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Empathy, a cornerstone of social interaction, involves shared representation, eliciting vicarious emotions. However, its influence on shared perceptual representations, particularly in foundational domains such as distance perception, remains unexplored. In this study, we introduce a novel adaptation of the empathy for pain task to investigate empathy's influence on distance perception. We also examine how two personality traits, trait empathy and alexithymia, modulate this relationship. Utilizing eye-tracking technology, we examine how attention allocation to different facial and bodily features affects empathy's impact on distance perception. Our findings indicate that empathy biases individuals to perceive targets as closer, with trait empathy reinforcing this effect and alexithymia attenuating it. Furthermore, we demonstrate that heightened attention to eyes and face correlates with perceiving targets as closer, while attention to hand shows the opposite trend. These results underscore the broader influence of empathy beyond shared emotions, revealing its capacity to alter perceptual processes. By elucidating the interplay between personality traits and visual inputs in shaping these alterations, our study offers valuable insights for future research exploring the role of shared representation in empathy across various perceptual domains., (© 2024. The Author(s).)

People naturally seek an interpersonal distance that feels comfortable, striking a balance between not being too close or too far from others until reaching a state of equilibrium. Previous studies on interpersonal distance preferences among autistic individuals have yielded inconsistent results. Some show a preference for greater distance, while others indicate a preference for shorter distances, or reveal higher variance in preferences among autistic individuals. In a related vein, previous studies have also investigated the way autistics accurately judge distance, and these studies have received inconsistent results, with some showing superior spatial abilities and others indicating biases in distance estimations. However, the link between distance estimation and preference has never been examined. To address this gap, our study measured interpersonal distance preferences and estimations and tested the correlation between the two factors. The results indicate greater variance among autistic people in both the preference of distance and the ability to estimate distance accurately, suggesting that inconsistencies in previous studies originate from greater individual differences among autistics. Furthermore, only among autistic individuals were interpersonal distance preference and estimation bias associated in a manner that violated equilibrium. Underestimation bias (judging others as closer than they are) was linked to a preference for closer proximity, while overestimation bias (judging others as further away) was associated with a preference for maintaining a greater distance. This connection suggests that biases in the estimation of interpersonal distance contribute to extreme preferences (being too close or too far away). Taken together, the findings suggest that biases in the estimation of interpersonal distance are associated with socially inappropriate distance preferences among autistics., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Givon-Benjio et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

An important aspect of perceptual learning involves understanding how well individuals can perceive distances, sizes, and time-to-contact. Oftentimes, the primary goal in these experiments is to assess participants' errors (i.e., how accurately participants perform these tasks). However, the manner in which researchers have quantified error, or task accuracy, has varied. The use of different measures of task accuracy, to include error scores, ratios, and raw estimates, indicates that the interpretation of findings depends on the measure of task accuracy utilized. In an effort to better understand this issue, we used a Monte Carlo simulation to evaluate five dependent measures of accuracy: raw distance judgments, a ratio of true to estimated distance judgments, relative error, signed error, and absolute error. We simulated data consistent with prior findings in the distance perception literature and evaluated how findings and interpretations vary as a function of the measure of accuracy used. We found there to be differences in both statistical findings (e.g., overall model fit, mean square error, Type I error rate) and the interpretations of those findings. The costs and benefits of utilizing each accuracy measure for quantifying accuracy in distance estimation studies are discussed., (© 2024. The Psychonomic Society, Inc.)

The influence of travel time on perceived traveled distance has often been studied, but the results are inconsistent regarding the relationship between the two magnitudes. We argue that this is due to differences in the lengths of investigated travel distances and hypothesize that the influence of travel time differs for rather short compared to rather long traveled distances. We tested this hypothesis in a virtual environment presented on a desktop as well as through a head-mounted display. Our results show that, for longer distances, more travel time leads to longer perceived distance, while we do not find an influence of travel time on shorter distances. The presentation through an HMD vs. desktop only influenced distance judgments in the short distance condition. These results are in line with the idea that the influence of travel time varies by the length of the traveled distance, and provide insights on the question of how distance perception in path integration studies is affected by travel time, thereby resolving inconsistencies reported in previous studies., (© 2024. The Author(s).)

How does the human visual system assess the separation between pairs of stimuli in a frontal plane? According to the direct (or subtractive) view the system finds the difference between the positions of the stimuli in a localization system. According to the indirect (or additive) view the system finds the number of instances of a distance unit lying between representations of the stimuli. Critically, position is explicitly represented under the direct view, with separation being derived from position. Position is not explicitly represented under the indirect view; separation is consequently inferred by counting an internal unit of distance. Recent results favor the indirect over the direct view of separation assessment. Dissociations between assessments of separation and position, various context effects in the assessment of separation, and suggestions that position information is not cleanly accessed argue against the direct view. At the same time, various context effects in separation assessment argue for the indirect view. Recent findings regarding the brain bases of vision are consistent with the indirect view. In short, recent results suggest that assessing the separation between two frontal stimuli involves integrating distance units between representations of the stimuli., Competing Interests: The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Dopkins.)

In the post-epidemic era, the restart of China's inbound tourism is imminent. However, there are gaps in our current understanding of how distance perception dynamically affects inbound tourism in China. In order to understand the past patterns of inbound tourism in China, we mapped the data of 61 countries of origin from 2004 to 2018 into a dynamic expanding gravity model to understand the effects of cultural distance, institutional distance, geographical distance, and economic distance on inbound tourism in China and revealed the dynamic interaction mechanism of non-economic distance perception on inbound tourism in China. Our research results show that cultural distance has a positive impact on China's inbound tourism, while institutional distance has a negative impact. The significant finding is that the dynamic interaction of the above two kinds of perceived distance can still have a positive impact on China's inbound tourism. Its practical significance is that it can counteract the influence of institutional distance by strengthening the cultural distance. Generally speaking, geographical distance and institutional distance restrict China's inbound tourism flow, while cultural distance, economic distance, and interactive perceptual distance promote China's inbound tourism flow., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Li et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

During the pandemic of coronavirus disease 2019 (COVID-19), many jurisdictions around the world introduced a "social distance" rule under which people are instructed to keep a certain distance from others. Generally, this rule is implemented simply by telling people how many metres or feet of separation should be kept, without giving them precise instructions as to how the specified distance can be measured. Consequently, the rule is effective only to the extent that people are able to gauge this distance through their space perception. To examine the effectiveness of the rule from this point of view, this study empirically investigated how much distance people would leave from another person when they relied on their perception of this distance. Participants ( N  = 153) were asked to stand exactly 1.5 m away from a researcher, and resultant interpersonal distances showed that while their mean was close to the correct 1.5 m distance, they exhibited large individual differences. These results suggest that a number of people would not stay sufficiently away from others even when they intend to do proper social distancing. Given this outcome, it is suggested that official health advice include measures that compensate for this tendency., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Shadows in physical space are copious, yet the impact of specific shadow placement and their abundance is yet to be determined in virtual environments. This experiment aimed to identify whether a target's shadow was used as a distance indicator in the presence of binocular distance cues. Six lighting conditions were created and presented in virtual reality for participants to perform a perceptual matching task. The task was repeated in a cluttered and sparse environment, where the number of cast shadows (and their placement) varied. Performance in this task was measured by the directional bias of distance estimates and variability of responses. No significant difference was found between the sparse and cluttered environments, however due to the large amount of variance, one explanation is that some participants utilised the clutter objects as anchors to aid them, while others found them distracting. Under-setting of distances was found in all conditions and environments, as predicted. Having an ambient light source produced the most variable and inaccurate estimates of distance, whereas lighting positioned above the target reduced the mis-estimation of distances perceived., (© 2024. The Author(s).)

