Interpersonal Distance in Immersive Virtual Environments

Evaluating Human Movement Coordination During Immersive Walking in a Virtual Crowd

This paper describes our investigation on how participants coordinate movement behavior in relation to a virtual crowd that surrounds them while immersed in a virtual environment. The participants were immersed in a virtual metropolitan city and were instructed to cross the road and reach the opposite sidewalk. The participants performed the task ten times. The virtual crowd that surrounded them was scripted to move in the same direction. During the experiment, several measurements were obtained to evaluate human movement coordination. Moreover, the time and direction in which the participants started moving toward the opposite sidewalk were also captured. These data were later used to initialize the parameters of simulated characters that were scripted to become part of the virtual crowd. Measurements were extracted from the simulated characters and used as a baseline to evaluate the movement coordination of the participants. By analyzing the data, significant differences between the movement behaviors of the participants and the simulated characters were found. However, simple linear regression analyses indicated that the movement behavior of participants was moderately associated with the simulated characters' movements when performing a locomotive task within a virtual crowd population. This study can be considered as a baseline for further research that evaluates the movement coordination of participants during human-virtual-crowd interactions using measurements obtained by the simulated characters.

An Investigation Into Interpersonal and Peripersonal Spaces of Chinese People for Different Directions and Genders

This study explores the interpersonal space (IPS) and peripersonal space (PPS) of Chinese people and evaluates the relationship between the two spaces for different directions and genders. Seventy-one participants were recruited for this study. Participants were required to determine their IPS in eight directions (0°, 45°, 90°, 135°, 180°, 225°, 270°, 315°) when approached by male or female confederates in the comfort distance task. Each participant was also asked to judge their PPS in five directions (0°, 45°, 90°, 270°, 315°) following the same procedure. Results showed that their IPS was significantly influenced by direction (p < 0.05), with the largest distance in the front (0°) and the closest distance in the rear (135°, 180°, 225°), indicating non-circular IPS among Chinese subjects. Moreover, the PPS on the right side (90°) was larger than in other directions (0°, 45°, 270°, 315°). Participants maintained larger IPS than PPS in the front, but the IPS was closer than PPS on the right and left sides. When facing a female confederate, larger IPS was preferred than PPS, whereas the opposite held true when facing a male confederate. Comparison of participants’ arm length and PPS showed that the reachability distance was overestimated in the front but underestimated laterally. The findings of this study can be applied to environmental design, space utilization, and social interaction.

Measuring Alliance Toward Embodied Virtual Therapists in the Era of Automated Treatments With the Virtual Therapist Alliance Scale (VTAS): Development and Psychometric Evaluation

BACKGROUND

Automated virtual reality exposure therapies (VRETs) are self-help treatments conducted by oneself and supported by a virtual therapist embodied visually and/or with audio feedback. This simulates many of the nonspecific relational elements and common factors present in face-to-face therapy and may be a means of improving adherence to and efficacy of self-guided treatments. However, little is known about alliance toward the virtual therapist, despite alliance being an important predictor of treatment outcome.

OBJECTIVE

In this study, we aimed to evaluate the first alliance instrument developed for use with embodied virtual therapists in an automated treatment format-the Virtual Therapist Alliance Scale (VTAS)-by (1) assessing its psychometric properties, (2) verifying the dimensionality of the scale, and (3) determining the predictive ability of the scale with treatment outcome.

METHODS

A psychometric evaluation and exploratory factor analysis of the VTAS was conducted using data from two samples of spider-fearful patients treated with VRET and the help of an embodied, voice-based virtual therapist (n=70). Multiple regression models and bivariate correlations were used to assess the VTAS relationship with treatment outcome, according to self-reported fear and convergence with presence and user-friendliness process measures.

RESULTS

The VTAS showed a sound two-factor solution composed of a primary factor covering task, goal, and copresence; adequate internal consistency; and good convergent validity, including moderate correlation (r=.310, P=.01) with outcomes over follow-up.

CONCLUSIONS

These preliminary results suggest that alliance toward a virtual therapist is a significant predictor of treatment outcome, favors the importance of a task-goal over bond-factor, and should be explored in studies with larger sample sizes and in additional forms of embodiment.

Questionnaire Measures and Physiological Correlates of Presence: A Systematic Review

The published literature has produced several definitions for the sense of presence in a simulated environment, as well as various methods for measuring it. The variety of conceptualizations makes it difficult for researchers to interpret, compare, and evaluate the presence ratings obtained from individual studies. Presence has been measured by employing questionnaires, physiological indices, behavioral feedbacks, and interviews. A systematic literature review was conducted to provide insight into the definitions and measurements of presence in studies from 2002 to 2019, with a focus on questionnaires and physiological measures. The review showed that scholars had introduced various definitions of presence that often originate from different theoretical standpoints and that this has produced a multitude of different questionnaires that aim to measure presence. At the same time, physiological studies that investigate the physiological correlates of the sense of presence have often shown ambiguous results or have not been replicated. Most of the scholars have preferred the use of questionnaires, with Witmer and Singer's Presence Questionnaire being the most prevalent. Among the physiological measures, electroencephalography was the most frequently used. The conclusions of the present review aim to stimulate future structured efforts to standardize the use of the construct of presence, as well as inspire the replication of the findings reported in the published literature.

