Commodity-level virtual reality equipment is now available to all ages. To better understand how cognitive development affects people’s spatial memory in virtual reality, we assess how adults (20-29 years old) and teenagers (14-17 years old) represent their spatial memory of objects in an immersive virtual environment (IVE) where height is encoded. Despite virtual reality being a favorable conduit for the study of egocentric spatial memory, prior studies have predominately looked at objects placed at similar heights. Within a stairwell environment, participants learned the positions of nine target objects. In one condition, all objects were placed near eye height. In another, they were placed at varying heights. Our results indicate that participants’ errors and latencies were similar in both environments, and across age groups. Our results have implications for the development of IVEs and the expansion of immersive technology to a more diverse, younger audience.

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.

As virtual reality expands in popularity, an increasingly diverse audience is gaining exposure to immersive virtual environments (IVEs). A significant body of research has demonstrated how perception and action work in such environments, but most of this work has been done studying adults. Less is known about how physical and cognitive development affect perception and action in IVEs, particularly as applied to preteen and teenage children. Accordingly, in the current study we assess how preteens (children aged 8-12 years) and teenagers (children aged 15-18 years) respond to mismatches between their motor behavior and the visual information presented by an IVE. Over two experiments, we evaluate how these individuals recalibrate their actions across functionally distinct systems of movement. The first experiment analyzed forward walking recalibration after exposure to an IVE with either increased or decreased visual flow. Visual flow during normal bipedal locomotion was manipulated to be either twice or half as fast as the physical gait. The second experiment leveraged a prism throwing adaptation paradigm to test the effect of recalibration on throwing movement. In the first experiment, our results show no differences across age groups, although subjects generally experienced a post-exposure effect of shortened distance estimation after experiencing visually faster flow and longer distance estimation after experiencing visually slower flow. In the second experiment, subjects generally showed the typical prism adaptation behavior of a throwing after-effect error. The error lasted longer for preteens than older children. Our results have implications for the design of virtual systems with children as a target audience.

Interesting virtual environments that permit free exploration are rarely small. A number of techniques have been developed to allow people to walk in larger virtual spaces than permitted by physical extent of the virtual reality hardware, and in this paper we compare three such methods in terms of how they affect presence and spatial awareness. In our first psychophysical study, we compared two methods of reorientation and one method of redirected walking on subjects' presence and spatial memory while navigating a pre-specified path. We further compared the two reorientation methods in a second psychophysical study involving free exploration and navigation in a large virtual environment. Our results provide criteria by which the choice of a locomotion method for navigating large virtual environments may be selected.

Vection is the illusion of self-motion, usually induced by a visual stimulus. It is important in virtual reality because inducing it in motion simulations can lead to improved experiences. We examine linear and circular vection in commodity level head-mounted displays. We compare the experience of circular vection induced through a real world stimulus, an optokinetic drum, with that experienced through a virtual stimulus. With virtual stimuli, we also compare circular vection with linear horizontal and linear vertical vection. Finally, we examine circular and linear vection in more naturalistic virtual environments. Linear vection was induced more rapidly than any other type, but circular vection occurs more rapidly with a real world stimulus than a virtual one. Our results have practical application and can inform virtual reality design that uses head-mounted display technology and wishes to establish vection. Circular vection can be induced easily and rapidly through visual mechanisms that have been known since Mach [1]. We have an optokinetic drum that is capable of inducing compelling circular vection that works in almost all people we have tested in it. The goal of this project is thus twofold: (1) to see how well and how reliably vection can be induced in virtual reality with commodity-level HMDs as compared to real-world stimuli, and (2) to see if compelling vection could be comparably induced when the stimuli are complex naturalistic scenes, not abstract optic flow patterns.

Collaborative immersive virtual environments allow the behavior of one user to be observed by other users. In particular, behavior of users in such an environment is represented by each user possessing a self-avatar, a digital representation of themself. In this study we examined dyadic interactions in a collaborative immersive virtual environment when both users were present in the same physical space. This collocation in physical space allows for physical interaction between users as well as virtual interaction. In the context of a common physical gesture, high fiving, we examined the question of whether the form of the self-avatar was important, and whether collocation in the physical world provided benefits or not. We find that the form of the avatar is important but that physical collocation is not. These results reinforce the growing body of evidence that indicates that having a full-body avatar in a virtual environment provides benefits, and these results are significant because they demonstrate this in the context of a dyadic interaction.