To achieve a stable perception of object size in spite of variations in viewing distance, our visual system needs to combine retinal image information and distance cues. Previous research has shown that, not only retinal cues, but also extraretinal sensory signals can provide reliable information about depth and that different neural networks (perception versus action) can exhibit preferences in the use of these different sources of information during size-distance computations. Semantic knowledge of distance, a purely cognitive signal, can also provide distance information. Do the perception and action systems show differences in their ability to use this information in calculating object size and distance? To address this question, we presented 'glow-in-the-dark' objects of different physical sizes at different real distances in a completely dark room. Participants viewed the objects monocularly through a 1-mm pinhole. They either estimated the size and distance of the objects or attempted to grasp them. Semantic knowledge was manipulated by providing an auditory cue about the actual distance of the object: "20 cm", "30 cm", and "40 cm". We found that semantic knowledge of distance contributed to some extent to size constancy operations during perceptual estimation and grasping, but size constancy was never fully restored. Importantly, the contribution of knowledge about distance to size constancy was equivalent between perception and action. Overall, our study reveals similarities and differences between the perception and action systems in the use of semantic distance knowledge and suggests that this cognitive signal is useful but not a reliable depth cue for size constancy under restricted viewing conditions., Competing Interests: Declaration of competing interest The authors declare no competing financial interests., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

This study aimed to evaluate the effect of anti-pandemic measures, including wearing a face mask and receiving vaccinations, on interpersonal distance (IPD) during the normalization stage of the COVID-19 pandemic. Virtual reality (VR) technology was used to simulate the experimental environment and a confederate in different conditions. Thirty-one participants were asked to approach the virtual confederate, who could exhibit three vaccination states and two mask-wearing conditions, actively and passively in both indoor and outdoor environments. ANOVA results showed that the participants kept a smaller IPD from the confederate wearing a face mask (IPD = 125.6 cm) than from the one without a face mask (IPD = 154.2 cm). The effects of vaccination states were significant, with the largest distance for an unvaccinated confederate (IPD = 182.3 cm) and the smallest distance for the confederate who had received a booster vaccine (IPD = 111.5 cm). Significant effects of environment were also found, with the participants maintaining a larger IPD in an outdoor environment (IPD = 143.4 cm) than in an indoor room (IPD = 136.4 cm). Additionally, the IPD collected when the participants were passively approached (IPD = 149.6 cm) was significantly larger than that obtained when they actively approached the confederate (IPD = 130.3 cm). Moreover, when the participants faced a confederate who had received a booster vaccine and wore a mask, the IPD was not significantly different from that collected before the COVID-19 pandemic in both the active and passive patterns. These findings help us to better understand the nature of IPD and human behaviors during the normalization stage of the pandemic and provide scientific suggestions for policymakers to develop pandemic-prevention measures., (© 2023 The Authors. PsyCh Journal published by Institute of Psychology, Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd.)

The space immediately around the body, referred to as the peripersonal space (PPS), plays a crucial role in interactions with external objects and in avoiding unsafe situations. This study aimed to investigate whether the size of the PPS changes depending on direction, with a particular focus on the disparity between the front and rear spaces. A vibrotactile stimulus was presented to measure PPS while a task-irrelevant auditory stimulus (probe) approached the participant. In addition, to evaluate the effect of the probe, a baseline condition was used in which only tactile stimuli were presented. The results showed that the auditory facilitation effect of the tactile stimulus was greater in the rear condition than in the front condition. Conversely, the performance on tasks related to auditory distance perception and sound speed estimation did not differ between the two directions, indicating that the difference in the auditory facilitation effect between directions cannot be explained by these factors. These findings indicate that the strength of audio-tactile integration is greater in the rear space compared to the front space, suggesting that the representation of the PPS differed between the front and rear spaces., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The perception of the distance to a sound source is relevant in many everyday situations, not only in real spaces, but also in virtual reality (VR) environments. Where real rooms often reach their limits, VR offers far-reaching possibilities to simulate a wide range of acoustic scenarios. However, in virtual room acoustics a plausible reproduction of distance-related cues can be challenging. In the present study, we compared the detection of changes of the distance to a sound source and its neurocognitive correlates in a real and a virtual reverberant environment, using an active auditory oddball paradigm and EEG measures. The main goal was to test whether the experiments in the virtual and real environments produced equivalent behavioral and EEG results. Three loudspeakers were placed at ego-centric distances of 2 m (near), 4 m (center), and 8 m (far) in front of the participants (N = 20), each 66 cm below their ear level. Sequences of 500 ms noise stimuli were presented either from the center position (standards, 80 % of trials) or from the near or far position (targets, 10 % each). The participants had to indicate a target position via a joystick response ("near" or "far"). Sounds were emitted either by real loudspeakers in the real environment or rendered and played back for the corresponding positions via headphones in the virtual environment. In addition, within both environments, loudness of the auditory stimuli was either unaltered (natural loudness) or the loudness cue was manipulated, so that all three loudspeakers were perceived equally loud at the listener's position (matched loudness). The EEG analysis focused on the mismatch negativity (MMN), P3a, and P3b as correlates of deviance detection, attentional orientation, and context-updating/stimulus evaluation, respectively. Overall, behavioral data showed that detection of the target positions was reduced within the virtual environment, and especially when loudness was matched. Except for slight latency shifts in the virtual environment, EEG analysis indicated comparable patterns within both environments and independent of loudness settings. Thus, while the neurocognitive processing of changes in distance appears to be similar in virtual and real spaces, a proper representation of loudness appears to be crucial to achieve a good task performance in virtual acoustic environments., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Since COVID-19 is easily transmitted among people in close physical proximity, the focus of epidemiological policy during the COVID-19 crisis included major restrictions on interpersonal distance. However, the way in which distance restrictions affected spatial perception is unclear. In the current study, we examined interpersonal distance preferences and perceptions at three time points: pre-pandemic, early post-pandemic, and late post-pandemic. The results indicate that following the pandemic outbreak, people perceived others as farther away than they actually were, suggesting that the distance restrictions were associated with an enlargement of perceived interpersonal distance. Interestingly, however, people maintained the same distance from one another as before the outbreak, indicating no change in actual distance behavior due to the risk of infection. These findings suggest that COVID-19 was associated with a change in the way distance is perceived, while in practice, people maintain the same distance as before. In contrast, COVID-related anxiety predicted both a preference for maintaining a greater distance and a bias toward underestimating perceived distance from others. Thus, individuals who were highly fearful of COVID-19 perceived other people to be closer than they actually were and preferred to maintain a larger distance from them. The results suggest that subjective risk can lead to an increased perception of danger and a subsequent change in behavior. Taken together, even when behaviors should logically change, the decision-making process can be based on distorted perceptions. This insight may be used to predict public compliance., (© 2024. The Author(s).)