Tracing Physical Behavior in Virtual Reality: A Narrative Review of Applications to Social Psychology

Virtual reality (VR) offers unique benefits to social psychological research, including a high degree of experimental control alongside strong ecological validity, a capacity to manipulate any variable of interest, and an ability to trace the physical, nonverbal behavior of the user in a very fine-grained and automated manner. VR improves upon traditional behavioral measurement techniques (e.g., observation and coding) on several fronts as data collection is covert, continuous, passive, and occurs within a controlled context. The current review synthesizes extant methods for tracing physical behavior in VR, such as gaze tracking and interpersonal distance measurement, and describes how researchers have applied these methods to understand important phenomena within the context of social psychology. To date, primary areas of application have included the assessment of social approach and avoidance, social evaluation and bias, and engagement. The limitations of behavioral tracing methods in VR, as well as future directions for their continued application and extension, are discussed. This narrative review equips readers with a thorough understanding of behavioral tracing methods that can be implemented in VR, their benefits and drawbacks, the insight they may offer into social processes, and future avenues of work for applying emergent technologies to research questions in social psychology.

F-Formations for Social Interaction in Simulation Using Virtual Agents and Mobile Robotic Telepresence Systems

F-formations are a set of possible patterns in which groups of people tend to spatially organize themselves while engaging in social interactions. In this paper, we study the behavior of teleoperators of mobile robotic telepresence systems to determine whether they adhere to spatial formations when navigating to groups. This work uses a simulated environment in which teleoperators are requested to navigate to different groups of virtual agents. The simulated environment represents a conference lobby scenario where multiple groups of Virtual Agents with varying group sizes are placed in different spatial formations. The task requires teleoperators to navigate a robot to join each group using an egocentric-perspective camera. In a second phase, teleoperators are allowed to evaluate their own performance by reviewing how they navigated the robot from an exocentric perspective. The two important outcomes from this study are, firstly, teleoperators inherently respect F-formations even when operating a mobile robotic telepresence system. Secondly, teleoperators prefer additional support in order to correctly navigate the robot into a preferred position that adheres to F-formations.

Joint Action in a Virtual Environment: Crossing Roads with Risky vs. Safe Human and Agent Partners

This paper examines how people jointly coordinate their decisions and actions with risky vs. safe human and agent road-crossing partners (Fig. 1 ). The task for participants was to physically cross a steady stream of traffic in a large-screen virtual environment without getting hit by a car. The computer-generated (CG) agent was programmed to be either safe (taking only large gaps) or risky (also taking small gaps). The human partners were classified as safe (taking more large gaps) or risky (also taking some small gaps) based on their average gap size selection. We found that participants in all four conditions preferred to cross with their partner. As a consequence, the riskiness of the partner (both human and agent) influenced the riskiness of participants' gap choices. We also found that participants tightly synchronized their movement with both human and agent partners. The largest differences in performance between those paired with agent vs. human partners occurred on trials when participants crossed different gaps than their partners. This study demonstrates the potential for studying how people interact with CG agents when performing whole-body joint actions using large-screen immersive virtual environments.

"Science Manipulates the Things and Lives in Them": Reconsidering Approach-Avoidance Operationalization Through a Grounded Cognition Perspective

Approach and avoidance orientations are key elements of adaptive regulation at the evaluation-behavior interface. On the one hand, continuous evaluations of the world fuel approach-avoidance reactions as a function of the individual's immediate environment. On the other hand, in turn these individual-environment adjustments influence evaluations. A grounded perspective of social cognition, placing the sensorimotor aspects of individual-environment interactions at the core of cognition, has much to offer for the understanding of evaluative processes. Despite the growing enthusiasm for a grounded view of cognition and action in the approach-avoidance literature, its core principles are seldom reflected at the operationalization level. In this paper, we relied on the insights of a grounded perspective to propose more encompassing operationalizations of approach-avoidance orientations and investigate their influence on evaluations. Across six studies, we varied the approach-avoidance operationalizations (upper-body incline, upper-body posture and walking steps) and incrementally considered the grounded assumptions. We failed to obtain the theorized positive effect of approach (as compared to avoidance) on evaluations. Interestingly, further exploratory analyses on two studies conducted in Virtual Reality suggested that the more participants felt being present in the situation, the more the approach-avoidance ecological actions activated the corresponding neuropsychological systems. We discuss these emergent findings in light of grounded cognition and the notion of feeling of presence.