People judge what they can and cannot do all the time when acting in the physical world. Can I step over that fence or do I need to duck under it? Can I step off of that ledge or do I need to climb off of it? These qualities of the environment that people perceive that allow them to act are called affordances. This article compares people’s judgments of affordances on two tasks in both the real world and in virtual environments presented with head-mounted displays. The two tasks were stepping over or ducking under a pole, and stepping straight off of a ledge. Comparisons between the real world and virtual environments are important because they allow us to evaluate the fidelity of virtual environments. Another reason is that virtual environment technologies enable precise control of the myriad perceptual cues at work in the physical world and deepen our understanding of how people use vision to decide how to act. In the experiments presented here, the presence or absence of a self-avatar—an animated graphical representation of a person embedded in the virtual environment—was a central factor. Another important factor was the presence or absence of action, that is, whether people performed the task or reported that they could or could not perform the task. The results show that animated self-avatars provide critical information for people deciding what they can and cannot do in virtual environments, and that action is significant in people’s affordance judgments.

We explore whether a gender-matched, calibrated self-avatar affects the perception of the affordance of stepping off of a ledge, or visual cliff, in an immersive virtual environment. Visual cliffs form demonstrations in many immersive virtual environments because they create compelling environments. Understanding the role that self-avatars contribute to making such environments compelling is an important problem. We conducted an experiment to find the threshold at which subjects on a ledge in an immersive virtual environment would report that they could step gracefully off of the ledge without losing their balance, and compared the threshold height at which their decision changed under the condition of having and not having a self-avatar. The results show that people unrealistically say they can step off a ledge that is approximately 50% of their eyeheight without a self-avatar, and realistically about 25% of their eyeheight with a self-avatar.

In this study, we examine subjects' spatial orientation in a head--mounted display (HMD) based virtual environment (VE) when objects are placed at different vertical viewing angles. More specifically, we examine spatial orientation when subjects memorize the location of objects on the ground, at eyelevel, and up in the air. Interestingly, we found that spatial orientation was the same across all conditions. This finding is important because it informs researchers who use similar spatial orientation tasks that variations in viewing neck angle to targets is not necessarily an issue.

The purpose of this study was to learn if self-avatars influence people's perception and action in virtual environments. People viewed two situations in a virtual environment through a head-mounted display and were asked to decide how they would act. In one situation their task was to imagine walking across a room which was divided by a horizontal bar. The bar's height was varied and the task was for people to say whether they would need to step over the bar or duck under it. In the other situation the task was to imagine walking through a doorway. The doorway's height was varied and the task was for people to say whether they could walk straight through the doorway or would need to duck to pass through. One-half the participants viewed the situations with a self-avatar and the others viewed it without an avatar. The height of the avatar was varied, so that it either equaled the participant's height or it was 15% taller. The results showed statistically significant effects of the avatar in the horizontal bar situation: their step-over or duck-under decision points were about 12% higher when the self-avatar was rendered taller. In the doorway situation the effect of the avatar was statistically non-significant. The step-over step-under task is a promising method to study perception and action in virtual environments.

When we locomote through real or virtual environments, self-to-object relationships constantly change. Nevertheless, in real environments we effortlessly maintain an ongoing awareness of roughly where we are with respect to our immediate surrounds, even in the absence of any direct perceptual support (e.g., in darkness or with eyes closed). In virtual environments, however, we tend to get lost far more easily. Why is that? Research suggests that physical motion cues are critical in facilitating this “automatic spatial updating” of the self-to-surround relationships during perspective changes. However, allowing for full physical motion in VR is costly and often unfeasible. Here, we demonstrated for the first time that the mere illusion of self-motion (“circular vection”) can provide a similar benefit as actual self-motion: While blindfolded, participants were asked to imagine facing new perspectives in a well-learned room, and point to previously-learned objects. As expected, this task was difficult when participants could not physically rotate to the instructed perspective. Performance was significantly improved, however, when they perceived illusory self-rotation to the novel perspective (even though they did not physically move). This circular vection was induced by a combination of rotating sound fields (“auditory vection”) and biomechanical vection from stepping along a carrousel-like rotating floor platter. In summary, illusory self-motion was shown to indeed facilitate perspective switches and thus spatial orientation. These findings have important implications for both our understanding of human spatial cognition and the design of more effective yet affordable VR simulators. In fact, it might ultimately enable us to relax the need for physical motion in VR by intelligently utilizing self-motion illusions.