Many previous studies have investigated visual distance perception, especially for small to moderate distances. Few experiments, however, have evaluated the perception of large distances (e.g., 100 m or more). The studies that have been conducted have found conflicting results (diametrically opposite conclusions). In the current experiment, the functions relating actual and perceived distance were obtained for sixteen adult observers using the method of equal appearing intervals. These functions relating perceived and actual distance were obtained for outdoor viewing in a typical University environment-the experiment was conducted along a sidewalk adjacent to a typical street where campus buildings, trees, street signs, etc., were visible. The overall results indicated perceptual compression of distances in depth so that the stimulus distance intervals appeared significantly shorter than the actual (physical) distance intervals. It is important to note, however, that there were sizeable individual differences-the judgments of half of the observers were relatively accurate, whereas the judgments of the remaining half were inaccurate to varying degrees. The results of the experiment demonstrate that there is no single function that describes how human observers visually perceive large distance intervals in outdoor environments., (© 2024. The Author(s).)

This paper presents a novel approach to enhance the discrimination capacity of multi-scattered point objects in bat bio-sonar. A broadband interferometer mathematical model is developed, incorporating both distance and azimuth information, to simulate the transmitted and received signals of bats. The Fourier transform is employed to simulate the preprocessing step of bat information for feature extraction. Furthermore, the bat bio-sonar model based on convolutional neural network (BS-CNN) is constructed to compensate for the limitations of conventional machine learning and CNN networks, including three strategies: Mix-up data enhancement, joint feature and hybrid atrous convolution module. The proposed BS-CNN model emulates the perceptual nerves of the bat brain for distance-azimuth discrimination and compares with four conventional classifiers to assess its discrimination efficacy. Experimental results demonstrate that the overall discrimination accuracy of the BS-CNN model is 93.4%, surpassing conventional CNN networks and machine learning methods by at least 5.9%. This improvement validates the efficacy of the BS-CNN bionic model in enhancing the discrimination accuracy in bat bio-sonar and offers valuable references for radar and sonar target classification., (© 2024 IOP Publishing Ltd.)

Goal-directed approaches to perception usually consider that distance perception is shaped by the body and its potential for interaction. Although this phenomenon has been extensively investigated in the field of perception, little is known about the effect of motor interactions on memory, and how they shape the global representation of large-scale spaces. To investigate this question, we designed an immersive virtual reality environment in which participants had to learn the positions of several items. Half of the participants had to physically (but virtually) grab the items with their hand and drop them at specified locations (active condition). The other half of the participants were simply shown the items which appeared at the specified position without interacting with them (passive condition). Half of the items used during learning were images of manipulable objects, and the other half were non manipulable objects. Participants were subsequently asked to draw a map of the virtual environment from memory, and to position all the items in it. Results show that active participants recalled the global shape of the spatial layout less precisely, and made more absolute distance errors than passive participants. Moreover, global scaling compression bias was higher for active participants than for passive participants. Interestingly, manipulable items showed a greater compression bias compared to non-manipulable items, yet they had no effect on correlation scores and absolute non-directional distance errors. These results are discussed according to grounded approaches of spatial cognition, emphasizing motor simulation as a possible mechanism for position retrieval from memory., (© 2024. The Author(s).)

In the real world, every object has its canonical distance from observers. For example, airplanes are usually far away from us, whereas eyeglasses are close to us. Do we have an internal representation of the canonical real-world distance of objects in our cognitive system? If we do, does the canonical distance influence the perceived size of an object? Here, we conducted two experiments to address these questions. In Experiment 1, we first asked participants to rate the canonical distance of objects. Participants gave consistent ratings to each object. Then, pairs of object images were presented one by one in a trial, and participants were asked to rate the distance of the second object (i.e., a priming paradigm). We found that the rating of the perceived distance of the target object was modulated by the canonical real-world distance of the prime. In Experiment 2, participants were asked to judge the perceived size of canonically near or far objects that were presented at the converging end (i.e., far location) or the opening end (i.e., near location) of a background image with converging lines. We found that regardless of the presentation location, participants perceived the canonically near object as smaller than the canonically far object even though their retinal and real-world sizes were matched. In all, our results suggest that we have an internal representation of the canonical real-world distance of objects, which affects the perceived distance of subsequent objects and the perceived size of the objects themselves.

Objectives: Child pedestrian injuries represent a significant public health challenge. Understanding the most complex cognitive skills required to cross streets helps us understand, improve, and protect children in traffic, as underdeveloped cognitive skill likely impacts children's pedestrian safety. One complex component of street-crossing is the cognitive-perceptual task of judging time-to-arrival of oncoming traffic. We examined capacity of 7- and 8-year-olds to judge time-to-arrival for vehicles approaching from varying distances and speeds, as well as improvement in those judgments following intensive street-crossing training in a virtual reality (VR) pedestrian simulator., Methods: 500 seven- and eight-year-olds participated in a randomized trial evaluating use of a large kiosk VR versus smartphone-based VR headset to teach street-crossing skills. Prior to randomization into VR training condition and also prior to initiation of any training, children engaged in a video-based vehicle approach estimation task to assess ability to judge traffic time-to-arrival. They then engaged in multiple VR-based pedestrian safety training sessions in their randomly assigned condition until achieving adult functioning. Soon after training and again 6 months later, children repeated the vehicle estimation task., Results: Prior to randomization or training, children were more accurate judging time to arrival for closer versus farther traffic, and rapidly-moving versus slower-moving traffic, but those results were subsumed by a speed x distance interaction. The interaction suggested distance cues were used more prominently than speed cues, and speed had varying effects at different distances. Training group had minimal effect on learning and all children became significantly better at judging vehicle arrival times following training., Conclusions: Children tend to underestimate vehicle arrival times. Distance cues are more impactful on time-to-arrival judgments than speed cues, but children's estimations based both on manipulations of vehicle speed and manipulations of vehicle distance improved post-training. Improvements were retained six months later. This finding is consistent with psychophysics research suggesting vehicle approach judgments rely on optical size and looming, which are impacted both by vehicle speeds and distances. Implementation of VR-based training for child pedestrian safety is recommended, as it may improve children's judgment of vehicle time-to-arrival, but it must be conducted cautiously to avoid iatrogenic effects.