Virtual social support buffers stress response: An experimental comparison of real-life and virtual support prior to a social stressor

BACKGROUND AND OBJECTIVES

Face-to-face and text-based social support have been shown to attenuate stress responses in past studies. Yet as social interactions increasingly take place online by means of virtual humans, our objective was to examine whether different forms of social support (virtual vs. real) prior to the Trier Social Stress Test (TSST) would also decrease stress. Additionally, the effect on subsequent real-life social behaviors (helping and approach) was evaluated while controlling for affective states and social presence.

METHODS

56 participants were either supported by an avatar, an agent, a real human or received no support before completing the TSST and two subsequent social behavior tasks (pen task and seating task).

RESULTS

Results show no difference in agency regarding social presence. Yet, participants with agent support and no support had significantly higher heart rates during the TSST and reported to be more worried. Also, they were more irritated and showed significantly slower helping reactions (picking up pens).

LIMITATIONS

A limitation to this study is that only emotional verbal and non-verbal support were provided by a stranger. Different forms of support as well as a different source (i.e., a friend) may have a more pronounced effect on stress buffering.

CONCLUSIONS

Virtual social support is as effective as face-to-face support in terms of stress buffering, as long as the recipient has the impression that it is provided by another human (via an avatar). This has wide ranging implications not only for health-related application in prevention and treatment but also for further research.

Phone messages affect the detection of approaching pedestrians in healthy young and older adults immersed in a virtual community environment

Background

Mobile phones are increasingly associated with accidents while walking. Little is known, however, about the impact of phone messaging on the actual perception of other pedestrians. This study aimed to investigate the extent to which the detection of approaching pedestrians is affected by the sensory modality (text or audio) of phone messages in young vs. older adults.

Methods

Eighteen healthy young (24 ± 2.9 years) and 15 older adults (68 ± 4.2 years) performed a phone message deciphering task, an obstacle detection task, and a dual-task condition combining both tasks. Participants were tested while seated and viewing a virtual subway station (VE) in a helmet mounted display. As they were passively moved within the VE one of three virtual pedestrians randomly approached them from the center (0°), right (+40°) or left (+40°). When present, phone message conditions were delivered at obstacle movement onset and presented either as (1) text messages on the screen of a virtual phone or (2) audio messages delivered through earphones. Participants were instructed to press a joystick button as soon as they detected the approaching virtual pedestrian and to report the message content at the end of the trials.

Results

Young and older participants showed delayed obstacle detection times with vs. without text messages. Older adults further showed reduced accuracy of message report for texts compared to audio messages. In both groups, audio messages yielded no difference in obstacle detection time or accuracy of message report compared to the no message condition.

Conclusions

Findings indicate that text messages prolong the detection of approaching pedestrians, suggesting that they compromise safe ambulation in community environments. Older adults, who show larger deteriorations on the obstacle detection and message deciphering tasks, may be at even greater risk of collision. Audio messages could be a safer alternative for on-the-go communication.

Effects of Age on Obstacle Avoidance while Walking and Deciphering Text versus Audio Phone Messages

BACKGROUND

Widely popular among young, and more recently older adults, mobile phones are increasingly used while walking. Knowledge of the impact of phone message modality (e.g., text vs. audio) on the ability to avoid collisions with other pedestrians, however, remains limited.

OBJECTIVES

This study aimed to investigate the extent to which the circumvention of an approaching pedestrian is affected by text versus audio phone messages in healthy young and older adults.

METHOD

Sixteen young (aged 24 ± 3 years) and 14 older adults (aged 68 ± 4.5 years) were tested while walking and viewing a virtual environment depicted as a subway station in a helmet-mounted display. As they walked, one of three virtual humans randomly approached from the center (0°), right (+40°), or left (+40°). Phone messages, when present, were delivered at obstacle displacement onset and presented either as text messages on a virtual phone or as audio messages delivered through earphones. Participants were instructed to avoid collisions with pedestrians and to fully report the message content at the end of trials.

RESULTS

Both groups showed decreased accuracy of message report (AMR), slower walking speed, and more collisions in response to text versus audio messages. Compared to young adults, older adults showed greater reduction in AMR, more collisions, and similar speed adaptation in the presence of text messages. In both age groups, no significant differences in walking speed emerged between the audio message and the no-message condition, but only older adults experienced collisions and reduced AMR with the audio messages. Obstacle clearance and the onset time of avoidance strategy were not affected by message condition.

CONCLUSIONS

Results suggest that coping with text messages while walking leads to greater risk of collision and alters message deciphering accuracy, while audio messages stand out as a safer and more efficient alternative for on-the-go communication. In general, older adults experienced larger motor-cognitive interference than younger adults, resulting in reduced AMR and more collisions without further changes in gait adaptation. Consequently, older adults failed to prioritize their safety when attending to phone messages while walking.

