The influence of body orientation relative to gravity on egocentric distance estimates in virtual reality

Virtual reality systems are a popular tool in behavioral sciences. The participants' behavior is, however, a response to cognitively processed stimuli. Consequently, researchers must ensure that virtually perceived stimuli resemble those present in the real world to ensure the ecological validity of collected findings. Our article provides a literature review relating to distance perception in virtual reality. Furthermore, we present a new study that compares verbal distance estimates within real and virtual environments. The virtual space-a replica of a real outdoor area-was displayed using a state-of-the-art head-mounted display. Investigated distances ranged from 8 to 13 m. Overall, the results show no significant difference between egocentric distance estimates in real and virtual environments. However, a more in-depth analysis suggests that the order in which participants were exposed to the two environments may affect the outcome. Furthermore, the study suggests that a rising experience of immersion leads to an alignment of the estimated virtual distances with the real ones. The results also show that the discrepancy between estimates of real and virtual distances increases with the incongruity between virtual and actual eye heights, demonstrating the importance of an accurately set virtual eye height.

The perception of reachability (i.e., whether an object is within reach) relies on body representations and action simulation. Similarly, egocentric distance estimation (i.e., the perception of the distance an object is from the self) is thought to be partly derived from embodied action simulation. Although motor simulation is important for both, it is unclear whether the cognitive processes underlying these behaviors rely on the same motor processes. To investigate this, we measured the impact of a motor interference dual-task paradigm on reachability judgment and egocentric distance estimation, while allocentric length estimation (i.e., how distant two stimuli are from each other independent from the self) was used as a control task. Participants were required to make concurrent actions with either hand actions of foam ball grip squeezing or arm actions of weight lifting, or no concurrent actions. Results showed that concurrent squeeze actions significantly slowed response speed in the reachability judgment and egocentric distance estimation tasks, but that there was no impact of the concurrent actions on allocentric length estimation. Together, these results suggest that reachability and distance perception, both egocentric perspective tasks, and in contrast to the allocentric perspective task, involve action simulation cognitive processes. The results are discussed in terms of the implication of action simulation when evaluating the position of a target relative to the observer’s body, supporting an embodied view of spatial cognition.

Depth perception as well as egocentric distance estimation can be trained in virtual spaces, although incorrect estimates can occur in these environments. To understand this phenomenon, a virtual environment with 11 changeable factors was created. Egocentric distance estimation skills of 239 participants were assessed with it in the range [25 cm, 160 cm]. One hundred fifty-seven people used a desktop display and seventy-two the Gear VR. According to the results, these investigated factors can have various effects combined with the two display devices on distance estimation and its time. Overall, desktop display users are more likely to accurately estimate or overestimate distances, and significant overestimations occur at 130 and 160 cm. With the Gear VR, distances in the range [40 cm, 130 cm] are significantly underestimated, while at 25 cm, they are significantly overestimated. Estimation times are significantly decreased with the Gear VR. When developing future virtual environments that require depth perception skills, developers should take these results into account.

It is well known that eye height is an important visual cue in the perception of apparent sizes and affordances in virtual environments. However, the influence of visual eye height on egocentric distances in virtual environments has received less attention. To explore this influence, we conducted an experiment where we manipulated the virtual eye height of the user in a head-mounted display virtual environment. As a measurement we asked the participants to verbally judge egocentric distances and to give verbal estimates of the dimensions of the virtual room. In addition, we provided the participants a self-animated avatar to investigate if this virtual self-representation has an impact on the accuracy of verbal distance judgments, as recently evidenced for distance judgments accessed with an action-based measure. When controlled for ownership, the avatar had a significant influence on the verbal estimates of egocentric distances as found in previous research. Interestingly, we found that the manipulation of eye height has a significant influence on the verbal estimates of both egocentric distances and the dimensions of the room. We discuss the implications which these research results have on those interested in space perception in both immersive virtual environments and the real world.

Verbal estimates of egocentric distance are usually too short at distances greater than several meters, yet blindfolded walking to previously viewed targets can be surprisingly accurate. We present evidence from three experiments for the existence of two visual pathways with differentencodings of perceived egocentric distance. We found that (1) blind-walking estimates of egocentric distance are consistently more accurate than verbal reports; (2) an indoor versus outdoor environment selectively influences verbal reports; and (3) wearing prism lenses, which displace the visual field vertically, selectively influences the blind-walking estimates. We interpret these results in terms of the two visual systems hypothesis.

The goal was to explore the effect of a moderate-intensity exercise on egocentric distance estimates (the distance between the participant and an object in space) in physically trained and untrained participants (N = 54), divided into three groups of 18 national-level soccer players, 18 sedentary people, and 18 controls. Participants engaged in a distance estimation task at rest, and also while pedalling on an ergocycle for 10 min. at 60% of the maximal aerobic intensity. Estimates were recorded during pre-exercise, stability Phase 1 (between the 1st and the 2nd min. of exercise), Phase 2 (5th to 6th min.), Phase 3, (9th to 10th min.), and immediately after the exercise. Estimates of egocentric distance were more accurate in trained than untrained participants. Perception improved during and after the exercise in comparison with pre-exercise. In addition, the group x exercise interaction indi- cated estimation improved during and after exercise, with more accuracy in the trained than untrained participants. Fitness and moderate aerobic exercise improve the egocentric distance estimation in humans.