The use of vection, the illusion of self-movement, has recently been explored as a novel way to immerse observers in mediated environments through illusory yet compelling self-motion without physically moving. This provides advantages over existing systems that employ costly, cumbersome, and potentially hazardous motion platforms, which are often surprisingly inadequate to provide life-like motion experiences. This study investigates whether spatialized sound rotating around the stationary, blindfolded listener can facilitate biomechanical vection, the illusion of self-rotation induced by stepping along a rotating floor plate. For the first time, integrating simple auditory and biomechanical cues for turning in place evoked convincing circular vection. In an auditory baseline condition, participants experienced only spatialized auditory cues. In a purely biomechanical condition, seated participants stepped along sideways on a rotating plate while listening to mono masking sounds. Scores of the bi-modal condition (binaural+biomechanical cues) exceeded the sum of both single cue conditions, which may imply super-additive or synergistic effects.

Sound fields rotating around stationary blindfolded listeners sometimes elicit auditory circular vection, the illusion that the listener is physically rotating. Experiment 1 investigated whether auditory circular vection depends on participants' situational awareness of “movability,” that is, whether they sense/know that actual motion is possible or not. While previous studies often seated participants on movable chairs to suspend the disbelief of self-motion, it has never been investigated whether this does, in fact, facilitate auditory vection. To this end, 23 blindfolded participants were seated on a hammock chair with their feet either on solid ground (“movement impossible”) or suspended (“movement possible”) while listening to individualized binaural recordings of two sound sources rotating synchronously at 60°/s. Although participants never physically moved, situational awareness of movability facilitated auditory vection. Moreover, adding slight vibrations like the ones resulting from actual chair rotation increased the frequency and intensity of vection. Experiment 2 extended these findings and showed that nonindividualized binaural recordings were as effective in inducing auditory circular vection as individualized recordings. These results have important implications both for our theoretical understanding of self-motion perception and for the applied field of self-motion simulations, where vibrations, nonindividualized binaural sound, and the cognitive/perceptual framework of movability can typically be provided at minimal cost and effort.

This paper describes the use of a treadmill-based virtual environment (VE) to investigate the influence of visual motion on locomotion. First, we establish that a computer-controlled treadmill coupled with a wide field of view computer graphics display can be used to study interactions between perception and action. Previous work has demonstrated that humans recalibrate their visually directed actions to changing circumstances in their environment. Using a treadmill VE, we show that recalibration of action is reflected in the real world as a result of manipulating the relation between the visual indication of speed, presented using computer graphics, and the biomechanical speed of walking on a treadmill. We then extend this methodology to investigate whether the recalibration is based on perception of the speed of movement through the world or on the magnitude of optic flow itself. This was done by utilizing two different visual displays, which had essentially the same magnitude of optic flow, but which differed in the information present for the speed of forward motion. These results indicate that changes in optic flow are not necessary for recalibration to occur. The recalibration effect is dependent, at least in part, on visual perception of the speed of self-movement.

This paper presents results that demonstrate functional similarities in subjects' access to spatial knowledge (or spatial representation ) between real and virtual environments. Such representations are important components of the transfer of reasoning ability and knowledge between these two environments. In particular, we present two experiments aimed at investigating similarities in spatial knowledge derived from exploring on foot both physical environments and virtual environments presented through a head-mounted display. In the first experiment, subjects were asked to learn the locations of target objects in the real or virtual environment and then rotate the perspective by either physically locomoting to a new facing direction or imagining moving. The latencies and errors were generally worse after imagining locomoting and for greater degrees of rotation in perspective; they did not differ significantly across knowledge derived from exploring the physical versus virtual environments. In the second experiment, subjects were asked to imagine simple rotations versus simple translations in perspective. The errors and latencies indicated that the to-be-imagined disparity was linearly related after learning the physical and virtual environment. These results demonstrate functional similarities in access to knowledge of new perspective when it is learned by exploring physical environments and virtual renderings of the same environment.

Distance judgments are difficult in current virtual environments, limiting their effectiveness in conveying spatial information. This problem is apparent when contact occurs while a user is manipulating objects. In particular, the computer graphics used to support current-generation immersive interfaces does a poor job of providing the visual cues necessary to perceive when contact between objects is about to occur. This perception of imminent contact is important in human motor control. Its absence prevents a sense of naturalness in interactive displays which allow for object manipulation. This paper reports results from an experiment evaluating the effectiveness of binocular disparity, cast shadows and diffuse inter-reflections in signaling imminent contact in a manipulation task.