Interpersonal Affordances and Social Dynamics in Collaborative Immersive Virtual Environments: Passing Together Through Apertures

An essential question in understanding how to develop and build collaborative immersive virtual environments (IVEs) is recognizing how people perform actions together. Many actions in the real world require that people act without prior planning, and these actions are executed quite successfully. In this paper, we study the common action of two people passing through an aperture together in both the real world (Experiment 1) and in a distributed, collaborative IVE (Experiment 2). The aperture's width is varied from too narrow to be passable to so wide as to be easily passable by both participants together simultaneously. We do this in the real world for all possible gender-based pairings. In virtual reality, however, there is potential for the gender of the participant and the gender of the self-avatar to be different. We also investigate the joint action for all possible gender-based pairings in the distributed IVE. Results indicated that, in the real world, social dynamics between gendered pairings emerged; male-male pairings refused to concede to one another until absolutely necessary while other pairings did not. Male-female pairings were most likely to provide ample space to one another during passage. These behaviors seemed not to appear in the IVE, and avatar gender across all pairings generated no significant behavioral differences. In addition, participants tended to require wider gaps to allow for passage in the IVE. These findings establish base knowledge of social dynamics and affordance behaviors within multi-user IVEs.

Walking with avatars: Gait-related visual information for following a virtual leader

Dynamic situations, such as interactive sports or walking on a busy street, impose high demands on a person's ability to interact with (others in) its environment (i.e., 'interact-ability'). The current study examined how distance regulation, a fundamental component of these interactions, is mediated by different sources of visual information. Participants were presented with a back and forwards moving virtual leader, which they had to follow by walking back and forwards themselves. We presented the leader in several appearances that differed in the presence of segmental (i.e., relative movements of body segments), cadence-related (i.e., sway and bounce), and global (i.e., optical expansion-compression) information. Results indicated that removing segmental motion information from the virtual leader significantly deteriorated both temporal synchronization and spatial accuracy of the follower to the leader, especially when the movement path of the leader was less regular/predictable. However, no difference was found between cadence-related and global motion information appearances. We argue that regulating distance with others effectively requires a versatile attunement to segmental and global motion information depending on the specific task demands. The results further support the notion that detection of especially segmental information allows for more timely 'anticipatory' tuning to another person's locomotor movements and intentions.

Augmented Reality in the Health Domain: Projecting Spatial Augmented Reality Visualizations on a Perceiver's Body for Health Communication Effects

An experiment is reported that studied the effects of spatial embodiment in augmented reality on medical attitudes about the self. College students (N = 90) viewed public service announcements (PSAs) with overlaid virtual fetuses and X-rayed images of lungs on various interfaces representing embodiment-a two-dimensional screen, a three-dimensional (3D) mannequin, and the participants' bodies (3D). Results indicated that PSA messages with richer embodied interfaces increase the sense of "being there," also known as spatial presence (SP), in sequential order; this leads to increased negative emotion regarding smoking cigarettes and an increased willingness to engage with a cigarette cessation campaign. When the SP mediates the dual model process, only affective attitudes increase the behavioral intention to engage with the campaign.

ParlAmI: A Multimodal Approach for Programming Intelligent Environments

The proliferation of Internet of Things (IoT) devices and services and their integration in intelligent environments creates the need for a simple yet effective way of controlling and communicating with them. Towards such a direction, this work presents ParlAmI, a conversational framework featuring a multimodal chatbot that permits users to create simple “if-then” rules to define the behavior of an intelligent environment. ParlAmI delivers a disembodied conversational agent in the form of a messaging application named MAI, and an embodied conversational agent named nAoMI employing the programmable humanoid robot NAO. This paper describes the requirements and architecture of ParlAmI, the infrastructure of the “Intelligent Home” in which ParlAmI is deployed, the characteristics and functionality of both MAI and nAoMI, and finally presents the findings of a user experience evaluation that was conducted with the participation of sixteen users.

Collaborative Immersive Virtual Environments for Education in Geography

Immersive virtual reality (iVR) devices are rapidly becoming an important part of our lives and forming a new way for people to interact with computers and each other. The impact and consequences of this innovative technology have not yet been satisfactory explored. This empirical study investigated the cognitive and social aspects of collaboration in a shared, immersive virtual reality. A unique application for implementing a collaborative immersive virtual environment (CIVE) was developed by our interdisciplinary team as a software solution for educational purposes, with two scenarios for learning about hypsography, i.e., explanations of contour line principles. Both scenarios allow switching between a usual 2D contour map and a 3D model of the corresponding terrain to increase the intelligibility and clarity of the educational content. Gamification principles were also applied to both scenarios to augment user engagement during the completion of tasks. A qualitative research approach was adopted to obtain a deep insight into the lived experience of users in a CIVE. It was thus possible to form a deep understanding of very new subject matter. Twelve pairs of participants were observed during their CIVE experience and then interviewed either in a semistructured interview or a focus group. Data from these three research techniques were analyzed using interpretative phenomenological analysis, which is research method for studying individual experience. Four superordinate themes—with detailed descriptions of experiences shared by numerous participants—emerged as results from the analysis; we called these (1) Appreciation for having a collaborator, (2) The Surprising “Fun with Maps”, (3) Communication as a challenge, and (4) Cognition in two realities. The findings of the study indicate the importance of the social dimension during education in a virtual environment and the effectiveness of dynamic and interactive 3D visualization.