The perception of distance to real and virtual objects using two methods of distance estimation (verbal estimation and manual replication) along a 110 foot hallway was tested. Results suggest that verbal estimates of distance may not accurately reflect perceived distances. Replication procedure significantly improves the estimation of the previously viewed object distance. Furthermore, the effects of distance judgment method were greater than were the effects of environment type. The magnitude of the distance judgment error was considerably larger for the estimation condition in the real environment than it was for the replication condition in the augmented environment. These results lend further support to the notion that verbal estimates of distance do not accurately represent perceived distance. Unless the task being performed specifically requires a numerical estimate of distance, it is recommended that methods similar to our distance replication method be used to accurately determine perceived distance.

The aim of this study was to investigate the effect of a total sleep deprivation (TSD) on the egocentric distance estimation following a fatiguing task (i.e. sprint repetitions). Ten soccer players (age: 22.8 ± 1.3 years; weight: 72. 8 ± 10 .5 kg; height: 1.8 ± 0.03 m) were volunteered to participate in the study. Subjects were invited to estimate different distances in two different sessions (i) following a reference night and (ii) following a night of TSD. The distance estimation consists to perceive three different distances (15, 25, and 35 m) before and after a repeated sprint exercise on a cycloergometer. The results demonstrated a significant effect of TSD on the perception of egocentric distance (F (1.9) = 11.22, p < 0.01). Indeed, the results showed an underestimation (compression of the real distance) of all distances at rest and following the repeated sprint exercise. Additionally, the underestimation was more acute after the fatiguing task. TSD affects the estimation of egocentric distance by soccer players at rest and following fatiguing task.

Egocentric distance estimation has been shown to depend on wearing safety gear, which promotes compensatory behavior, and on target type, which regulates fight-or-flight responses. We hypothesized that the two factors interact, possibly in asymmetric fashion, and set out to uncover the limits of this interaction in a perceptual task where individuals wearing helmets or baseball caps estimated egocentric distance to non-threatening and threatening animals depicted on cards (i.e., safe and unsafe targets). We found that, compared to participants wearing caps, participants wearing helmets overshoot distance estimations and were able to distinguish not only between targets situated at two depth levels as participants wearing caps could, but also between safe targets situated at wide and narrow visual angles. Our findings help define the interaction between safety devices and target type, thereby contributing to the debate between advocates of prevention models and those who maintain that these are offset by compensatory strategies.

In three experiments, we scrutinized the dissociation between perception and action, as reflected by the contributions of egocentric and allocentric information. In Experiment 1, participants stood at the base of a large-scale one-tailed version of a Müller-Lyer illusion (with a hoop) and either threw a beanbag to the endpoint of the shaft or verbally estimated the egocentric distance to that location. The results confirmed an effect of the illusion on verbal estimates, but not on throwing, providing evidence for a dissociation between perception and action. In Experiment 2, participants observed a two-tailed version of the Müller-Lyer illusion from a distance of 1.5m and performed the same tasks as in Experiment 1, yet neither the typical illusion effects nor a dissociation became apparent. Experiment 3 was a replication of Experiment 1, with the difference that participants stood at a distance of 1.5m from the base of the one-tailed illusion. The results indicated an illusion effect on both the verbal estimate task and the throwing task; hence, there was no dissociation between perception and action. The presence (Exp. 1) and absence (Exp. 3) of a dissociation between perception and action may indicate that dissociations are a function of the relative availability of egocentric and allocentric information. When distance estimates are purely egocentric, dissociations between perception and action occur. However, when egocentric distance estimates have a (complementary) exocentric component, the use of allocentric information is promoted, and dissociations between perception and action are reduced or absent.

It has been reported by numerous studies on distance perception in VR that a compression of visual space occurs in virtual environments presented using stereoscopic techniques. Other studies have shown that modified environmental auditory cues can affect egocentric spatial perception and that increased order of modality improved the experience of immersive media. Work was conducted to measure the effect of spatialized acoustic cues on egocentric distance estimation in head mounted display VR. Results suggest that the although early reflection content was not found to have significant effect on estimation of distance, presence of reverberation increases the perception of distance for objects further than 5m from the user and can compensate for the spatial compression observed in the use of stereoscopic VR.

The perception and estimation of egocentric distance in real and augmented reality environments

The Perception and Estimation of Egocentric Distance in Real and Augmented Reality Environments

The Perception and Estimation of Egocentric Distance in Real and Augmented Reality Environments

The results of multiple studies conducted in the real world have demonstrated that human observers are usually very accurate in judging egocentric distance (the distance from the observer to a target) up to about 25 meters if the target is located on a continuous ground surface. Sinai et al. [1998] found that the presence of a texture discontinuity on the ground surface leads to distance underestimation. Two experiments were conducted to investigate the effect of a discontinuous ground surface on distance perception in virtual environments (VEs). The first experiment was the replication of Experiment 1 from Wu et al. [2007]. The second experiment involved the manipulation of the position of the texture boundary.