocity-dependent (spatiotemporal) and spatial scaling distortions of arm movements on space and body perception, taking advantage of immersive virtual reality. Exploiting the perceptual illusion of embodiment in an entire virtual body, we endowed subjects with new spatiotemporal or spatial 3D mappings between motor commands and their sensory consequences. The results imply that spatiotemporal manipulation of 2 and 4 times faster can significantly change participants’ proprioceptive judgments of a virtual object’s size without affecting the perceived body ownership, although it did affect the agency of the movements. Equivalent spatial manipulations of 11 and 22 degrees of angular offset also had a significant effect on the perceived virtual object’s size; however, the mismatched information did not affect either the sense of body ownership or agency. We conclude that adaptation to spatial and spatiotemporal distortion can similarly change our perception of space, although spatiotemporal distortions can more easily be detected

Embodying compassion: A virtual reality paradigm for overcoming excessive self-criticism

Virtual reality has been successfully used to study and treat psychological disorders such as phobias and posttraumatic stress disorder but has rarely been applied to clinically-relevant emotions other than fear and anxiety. Self-criticism is a ubiquitous feature of psychopathology and can be treated by increasing levels of self-compassion. We exploited the known effects of identification with a virtual body to arrange for healthy female volunteers high in self-criticism to experience self-compassion from an embodied first-person perspective within immersive virtual reality. Whereas observation and practice of compassionate responses reduced self-criticism, the additional experience of embodiment also increased self-compassion and feelings of being safe. The results suggest potential new uses for immersive virtual reality in a range of clinical conditions.N/

Characterizing first and third person viewpoints and their alternation for embodied interaction in virtual reality

Empirical research on the bodily self has shown that the body representation is malleable, and prone to manipulation when conflicting sensory stimuli are presented. Using Virtual Reality (VR) we assessed the effects of manipulating multisensory feedback (full body control and visuo-tactile congruence) and visual perspective (first and third person perspective) on the sense of embodying a virtual body that was exposed to a virtual threat. We also investigated how subjects behave when the possibility of alternating between first and third person perspective at will was presented. Our results support that illusory ownership of a virtual body can be achieved in both first and third person perspectives under congruent visuo-motor-tactile condition. However, subjective body ownership and reaction to threat were generally stronger for first person perspective and alternating condition than for third person perspective. This suggests that the possibility of alternating perspective is compatible with a strong sense of embodiment, which is meaningful for the design of new embodied VR experiences

As light as your scent: effects of smell and sound on body image perception

How people mentally represent their body appearance (i.e., body image perception - BIP) does not always match their actual body. BIP distortions can lead to a detriment in physical and emotional health. Recent works in HCI have shown that technology can be used to change people’s BIP through visual, tactile, proprioceptive, and auditory stimulation. This paper investigates, for the first time, the effect of olfactory stimuli, by looking at a possible enhancement of a known auditory effect on BIP.We present two studies building on emerging knowledge in the field of crossmodal correspondences. First, we explored the correspondences between scents and body shapes. Then, we investigated the impact of combined scents and sounds on one’s own BIP. Our results show that scent stimuli can be used to make participants feel lighter or heavier (i.e., using lemon or vanilla) and to enhance the effect of sound on perceived body lightness. We discuss how these findings can inform future research and design directions to overcome body misperception and create novel augmented and embodied experiences

Up, down, near, far: an online vestibular contribution to distance judgement

Whether a visual stimulus seems near or far away depends partly on its vertical elevation. Contrasting theories suggest either that perception of distance could vary with elevation, because of memory of previous upwards efforts in climbing to overcome gravity, or because of fear of falling associated with the downwards direction. The vestibular system provides a fundamental signal for the downward direction of gravity, but the relation between this signal and depth perception remains unexplored. Here we report an experiment on vestibular contributions to depth perception, using Virtual Reality. We asked participants to judge the absolute distance of an object presented on a plane at different elevations during brief artificial vestibular inputs. Relative to distance estimates collected with the object at the level of horizon, participants tended to overestimate distances when the object was presented above the level of horizon and the head was tilted upward and underestimate them when the object was presented below the level of horizon. Interestingly, adding artificial vestibular inputs strengthened these distance biases, showing that online multisensory signals, and not only stored information, contribute to such distance illusions. Our results support the gravity theory of depth perception, and show that vestibular signals make an on-line contribution to the perception of effort, and thus of distance

Do I trust you, abstract creature?: a study on personality perception of abstract virtual faces

Studies in the field of social psychology have shown evidence that the dimensions of human facial features can directly impact the perception of personality of that human. Traits such as aggressiveness, trustworthiness and dominance have been directly correlated with facial features. If the same correlations were true for virtual faces, this could be a valuable design guideline to direct the creation of characters with intended personalities. In particular, this is relevant for extremely abstract characters that have minimal facial features (often seen in video games and movies), and rely heavily on these features for portraying personality. We conducted an exploratory study in order to retrieve insights about the way certain facial features affect the perceived personality, as well as affinity of very abstract virtual faces. We specifically tested the effect of different head shapes, eye shapes and eye sizes. Interestingly, our findings show that the same rules for real human faces do not apply to the perception of abstract faces, and in some cases are the complete reverse. These results provide us with a better understanding of the perception of abstract virtual faces, and a starting point for the creation of guidelines for how to portray personality using minimal facial cues

Turbulent Motions Cannot Shake VR

The International Air Transport Association forecasts that there will be at least a 30 increase in passenger demand for flights over the next five years. In these circumstances the aircraft industry is looking for new ways to keep passengers occupied, entertained and healthy, and one of the methods under consideration is immersive virtual reality. It is therefore becoming important to understand how motion sickness and presence in virtual reality are influenced by physical motion. We were specifically interested in the use of head-mounted displays (HMD) while experiencing in-flight motions such as turbulence. 50 people were tested in different virtual environments varying in their context (virtual airplane versus magic carpet ride over tropical islands) and the way the physical motion was incorporated into the virtual world (matching visual and auditory stimuli versus no incorporation). Participants were subjected to three brief periods of turbulent motions realized with a motion simulator. Physiological signals (postural stability, heart rate and skin conductance) as well as subjective experiences (sickness and presence questionnaires) were measured. None of our participants experienced severe motion sickness during the experiment and although there were only small differences between conditions we found indications that it is beneficial for both wellbeing and presence to choose a virtual environment in which turbulent motions could be plausible and perceived as part of the scenario. Therefore we can conclude that brief exposure to turbulent motions does not get participants sick