The experience of virtual reality: are individual differences in mental imagery associated with sense of presence?

The concept of "presence" describes the quality of subjective experience in immersive virtual reality (IVR). Presence refers to a specific state of consciousness: we behave and feel as if we actually were in the virtual world even though we know there is nothing there. In their handbook of Virtual Reality, Burdea and Coiffet (Virtual reality technology, Wiley, New York, 2003) suggested that the experience of presence in IVR would emerge from the combination of three Is: Immersion or capacity to isolate from the external world, Interaction or capacity to naturally exploring the virtual environment, and Imagination or individual aptitudes with mental imagery. So far, several studies have investigated the technological and psychological factors affecting the degree of immersion and interaction. However, no study has explored the relationship between perceived presence and mental imagery. Here we aim at filling this gap through a correlational study comparing self-reports about sense of presence and mental imagery abilities. After experiencing two IVR scenarios (an art gallery and a living room), 142 male and female users were administered with questionnaires assessing the degree of presence (Igroup Presence Questionnaire), the degree of vividness (Vividness of Visual Imagery Questionnaire) and control (Test of Visual Imagery Control) of subjective mental images. Results showed a clear positive correlation between presence and vividness: the higher the vividness of mental images the stronger the reported sense of presence felt in IVR scenarios. Instead, the capacity to control mental imagery showed a weaker association with presence. We may conclude that individual differences in the degree of perceived presence and mental imagery ability are associated.

Oasis: Procedurally Generated Social Virtual Spaces from 3D Scanned Real Spaces

We present Oasis, a novel system for automatically generating immersive and interactive virtual reality environments for single and multiuser experiences. Oasis enables real-walking in the generated virtual environment by capturing indoor scenes in 3D and mapping walkable areas. It makes use of available depth information for recognizing objects in the real environment which are paired with virtual counterparts to leverage the physicality of the real world, for a more immersive virtual experience. Oasis allows co-located and remotely located users to interact seamlessly and walk naturally in a shared virtual environment. Experiencing virtual reality with currently available devices can be cumbersome due to presence of objects and furniture which need to be removed every time the user wishes to use VR. Our approach is new, in that it allows casual users to easily create virtual reality environments in any indoor space without rearranging furniture or requiring specialized equipment, skill or training. We demonstrate our approach to overlay a virtual environment over an existing physical space through fully working single and multiuser systems implemented on a Tango tablet device.

Collision Avoidance With Multiple Walkers: Sequential or Simultaneous Interactions?

Collision avoidance between multiple walkers, such as pedestrians in a crowd, is based on a reciprocal coupling between the walkers with a continuous loop between perception and action. Such interpersonal coordination has previously been studied in the case of dyadic locomotor interactions. However, when walking through a crowd of people, collision avoidance is not restricted to dyadic interactions. We examined how dyadic avoidance (1 vs. 1) compared to triadic avoidance (1 vs. 2). Additionally, we examined how the dynamics of a passable gap between two walkers affected locomotor interactions. To this end, we manipulated the starting formation of two walkers that formed a potentially pass-able gap for the other walker. We analyzed the interactions in terms of the evolution over time of the Minimal Predicted Distance and the Dynamics of the Gap, which both provide information about what action is afforded (i.e., passing in front/behind and the pass-ability of the gap). Results showed that some triadic interactions invited for sequential interactions, resulting in avoidance strategies comparable with dyadic interactions. However, some formations resulted in simultaneous interactions where the dynamics of the pass-ability of the gap revealed that the coordination strategy emerged over time through the bi-directional interactions between all walkers. Future work should address which circumstances invite for simultaneous and which for sequential interactions between multiple walkers. This study contributed toward understanding how collision is avoided between multiple walkers at the level of the local interactions.

A Systematic Review of Social Presence: Definition, Antecedents, and Implications

Social presence, or the feeling of being there with a "real" person, is a crucial component of interactions that take place in virtual reality. This paper reviews the concept, antecedents, and implications of social presence, with a focus on the literature regarding the predictors of social presence. The article begins by exploring the concept of social presence, distinguishing it from two other dimensions of presence-telepresence and self-presence. After establishing the definition of social presence, the article offers a systematic review of 233 separate findings identified from 152 studies that investigate the factors (i.e., immersive qualities, contextual differences, and individual psychological traits) that predict social presence. Finally, the paper discusses the implications of heightened social presence and when it does and does not enhance one's experience in a virtual environment.