Despite its mathematical simplicity and ubiquity in imaging technology, there has long been doubt about the ability of linear perspective to best represent human visual space, especially at wide-angle fields of view under natural viewing conditions. We investigated whether changes to image geometry had an impact on participants' performance, specifically in terms of non-metric distance estimates. Our multidisciplinary research team developed a new open-source image database to study distance perception in images by systematically manipulating target distance, field of view, and image projection using non-linear natural perspective projections. The database consists of 12 outdoor scenes of a virtual three-dimensional urban environment in which a target ball is presented at increasing distance, visualised using both linear perspective and natural perspective images, rendered, respectively, with three different fields of view: 100°, 120°, and 140° horizontally. In the first experiment ( N  = 52), we tested the effects of linear versus natural perspective on non-metric distance judgements. In the second experiment ( N  = 195), we investigated the influence of contextual and previous familiarity with linear perspective, and individual differences in spatial skills on distance estimations. The results of both experiments showed that distance estimation accuracy improved in natural compared with linear perspective images, particularly at wide-angle fields of view. Moreover, undertaking a training session with only natural perspective images led to more accurate distance judgements overall. We argue that the efficacy of natural perspective may stem from its resemblance to the way objects appear under natural viewing conditions, and that this can provide insights into the phenomenological structure of visual space., Competing Interests: Declaration of conflicting interestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: The authors whose names are listed immediately below declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.Author names: N.R., J.G., and K.P.The authors whose names are listed immediately below report the following details of affiliation in an organisation with a financial interest in the materials discussed in this manuscript. The authors have equity ownership in Fovo Technology Ltd, the sponsor who funded the research reported in Experiment 1 of this paper. The technology developed by Fovo Technology Ltd. was used to generate the stimuli used in the current paper. They may financially benefit from this interest, if Fovo Technology Ltd. is successful in marketing products related to this research. The terms of this arrangement have been reviewed and approved by Cardiff Metropolitan University in accordance with its policy on objectivity in research. The authors were not involved in the data collection nor data analysis of the studies reported in the present manuscript.Author names: R.P. and A.B.

Distances are commonly underperceived in virtual reality (VR), and this finding has been documented repeatedly over more than two decades of research. Yet, there is evidence that perceived distance is more accurate in modern compared to older head-mounted displays (HMDs). This meta-analysis, based on 137 samples from 61 publications, describes egocentric distance perception across 20 HMDs and examines the relationship between perceived distance and technical HMD characteristics. Judged distance was positively associated with HMD field of view (FOV), positively associated with HMD resolution, and negatively associated with HMD weight. The effects of FOV and resolution were more pronounced among heavier HMDs. These findings suggest that future improvements in these technical characteristics may be central to resolving the problem of distance underperception in VR.

construal underlies mental travel. As a result, the human mind associates abstraction and psychological distance, whereby prompting abstract construal begets the inference of psychological distance - in time, social distance, hypotheticality, and physical space. That final distance is the only dimension that can be appraised visually, so would abstract construal impact judgments related to perceived visual distance? Two experiments provide evidence that abstract construal causes targets in the visual field to be judged as physically farther away. Further, the exacerbated sense of distance gives rise to related inferences about those visual targets (size and weight). These results deepen and broaden Construal Level Theory with practical implications for how people reason about the physical properties of objects - including but not limited to their physical distance., (© 2023. The Psychonomic Society, Inc.)

In an integral imaging (II) display system, the self-adjustment ability of the human eye can result in blurry observations when viewing 3D targets outside the focal plane within a specific range. This can impact the overall imaging quality of the II system. This research examines the visual characteristics of the human eye and analyzes the path of light from a point source to the eye in the process of capturing and reconstructing the light field. Then, an overall depth of field (DOF) model of II is derived based on the human visual system (HVS). On this basis, an II system based on the human visual distance (HVD) perception model is proposed, and an interactive II display system is constructed. The experimental results confirm the effectiveness of the proposed method. The display system improves the viewing distance range, enhances spatial resolution and provides better stereoscopic display effects. When comparing our method with three other methods, it is clear that our approach produces better results in optical experiments and objective evaluations: the cumulative probability of blur detection (CPBD) value is 38.73%, the structural similarity index (SSIM) value is 86.56%, and the peak signal-to-noise ratio (PSNR) value is 31.12. These values align with subjective evaluations based on the characteristics of the human visual system.

Monocular blindness impairs visual depth perception, yet patients seldom report difficulties in targeted actions like reaching, walking, or driving. We hypothesized that by utilizing monocular depth information and calibrating actions with haptic feedback, monocular patients can perceive egocentric distance and perform targeted actions. We compared targeted reaching in monocular patients, monocular-viewing, and binocular-viewing normal controls. Sixty observers reached either a far or a near target, calibrating reaches to the near target with accurate or false feedback while leaving reaches to the far target uncalibrated. Reaching accuracy and precision were analyzed. Results indicated no difference in reaching accuracy between monocular patients and normal controls; all groups initially underestimated distances before until calibration. Monocular patients responded to calibration sensitively, achieving accuracy in calibrated reaches and generalizing this effect to uncalibrated distances. Thus, with monocular depth information and haptic feedback, monocular patients could perceive distance and accomplish targeted reaching., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

When humans walk, it is important for them to have some measure of the distance they have traveled. Typically, many cues from different modalities are available, as humans perceive both the environment around them (for example, through vision and haptics) and their own walking. Here, we investigate the contribution of visual cues and nonvisual self-motion cues to distance reproduction when walking on a treadmill through a virtual environment by separately manipulating the speed of a treadmill belt and of the virtual environment. Using mobile eye tracking, we also investigate how our participants sampled the visual information through gaze. We show that, as predicted, both modalities affected how participants ( N = 28) reproduced a distance. Participants weighed nonvisual self-motion cues more strongly than visual cues, corresponding also to their respective reliabilities, but with some interindividual variability. Those who looked more toward those parts of the visual scene that contained cues to speed and distance tended also to weigh visual information more strongly, although this correlation was nonsignificant, and participants generally directed their gaze toward visually informative areas of the scene less than expected. As measured by motion capture, participants adjusted their gait patterns to the treadmill speed but not to walked distance. In sum, we show in a naturalistic virtual environment how humans use different sensory modalities when reproducing distances and how the use of these cues differs between participants and depends on information sampling. NEW & NOTEWORTHY Combining virtual reality with treadmill walking, we measured the relative importance of visual cues and nonvisual self-motion cues for distance reproduction. Participants used both cues but put more weight on self-motion; weight on visual cues had a trend to correlate with looking at visually informative areas. Participants overshot distances, especially when self-motion was slow; they adjusted steps to self-motion cues but not to visual cues. Our work thus quantifies the multimodal contributions to distance reproduction.