Agency and Gender Influence Older Adults' Presence-Related Experiences in an Interactive Virtual Environment

While virtual humans are increasingly used to benefit the elderly, considerably little is still known about older adults' virtual experiences. However, due to age-related changes, older adults' perceptions of virtual environments (VEs) may be unique. Hence, our objective was to examine possible gender differences in immersion, flow, and emotional states as well as physical and social presence in elderly males and females interacting either with a computer-controlled agent or a human-controlled avatar. Seventy-eight German-speaking older adults were randomly assigned to an avatar or an agent condition and were exposed to a brief social encounter in a virtual café. Results indicate no overall gender differences, but a significant effect of agency on social presence, physical presence, immersion, and flow. Participants in the avatar condition reported higher levels in all measures, except for involvement. Furthermore, significant gender × agency interactions were found, with females showing more social presence, spatial presence, and flow when interacting with a human-controlled avatar and more realism when conversing with an agent. Also, all participants showed significant changes in their affect post exposure. In sum, older adults' virtual experiences seem to follow unique patterns, yet, they do not preclude the elderly from successfully participating in VEs.

The influence of threat on perceived spatial distance to out-group members

A classic example of discriminatory behavior is keeping spatial distance from an out-group member. To explain this social behavior, the literature offers two alternative theoretical options that we label as the "threat hypothesis" and the "shared-experience hypothesis". The former relies on studies showing that out-group members create a sense of alertness. Consequently, potentially threatening out-group members are represented as spatially close allowing the prevention of costly errors. The latter hypothesis suggests that the observation of out-group members reduces the sharing of somatosensory experiences and, thus, increases the perceived physical distance between oneself and others. In the present paper, we pitted the two hypotheses against each other. In Experiment 1, Caucasian participants expressed multiple implicit "Near/Far" spatial categorization judgments from a Black-African Avatar and a White-Caucasian Avatar located in a 3D environment. Results indicate that the Black-African Avatar was categorized as closer to oneself, as compared with the White-Caucasian Avatar, providing support for "the threat hypothesis". In Experiment 2, we tested to which degree perceived threat contributes to this categorization bias by manipulating the avatar's perceived threat orthogonally to group membership. The results indicate that irrespective of group membership, threatening avatars were categorized as being closer to oneself as compared with no threatening avatars. This suggests that provided information about a person and not the mere group membership influences perceived distance to the person.

Loneliness predicts a preference for larger interpersonal distance within intimate space

Loneliness is thought to serve as an adaptive signal indicating the need to repair or replace salutary social connections. Accordingly, loneliness may influence preferences for interpersonal distance. If loneliness simply motivates a desire to socially reconnect, then loneliness may be associated with a preference for smaller interpersonal distances. According to the evolutionary model of loneliness, however, loneliness also signals an inadequacy of mutual aid and protection, augmenting self-preservation motives. If loneliness both increases the motivation to reconnect and increases the motivation for self-protection, then the resulting approach-avoidance conflict should produce a preference for larger interpersonal distance, at least within intimate (i.e., proximal) space. Here, we report two survey-based studies of participants’ preferences for interpersonal distance to distinguish between these competing hypotheses. In Study 1 (N = 175), loneliness predicted preferences for larger interpersonal distance within intimate space net gender, objective social isolation, anxiety, depressive symptomatology, and marital status. In Study 2 (N = 405), we replicated these results, and mediation analyses indicated that measures of social closeness could not adequately explain our findings. These studies provide compelling evidence that loneliness predicts preferences for larger interpersonal distance within intimate space, consistent with predictions from the evolutionary model of loneliness.

The Object Orientation Effect in Exocentric Distances

The object orientation effect describes shorter perceived distances to the front than to the back of oriented objects. The present work extends previous studies in showing that the object orientation effect occurs not only for egocentric distances between an observer and an object, but also for exocentric distances, that are between two oriented objects. Participants watched animated virtual humans (avatars) which were either facing each other or looking away, and afterward adjusted a bar to estimate the perceived length. In two experiments, participants judged avatars facing each other as closer than avatars facing away from each other. As the judged distance was between two objects and did not involve the observer, results rule out an explanation that observers perceive object fronts as closer to prepare for future interaction with them. The second experiment tested an explanation by predictive coding, this is the extrapolation of the current state of affairs to likely future states here that avatars move forward. We used avatars standing on bridges either connecting them or running orthogonal to the inter-avatar line thus preventing forward movement. This variation of walkability did not influence participants’ judgments. We conclude that if predictive coding was used by participants, they did not consider the whole scene layout for prediction, but concentrated on avatars. Another potential explanation of the effect assumes a general asymmetrical distribution of inter-person distances: people facing each other might typically be closer to each other than when facing away and that this asymmetry is reflected as a bias in perception.