The debate surrounding the advantages of binocular versus monocular vision has persisted for decades. This study aimed to investigate whether individuals with monocular vision loss could accurately and precisely perceive large egocentric distances in real-world environments, under natural viewing conditions, comparable to those with normal vision. A total of 49 participants took part in the study, divided into three groups based on their viewing conditions. Two experiments were conducted to assess the accuracy and precision of estimating egocentric distances to visual targets and the coordination of actions during blind walking. In Experiment 1, participants were positioned in both a hallway and a large open field, tasked with judging the midpoint of self-to-target distances spanning from 5 to 30 m. Experiment 2 involved a blind walking task, where participants attempted to walk towards the same targets without visual or environmental feedback at an unusually rapid pace. The findings revealed that perceptual accuracy and precision were primarily influenced by the environmental context, motion condition, and target distance, rather than the visual conditions. Surprisingly, individuals with monocular vision loss demonstrated comparable accuracy and precision in perceiving egocentric distances to that of individuals with normal vision., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Research on the perception of interpersonal distance has shown the existence of an asymmetry effect which depends on the reference point of the estimation: the distance from oneself to others can be perceived as longer or shorter than the distance from others to oneself. The mechanism underlying this asymmetric effect is related to the object's cognitive salience. The self often functions as a habitual reference point and therefore one's own salience may be higher than that of other objects. In this case, an egocentric asymmetry effect appears with a perceived shorter distance from others to oneself. However, if others are more salient than oneself, then the reverse can happen (allocentric asymmetry effect). The present work investigates if asymmetry in self-other(s) distance perception changes when the other is a social robot. An experiment was conducted with 174 participants who were asked to estimate the distance between themselves and both robotic and human assistants on a schematic map of a hospital emergency room (between-subjects design). With robust ANOVA, the results showed that the participants felt closer to the human assistant than to the robot, notably when the person served as the estimation reference point. Perceived distances to the social robot were not significantly distorted. If a rather allocentric effect with the human assistant might reflect an affiliation goal on the part of the participants, the absence of effect with the social robot forces us to reconsider its humanization. This could nevertheless reflect a purely mechanical and utilitarian conception of it., Competing Interests: We have no known conflict of interest to disclose.

Humans can use visual motion to estimate the distance they have traveled. In static environments, optic flow generated by self-motion provides a pattern of expanding motion that is used for the estimation of travel distance. When the environment is populated by other people, their biological motion destroys the one-to-on correspondence between optic flow and travel distance. We investigated how observers estimate travel distance in a crowded environment. In three conditions, we simulated self-motion through a crowd of standing, approaching, or leading point-light walkers. For a standing crowd, optic flow is a veridical signal for distance perception. For an approaching crowd, the visual motion is the sum of the self-motion-induced optic flow and the optic flow produced by the approaching walkers. If only optic flow were to be used, travel distance estimates would be too high because of the approaching direction of the crowd toward the observer. If, on the other hand, cues from biological motion could be used to estimate the speed of the crowd, then the excessive optic from the approaching crowd flow might be compensated. In the leading crowd condition, in which walkers of the crowd keep their distance from the observer as they walk along with the observer, no optic flow is produced. In this condition, travel distance estimation would have to rely solely on biological motion information. We found that distance estimation was quite similar across these three conditions. This suggests that biological motion information can be used (a) to compensate for excessive optic flow in the approaching crowd condition and (b) to generate distance information in the leading crowd condition.

Orthodontists have seen their practices evolve from estimating distances on plaster models to estimating distances on non-immersive virtual models. However, if the estimation of distance using real models can generate errors (compared to the real distance measured using tools), which remains acceptable from a clinical point of view, is this also the case for distance estimation performed on digital models? To answer this question, 50 orthodontists (31 women and 19 men) with an average age of 36 years (σ = 12.84; min = 23; max = 63) participated in an experiment consisting of estimating 3 types of distances (mandibular crowding, inter-canine distance, and inter-molar distance) on 6 dental models, including 3 real and 3 virtual models. Moreover, these models were of three different levels of complexity (easy, medium, and difficult). The results showed that, overall, the distances were overestimated (compared to the distance measured using an instrument) regardless of the situation (estimates on real or virtual models), but this overestimation was greater for the virtual models than for the real models. In addition, the mental load associated with the estimation tasks was considered by practitioners to be greater for the estimation tasks performed virtually compared to the same tasks performed on plaster models. Finally, when the estimation task was more complex, the number of estimation errors decreased in both the real and virtual situations, which could be related to the greater number of therapeutic issues associated with more complex models.

This paper proposes to analyse user experience using two different immersive device categories: a cave automatic virtual environment (CAVE) and a head-mounted display (HMD). While most past studies focused on one of these devices to characterize user experience, we propose to fill the gap in comparative studies by conducting investigations using both devices, considering the same application, method and analysis. Through this study, we want to highlight the differences in user experience induced when using either one of these technologies in terms of visualization and interaction. We performed two experiments, each focusing on a specific aspect of the devices employed. The first one is related to distance perception when walking and the possible influence of the HMD's weight, which does not occur with CAVE systems as they do not require wearing any heavy equipment. Past studies found that weight may impact distance perception. Several walking distances were considered. Results revealed that the HMD's weight does not induce significant differences over short distances (above three meters). In the second experiment, we focused on distance perception over short distances. We considered that the HMD's screen being closer to the user's eyes than in CAVE systems might induce substantial distance perception differences, especially for short-distance interaction. We designed a task in which users had to move an object from one place to another at several distances using the CAVE and an HMD. Results revealed significant underestimation compared to reality as in past work, but no significant differences between the immersive devices. These results provide a better understanding of the differences between the two emblematic virtual reality displays., Competing Interests: Conflict of interestThe authors declare that they have no conflict of interest., (© The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature 2023, Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.)

To benefit from virtual reality (VR) as a complementary tool for training, coaches must determine the proper tools and variables for tracking sports performance. We explored the basketball shooting at several scales (basket-ball, ball-player, and player systems) by monitoring success-rate, and ball and body kinematics. We measured how these scales of analysis allowed tracking players' expertise and perceptual sensitivity to basket distance. Experienced and novice players were instructed to naturally throw and swish an instrumented ball in a stereoscopically rendered virtual basket. We challenged their perceptual-motor systems by manipulating the distance of the virtual basket while keeping the surrounding environment unchanged. The success-rate accounted for the players' shooting adjustments to the manipulation of basket distance and allowed tracking their expertise. Ball kinematics also reflected the manipulation of distance and allowed detecting gender, but did not reflect the players' expertise. Finally, body kinematics variables did not echo players' adjustments to the distance manipulation but reflected their expertise and gender. The results gained at each scale of analysis are discussed with regard to the simulator's construct, biomechanical, and psychological fidelity., (© 2022 The Authors. Scandinavian Journal of Medicine & Science In Sports published by John Wiley & Sons Ltd.)

Tactile distance perception is influenced by stimulus orientation. On the hands or face, effects of orientation may originate from the mostly oval shape of receptive fields (RF) of which the long axis aligns with the proximodistal body axis. As tactile distance estimation relies on the number of RFs between stimuli, their alignment leads to a distortion of perception with distances being perceived as shorter in the proximodistal than the mediolateral body axis. It is however unknown, how physical manipulations such as skin stretch affect distance perception. Participants judged which of two distances aligned with the mediolateral or proximodistal axis on their dorsal dominant hand felt larger in two conditions: without physical manipulation and with proximodistal skin stretch. Distances were perceived shorter in proximodistal direction in both the nonstretch and the stretch condition, which was significantly pronounced in the stretch condition. Skin stretch led to perception of tactile distances as smaller, possibly related to the removal of afferent nerve endings and corresponding somatosensory RFs in the same external reference frame between the two touches. Though skin stretch is represented centrally, our results likely show that no correctional top-down mechanism corrects for skin stretch when estimating tactile distances. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Decades of research have shown that absolute egocentric distance is underestimated in virtual environments (VEs) when compared with the real world. This finding has implications on the use of VEs for applications that require an accurate sense of absolute scale. Fortunately, this underperception of scale can be attenuated by several factors, making perception more similar to (but still not the same as) that of the real world. Here, we examine these factors as two categories: (i) experience inherent to the observer, and (ii) characteristics inherent to the display technology. We analyse how these factors influence the sources of information for absolute distance perception with the goal of understanding how the scale of virtual spaces is calibrated. We identify six types of cues that change with these approaches, contributing both to a theoretical understanding of depth perception in VEs and a call for future research that can benefit from changing technologies. This article is part of the theme issue 'New approaches to 3D vision'.

The promise of virtual reality (VR) as a tool for perceptual and cognitive research rests on the assumption that perception in virtual environments generalizes to the real world. Here, we conducted two experiments to compare size and distance perception between VR and physical reality (Maltz et al . 2021 J. Vis. 21 , 1-18). In experiment 1, we used VR to present dice and Rubik's cubes at their typical sizes or reversed sizes at distances that maintained a constant visual angle. After viewing the stimuli binocularly (to provide vergence and disparity information) or monocularly, participants manually estimated perceived size and distance. Unlike physical reality, where participants relied less on familiar size and more on presented size during binocular versus monocular viewing, in VR participants relied heavily on familiar size regardless of the availability of binocular cues. In experiment 2, we demonstrated that the effects in VR generalized to other stimuli and to a higher quality VR headset. These results suggest that the use of binocular cues and familiar size differs substantially between virtual and physical reality. A deeper understanding of perceptual differences is necessary before assuming that research outcomes from VR will generalize to the real world. This article is part of a discussion meeting issue 'New approaches to 3D vision'.

An experiment evaluated the ability of 30 younger and older adults to visually judge object size under three conditions: (1) full cue, (2) in the dark, with linear perspective, and (3) in complete darkness. Each observer made repeated judgments for the same square stimuli (the task was to adjust a separation until it matched the perceived size of the squares), enabling an evaluation of precision as well as accuracy. The judgments were just as accurate in the dark with linear perspective condition as in the full cue condition, indicating that linear perspective serves as an important source of optical information to support the perception of object size). In contrast, in complete darkness (where linear perspective information was unavailable), the accuracy of the observers' judgments was poor. Finally, there was no difference in either the accuracy or the precision of the observers' judgments between the two age groups, despite the fact that the older adults were more than 50 years older than the younger adults (mean age of the younger and older adults was 22.3 and 74.1 years, respectively). The ability to visually perceive object size is well maintained with increasing age, unlike a number of other important visual abilities., (© 2022. The Author(s).)

The 11th-century Arab scholar, Ibn al-Haytham, in his Optics , offers a detailed, rigorous, empirically oriented explanation of distance perception that may be the first essentially modern, scientific theory of distance perception. Based on carefully described experiments, he argues that for distance to be perceived accurately: (1) the distance must lie along a continuous surface such as the ground; (2) the continuous surface must be visible; (3) the magnitudes of distances along the surface must be perceived and calibrated through bodily interaction (walking and reaching) with them; and finally (4) the distance must be moderate. Al-Haytham's work reached Europe early in the 13th century, and his was the dominant theory of distance perception there for about 400 years. It was superseded early in the 17th century by a theory, based on cues such as convergence and accommodation, of distance seen through empty, mathematized space. Around 1950, an explanation of distance perception strikingly like that of al-Haytham was independently developed by J. J. Gibson, who called his theory the "ground theory" of space perception., Competing Interests: Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s) 2022.)

When navigating a straight path, perceived travel time and perceived traveled distance are linked via movement speed. Behavioral studies have revealed systematic interferences between the perception of travel time and distance, but the role of neuronal representations of movement speed for these effects has not been addressed to date. Using a combined fMRI-behavioral paradigm, we investigate the neuronal representations that underlie cross-dimensional interferences between travel time and traveled distance. Participants underwent fMRI while experiencing visual forward movements for either a short or a long duration, and covering either a short or a long distance. At the behavioral level, we found bi-directional interference effects between time and distance perception, which was correlated with greater representational similarity in speed-sensitive brain regions. The strength of the distance-on-time effect scaled with representational similarity in the left human middle temporal complex (hMT+), and the strength of the time-on-distance effect scaled with representational similarity in the right intraparietal sulcus (IPS). In accordance with the idea that the interference is mediated by the perception of speed, distance-on-time and time-on-distance effects were of opposing directions. Increases in traveled distance led to increases in perceived travel time, while increases in travel time led to decreases in perceived traveled distance. Together, these findings support the view that cross-dimensional interference effects between travel time and traveled distance are mediated by neuronal representations of movement speed., Competing Interests: Declaration of Competing Interest The authors declare no competing financial interests., (Copyright © 2022. Published by Elsevier Inc.)

This study aimed to evaluate the precision, accuracy, and reliability of the common measurement methods for collecting comfort and reachability distances. Four measurement methods were applied in the study: real-life measurement, virtual reality (VR) simulation, the media method, and the paper-and-pencil test. Forty participants were recruited, who were required to determine their comfort and reachability distances when approached by, or actively approaching, confederates under the four methods. The relative error magnitude and mean absolute difference were used to evaluate the precision and accuracy of the methods, respectively. Then, intraclass correlation coefficients were applied to evaluate the reliability of the methods. The ANOVA results showed that the confederate's gender, method, and pattern all had significant effects on the comfort and reachability distances. The distance obtained by the paper-and-pencil test was the smallest, while the distance measured by the media method was larger. The real-life measurement had high reliability, but its precision performance was worse than that of both the VR simulation and the active media method. The VR simulation had the best precision and reliability, while the measurement value tended to be overestimated. The media method in the passive pattern showed the worst precision, accuracy, and reliability performance among the four methods. The active media method performed well except for accuracy when collecting distance data. The paper-and-pencil test showed erroneous results regarding the precision and reliability performance. These findings provide scientific reference suggestions for the selection of measuring methods for collecting comfort and reachability distances., (© 2021. The Psychonomic Society, Inc.)