Social Cues Alter Implicit Motor Learning in a Serial Reaction Time Task

Learning is a central ability for human development. Many skills we learn, such as language, are learned through observation or imitation in social contexts. Likewise, many skills are learned implicitly, that is, without an explicit intent to learn and without full awareness of the acquired knowledge. Here, we asked whether performance in a motor learning task is modulated by social vs. object cues of varying validity. To address this question, we asked participants to carry out a serial reaction time (SRT) task in which, on each trial, people have to respond as fast and as accurately as possible to the appearance of a stimulus at one of four possible locations. Unbeknownst to participants, the sequence of successive locations was sequentially structured, so that knowledge of the sequence facilitates anticipation of the next stimulus and hence faster motor responses. Crucially, each trial also contained a cue pointing to the next stimulus location. Participants could thus learn based on the cue, or on learning about the sequence of successive locations, or on a combination of both. Results show an interaction between cue type and cue validity for the motor responses: social cues (vs. object cues) led to faster responses in the low validity (LV) condition only. Concerning the extent to which learning was implicit, results show that in the cued blocks only, the highly valid social cue led to implicit learning. In the uncued blocks, participants showed no implicit learning in the highly valid social cue condition, but did in all other combinations of stimulus type and cueing validity. In conclusion, our results suggest that implicit learning is context-dependent and can be influenced by the cue type, e.g., social and object cues.

The relation between bystanders' behavioral reactivity to distress and later helping behavior during a violent conflict in virtual reality

The occurrence of helping behavior is thought to be automatically triggered by reflexive reactions and promoted by intuitive decisions. Here, we studied whether reflexive reactions to an emergency situation are associated with later helping behavior in a different situation, a violent conflict. First, 29 male supporters of F.C. Barcelona performed a cued-reaction time task with a low and high cognitive load manipulation, to tap into reflexive and reflective processes respectively, during the observation of an emergency. Next, participants entered a bar in Virtual Reality and had a conversation with a virtual fellow supporter. During this conversation, a virtual Real Madrid supporter entered and started an aggressive argument with the fellow supporter that escalated into a physical fight. Verbal and physical interventions of the participant served as measures of helping behavior. Results showed that faster responses to an emergency situation during low, but not during high cognitive load, were associated with more interventions during the violent conflict. However, a tendency to describe the decision to act during the violent conflict as intuitive and reflex-like was related to more interventions. Further analyses revealed that a disposition to experience sympathy, other-oriented feelings during distressful situations, was related to self-reported intuitive decision-making, a reduced distance to the perpetrator, and higher in the intervening participants. Taken together, these results shed new light on helping behavior and are consistent with the notion of a motivational system in which the act of helping is dependent on a complex interplay between intuitive, reflexive and deliberate, reflective processes.

Listening to a conversation with aggressive content expands the interpersonal space

The distance individuals maintain between themselves and others can be defined as ‘interpersonal space’. This distance can be modulated both by situational factors and individual characteristics. Here we investigated the influence that the interpretation of other people interaction, in which one is not directly involved, may have on a person’s interpersonal space. In the current study we measured, for the first time, whether the size of interpersonal space changes after listening to other people conversations with neutral or aggressive content. The results showed that the interpersonal space expands after listening to a conversation with aggressive content relative to a conversation with a neutral content. This finding suggests that participants tend to distance themselves from an aggressive confrontation even if they are not involved in it. These results are in line with the view of the interpersonal space as a safety zone surrounding one’s body.

Healthy young adults implement distinctive avoidance strategies while walking and circumventing virtual human vs. non-human obstacles in a virtual environment

This study examines how three types of obstacles (cylinder, virtual human and virtual human with footstep sounds) affect circumvention strategies of healthy young adults. Sixteen participants aged 25.2 ± 2.5 years (mean ± 1SD) were tested while walking overground and viewing a virtual room through a helmet mounted display. As participants walked towards a stationary target in the far space, they avoided an obstacle (cylinder or virtual human) approaching either from the right (+40°), left (-40°) or head-on (0°). Obstacle avoidance strategies were characterized using the position and orientation of the head. Repeated mixed model analysis showed smaller minimal distances (p = 0.007) while avoiding virtual humans as compared to cylinders. Footstep sounds added to virtual humans did not modify (p = 0.2) minimal distances compared to when no sound was provided. Onset times of avoidance strategies were similar across conditions (p = 0.06). Results indicate that the nature of the obstacle (human-like vs. non-human object) matters and can modify avoidance strategies. Smaller obstacle clearances in response to virtual humans may reflect the use of a less conservative avoidance strategy, due to a resemblance of obstacles to pedestrians and a recall of strategies used in daily locomotion. The lack of influence of footstep sounds supports the fact that obstacle avoidance primarily relies on visual cues and the principle of 'inverse effectiveness' whereby multisensory neurons' response to multimodal stimuli becomes weaker when the unimodal sensory stimulus (vision) is strong. Present findings should be taken into consideration to optimize the ecological validity of VR-based obstacle avoidance paradigms used in research and rehabilitation.