Mothers and infants co-regulate their distance from one another at home. Continuous, naturalistic home observations of the changes in mother-infant distance were carried out in Japan and Scotland during infant ages of 0-1, 6-7, and 12-13 months. This study examined mutual distance-increasing and distance-reducing behaviours, referred to as parent-infant 'centrifugalism' and 'centripetalism'. Cultural differences emerged in the modes of mother-infant distance co-regulation. Scottish mothers were more active in initiating contact and leaving infants alone to sleep, whereas Japanese mothers showed stronger infant-centredness by maintaining physical contact with infants when they fell asleep and reacting to their crying when they woke up. Age differences were found relating to decrease in sleep and increase in object play in the middle of the first year, which resulted in more separation within a 0.5 m distance at 6-7 months, a compromise between closeness and distancing between mothers and awake infants. Cultural and age differences in the co-regulation of mother-infant distance were discussed in relation to the development of locomotion, object play, and intention-reading., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Reaches guided using monocular versus binocular vision have been found to be equally fast and accurate only when optical texture was available projected from a support surface across which the reach was performed. We now investigate what property of optical texture elements is used to perceive relative distance: image width, image height, or image shape. Participants performed reaches to match target distances. Targets appeared on a textured surface on the left and participants reached to place their hand at target distance along a surface on the right. A perturbation discriminated which texture property was being used. The righthand surface was higher than the lefthand one by either 2, 4 or 6 cm. Participants should overshoot if they matched texture image width at the target, undershoot if they matched image shape, and undershoot far distances and, depending on the overall eye height, overshoot near distances if they matched image height. In Experiment 1, participants reached by moving a joystick to control a hand avatar in a virtual environment display. Their eye height was 15 cm. For each texture property, distances were predicted from the viewing geometry. Results ruled out image width in favor of image height or shape. In Experiment 2, participants at a 50 cm eye height reached in an actual environment with the same manipulations. Results supported use of image shape (or foreshortening), consistent with findings of texture properties used in slant perception. We discuss implications for models of visually guided reaching., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Auditory distance perception is important to virtual sound production and is affected by many factors. In order to investigate the effect of the visual cue on auditory distance perception and the best auditory distance perception in the existence of virtual sound source, experiments on the effect of visual cue on distance perception and the best auditory distance perception were conducted, respectively. The results of the first experiment showed that there was no obvious difference between the auditory distance perception in the existence and absence of virtual sound source, but visual cue can decrease the fluctuation of the perception. From the best auditory distance perception experiment, the attenuating SPL of the initial sound signal that made the subjects perceive the best auditory distance in the existence of virtual sound source at the distance of 4m, 6m, 8m, 10m, and 12m was measured, respectively, and compared the difference of attenuating SPL between experiment measurement and theoretical calculation., Competing Interests: The authors declare that there are no conflicts of interest regarding the publication of this paper., (Copyright © 2022 Hui Song and Ke Ma.)

Background: Bodily state is theorised to play a role in perceptual scaling of the environment, whereby low bodily capacity shifts visuospatial perception, with distances appearing farther and hills steeper, and the opposite seen for high bodily capacity. This may play a protective role, where perceptual scaling discourages engaging with the environment when capacity is low., Methodology: Our protocol was pre-registered via Open Science Framework (https://osf.io/6zya5/) with all amendments to the protocol tracked. We performed a systematic review and meta-analysis examining the role of bodily state/capacity on spatial perception measures of the environment. Databases (Medline, PsychINFO, Scopus, Embase, and Emcare) and grey literature were searched systematically, inclusive to 26/8/21. All studies were assessed using a customised Risk of Bias form. Standard mean differences and 95% CIs were calculated via meta-analysis using a random-effects model., Results: A total of 8,034 studies were identified from the systematic search. Of these, 68 experiments (3,195 participants) met eligibility and were included in the review. These were grouped into the following categories: fatigue; pain; age; embodiment; body size/body paty size; glucose levels; fitness; and interoception, and interoceptive accuracy. We found low level evidence (limited studies, high risk of bias) for the effect of bodily state on spatial perception. There was consistent evidence that both glucose manipulations and age influence spatial perception of distances and hills in a hypothesised direction (lower capacity associated with increased distance and hill steepness). Mixed evidence exists for the influence of external loads, embodiment, body/body-part size manipulations, pain, and interoceptive accuracy. Evidence for fitness and/or fatigue influencing spatial perception was conflicting; notably, methodological flaws with fitness and fatigue paradigms and heterogenous spatial perception measures may underlie null/conflicting results., Conclusion: We found limited evidence for bodily state influencing spatial perception of the environment. That all studies had high risk of bias makes conclusions about reported effects reflecting actual perceptual shifts ( vs merely reflecting experimental demands or error due to inadequate study design) pre-emptive. Rigorous evaluation is needed to determine whether reported effects reflect more than bias ( e.g ., experimental demands, inadequate blinding). Future work using reliable measures of spatial perception, comprehensive evaluation of relevant confounders, and methodologically robust (and experimentally confirmed) bodily state experimental paradigms is warranted., Competing Interests: Felicity A. Braithwaite and Tasha R. Stanton have received speaker fees for providing lectures related to pain and rehabilitation. Brendan Mouatt receives renumeration from The Knowledge Exchange for provision of continuing professional development workshops related to pain and exercise rehabilitation. All other authors report no conflicts of interest., (© 2022 MacIntyre et al.)

The ability to visually perceive distances in depth was evaluated in two experiments. In both experiments, the observers were required to bisect a distance interval oriented in depth (8 m total extent in Experiment 1 and 7 m in Experiment 2). The purpose of Experiment 1 was to examine the effects of environmental context (indoors in the dark, indoors in the light, and outdoors) and monocular versus binocular viewing. The purpose of Experiment 2 was to manipulate linear perspective to determine its importance for perceiving depth interval magnitudes. In the outdoor environment, the observers' bisection judgments indicated perceptual compression of farther distances similar to that obtained in many previous studies. In contrast, the observers' judgments in the indoor lighted environment were consistent with the perceptual expansion of farther distances. There was also a beneficial effect of binocular viewing upon the precision of the observers' repeated judgments, but the size of this effect was large only within the dark environment. Finally, linear perspective was found to significantly modulate the observers' bisection judgments such that they became accurate only when perspective was available., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Self-motion perception refers to the ability to perceive how the body is moving through the environment. Perception of self-motion has been shown to depend upon the locomotor action patterns used to move the body through the environment. Two separate lines of enquiry have led to the establishment of two distinct theories regarding this effect. One theory has proposed that distances travelled during locomotion are perceived via higher order perceptual variables detected by the haptic perceptual system. This theory proposes that two higher order haptic perceptual variables exist, and that the implication of one of these variables depends upon the type of gait pattern that is used. A second theory proposes that self-motion is perceived via a higher order perceptual variable termed multimodally specified energy expenditure (MSEE). This theory proposes that the effect of locomotor actions patterns upon self-motion perception is related to changes in the metabolic cost of locomotion per unit of perceptually specified traversed distance. Here, we test the hypothesis that the development of these distinct theories is the result of different choices in methodology. The theory of gait type has been developed based largely on the results of homing tasks, whereas the effect of MSEE has been developed based on the results of distance matching tasks. Here we test the hypothesis that the seemly innocuous change in experimental design from using a homing task to using a distance matching task changes the type of perceptual variables implicated in self-motion perception. To test this hypothesis, we closely replicated a recent study of the effect of gait type in all details bar one-we investigated a distance matching task rather than a homing task. As hypothesized, this change yielded results consistent with the predictions of MSEE, and distinct from gait type. We further show that, unlike the effect of gait type, the effect of MSEE is unaffected by the availability of vision. In sum, our findings support the existence of two distinct types of higher order perceptual variables in self-motion perception. We discuss the roles of these two types of perceptual variables in supporting effective human wayfinding., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The distance of sound sources relative to the body can be estimated using acoustic level and direct-to-reverberant ratio cues. However, the ability to do this may differ for sounds that are in front compared to behind the listener. One reason for this is that vision, which plays an important role in calibrating auditory distance cues early in life, is unavailable for rear space. Furthermore, the filtering of sounds by the pinnae differs if they originate from the front compared to the back. We investigated auditory distance discrimination in front and rear space by comparing performance for auditory spatial bisection of distance and minimum audible distance discrimination (MADD) tasks. In the bisection task, participants heard three successive bursts of noise at three different distances and indicated whether the second sound (probe) was closer in space to the first or third sound (references). In the MADD task, participants reported which of two successive sounds was closer. An analysis of variance with factors task and region of space showed worse performance for rear than for front space, but no significant interaction between task and region of space. For the bisection task, the point of subjective equality (PSE) was slightly biased towards the body, but the absolute magnitude of the PSE did not differ between front and rear space. These results are consistent with the hypothesis that visual information is important in calibrating the auditory representation of front space in distance early in life., Competing Interests: Declarations of Competing Interest None., (Copyright © 2022. Published by Elsevier B.V.)

Recent studies claim that estimating the magnitude of the spatial and temporal aspects of one's self-motion shows similar characteristics, suggesting shared processing mechanisms between these two dimensions. While the estimation of other magnitude dimensions, such as size, number, and duration, exhibits negative aftereffects after prolonged exposure to the stimulus, it remains to be elucidated whether this could occur similarly in the estimation of the distance travelled and time elapsed during one's self-motion. We sought to fill this gap by examining the effects of adaptation on distance and time estimation using a virtual navigation task. We found that a negative aftereffect occurred in the distance reproduction task after repeated exposure to self-motion with a fixed travel distance. No such aftereffect occurred in the time reproduction task after repeated exposure to self-motion with a fixed elapsed time. Further, the aftereffect in distance reproduction occurred only when the distance of the adapting stimulus was fixed, suggesting that it did not reflect adaptation to time, which varied with distance. The estimation of spatial and temporal aspects of self-motion is thus processed by partially separable mechanisms, with the distance estimation being similar to the estimation of other magnitude dimensions., Competing Interests: Declaration of Conflicting Interests: The authors declare no competing financial conflicts., (© The Author(s) 2022.)

Past work has suggested that perception of object distances in natural scenes depends on the environmental surroundings, even when the physical object distance remains constant. The cue bases for such effects remain unclear and are difficult to study systematically in real-world settings, given the challenges in manipulating large environmental features reliably and efficiently. Here, we used rendered scenes and crowdsourced data collection to address these challenges. In 4 experiments involving 452 participants, we investigated the effect of room width and depth on egocentric distance judgments. Targets were placed at distances of 2-37 meters in rendered rooms that varied in width (1.5-40 meters) and depth (6-40 meters). We found large and reliable effects of room width: Average judgments for the farthest targets in a 40-meter-wide room were between 16-33% larger than for the same target distances seen in a 1.5-meter-wide hallway. Egocentric distance cues and focal length were constant across room widths, highlighting the role of environmental context in judging distances in natural scenes. Obscuring the fine-grained ground texture, per se, is not primarily responsible for the width effect, nor does linear perspective play a strong role. However, distance judgments tended to decrease when doors and/or walls obscured more distant regions of the scene. We discuss how environmental features may be used to calibrate relative distance cues for egocentric distance judgments., Competing Interests: The authors have declared that no competing interests exist.

In recent years, Virtual Reality (VR) Head-Mounted Displays (HMD) have been used to provide an immersive, first-person view in real-time for the remote-control of Unmanned Ground Vehicles (UGV). One critical issue is that it is challenging to perceive the distance of obstacles surrounding the vehicle from 2D views in the HMD, which deteriorates the control of UGV. Conventional distance indicators used in HMD take up screen space which leads clutter on the display and can further reduce situation awareness of the physical environment. To address the issue, in this paper we propose off-screen in-device feedback using vibro-tactile and/or light-visual cues to provide real-time distance information for the remote control of UGV. Results from a study show a significantly better performance with either feedback type, reduced workload and improved usability in a driving task that requires continuous perception of the distance between the UGV and its environmental objects or obstacles. Our findings show a solid case for in-device vibro-tactile and/or light-visual feedback to support remote operation of UGVs that highly relies on distance perception of objects.

Here, we investigate how body orientation relative to gravity affects the perceived size of visual targets. When in virtual reality, participants judged the size of a visual target projected at simulated distances of between 2 and 10 m and compared it to a physical reference length held in their hands while they were standing or lying prone or supine. Participants needed to make the visual size of the target 5.4% larger when supine and 10.1% larger when prone, compared to when they were in an upright position to perceive that it matched the physical reference length. Needing to make the target larger when lying compared to when standing suggests some not mutually exclusive possibilities. It may be that while tilted participants perceived the targets as smaller than when they were upright. It may be that participants perceived the targets as being closer while tilted compared to when upright. It may also be that participants perceived the physical reference length as longer while tilted. Misperceiving objects as larger and/or closer when lying may provide a survival benefit while in such a vulnerable position.