The effect of height and shoulder-to-hip ratio on interpersonal space in virtual environment

Previous research has associated men's physical features such as height and Shoulder-to-Hip Ratio (SHR) with dominance. Proxemics literature has suggested that the interpersonal space (comfort distance) increases in threatening and uncomfortable situations and decreases in unthreatening and comfortable situations. In the current study, we aimed to investigate the effect of different heights and SHRs on comfortable interpersonal distance by systematic manipulation of virtual confederates bodily features. More specifically, participants determined their comfort distances from virtual male confederates with different heights and SHRs in a virtual environment. We hypothesized that a virtual confederate's height and SHR influences the perception of interpersonal dominance; and consequently interpersonal space increases for taller and broader confederates as a result of increased interpersonal dominance. Results showed that comfortable interpersonal distance was positively associated with height for male participants, but not for female participants. No effect was found for shoulder width, neither for male nor female participants. Results were discussed in terms of the importance of height as a signal of dominance and fighting ability.

Model of Illusions and Virtual Reality

In Virtual Reality (VR) it is possible to induce illusions in which users report and behave as if they have entered into altered situations and identities. The effect can be robust enough for participants to respond “realistically,” meaning behaviors are altered as if subjects had been exposed to the scenarios in reality. The circumstances in which such VR illusions take place were first introduced in the 80's. Since then, rigorous empirical evidence has explored a wide set of illusory experiences in VR. Here, we compile this research and propose a neuroscientific model explaining the underlying perceptual and cognitive mechanisms that enable illusions in VR. Furthermore, we describe the minimum instrumentation requirements to support illusory experiences in VR, and discuss the importance and shortcomings of the generic model.

The Plausibility of a String Quartet Performance in Virtual Reality

We describe an experiment that explores the contribution of auditory and other features to the illusion of plausibility in a virtual environment that depicts the performance of a string quartet. 'Plausibility' refers to the component of presence that is the illusion that the perceived events in the virtual environment are really happening. The features studied were: Gaze (the musicians ignored the participant, the musicians sometimes looked towards and followed the participant's movements), Sound Spatialization (Mono, Stereo, Spatial), Auralization (no sound reflections, reflections corresponding to a room larger than the one perceived, reflections that exactly matched the virtual room), and Environment (no sound from outside of the room, birdsong and wind corresponding to the outside scene). We adopted the methodology based on color matching theory, where 20 participants were first able to assess their feeling of plausibility in the environment with each of the four features at their highest setting. Then five times participants started from a low setting on all features and were able to make transitions from one system configuration to another until they matched their original feeling of plausibility. From these transitions a Markov transition matrix was constructed, and also probabilities of a match conditional on feature configuration. The results show that Environment and Gaze were individually the most important factors influencing the level of plausibility. The highest probability transitions were to improve Environment and Gaze, and then Auralization and Spatialization. We present this work as both a contribution to the methodology of assessing presence without questionnaires, and showing how various aspects of a musical performance can influence plausibility.

Identifying Anxiety Through Tracked Head Movements in a Virtual Classroom

Virtual reality allows the controlled simulation of complex social settings, such as classrooms, and thus provides an opportunity to test a range of theories in the social sciences in a way that is both naturalistic and controlled. Importantly, virtual environments also allow the body movements of participants in the virtual world to be tracked and recorded. In the following article, we discuss how tracked head movements were correlated with participants' reports of anxiety in a simulation of a classroom. Participants who reported a high sense of awareness of and concern about the other virtual people in the room showed different patterns of head movement (more lateral head movement, indicating scanning behavior) from those who reported a low level of concern. We discuss the implications of this research for understanding nonverbal behavior associated with anxiety and for the design of online educational systems.

Mapping Social Interactions: The Science of Proxemics

Interpersonal distance and gaze provide a wealth of information during face-to-face social interactions. These "proxemic" behaviors offer a window into everyday social cognition by revealing interactants' affective states (e.g., interpersonal attitudes) and cognitive responses (e.g., social attention). Here we provide a brief overview of the social psychological literature in this domain. We focus on new techniques for experimentally manipulating and measuring proxemics, including the use of immersive virtual environments and digital motion capture. We also discuss ways in which these approaches can be integrated with psychophysiological and neuroimaging techniques. Throughout, we argue that contemporary proxemics research provides psychology and neuroscience with a means to study social cognition and behavior as they naturally emerge and unfold in vivo.

Parkinson Patients' Initial Trust in Avatars: Theory and Evidence

Parkinson's disease (PD) is a neurodegenerative disease that affects the motor system and cognitive and behavioral functions. Due to these impairments, PD patients also have problems in using the computer. However, using computers and the Internet could help these patients to overcome social isolation and enhance information search. Specifically, avatars (defined as virtual representations of humans) are increasingly used in online environments to enhance human-computer interaction by simulating face-to-face interaction. Our laboratory experiment investigated how PD patients behave in a trust game played with human and avatar counterparts, and we compared this behavior to the behavior of age, income, education and gender matched healthy controls. The results of our study show that PD patients trust avatar faces significantly more than human faces. Moreover, there was no significant difference between initial trust of PD patients and healthy controls in avatar faces, while PD patients trusted human faces significantly less than healthy controls. Our data suggests that PD patients' interaction with avatars may constitute an effective way of communication in situations in which trust is required (e.g., a physician recommends intake of medication). We discuss the implications of these results for several areas of human-computer interaction and neurological research.