Measurement of presence and its consequences in virtual environments

A sense of presence is one of the critical components required by any effective virtual environment (VE). In contrast, side effects such as sickness may be produced in some virtual environments, detracting from the enjoyment or usefulness of the VE and from subsequent performance of the participant. Both presence and sickness in virtual environments are multifactorial phenomena not easily amenable to understanding or measurement. The first experiment reported here compares use of direct performance measures and rating scales to assess presence, whilst varying the VE display medium (head mounted and desktop displays) and whether or not sound was used in the VE. The second experiment addresses associations between presence, sickness and enjoyment of virtual environment participation. There was enough comparability between a reflex response within the VE and the rating scales to justify future exploration of the former measure of presence. A number of explanations are given for the partial association found between presence and sickness.     

Effects of virtual presence and learning outcome using low-end virtual reality systems

Low-cost technology is essential to integrate Virtual Reality (VR) into educative institutions around the world. However, low-cost technology usually refers to low-end technology, which may compromise the level of immersion of the VR system. This study evaluates whether low-end and high-end VR systems achieve a comparable learning outcome regardless their immersion level. We also analyze the relationship between virtual presence and the learning outcome arising from a VR educational experience. An evaluation with 42 participants was conducted. We measured learning outcome and virtual presence under three different configurations, namely: a desktop computer, a low-end VR system, and a high-end VR system. The impact of simulator sickness was also analyzed. Results revealed a lower learning outcome in the less immersive configuration (i.e. desktop) and a similar learning outcome in both low-end and high-end VR systems. Even though low-end VR systems are less immersive and produce a lower level of virtual presence than high-end VR systems, the results support the use of low-end VR systems for educative applications.     

Cognitive and affective processes for learning science in immersive virtual reality

As immersive virtual reality (IVR) systems proliferate in classrooms, it is important to understand how they affect learning outcomes and the underlying affective and cognitive processes that may cause these outcomes. Proponents argue that IVR could improve learning by increasing positive affective and cognitive processing, thereby supporting improved performance on tests of learning outcome, whereas opponents of IVR contend that it could hurt learning by increasing distraction, thereby disrupting cognitive learning processes and leading to poorer learning outcomes. In a media comparison study, students viewed a biology lesson either as an interactive animated journey in IVR or as a slideshow on a desktop monitor. Those who viewed the IVR lesson performed significantly worse on transfer tests, reported higher emotional arousal, reported more extraneous cognitive load and showed less engagement based on EEG measures than those who viewed the slideshow lesson, with or without practice questions added to the lessons. Mediational analyses showed that the lower retention scores for the IVR lesson were related to an increase in self-reported extraneous cognitive load and emotional arousal. These results support the notion that immersive environments create high affective and cognitive distraction, which leads to poorer learning outcomes than desktop environments.     

A comparative study of mobile map displays in a geographic orientation task

In an ergonomic experiment, different mobile map displays were compared in a simulated geographical orientation task. Subjects had to cross mazes while the corresponding maps were presented on a hand-held display, two helmet-mounted displays (a retinal scanning and a liquid crystal display) or on paper. The simulated mazes were projected on a backlit screen and the subjects could cross them using a joystick. The displays were compared with regard to subjects' speed when crossing the mazes, experienced task difficulty, visual fatigue and simulator sickness. The results show that speed was lowest with the paper map and experienced task difficulty was highest, whereas no significant differences were found between the electronic displays. Visual fatigue and simulator sickness were low and no significant differences were observed between all displays. The conclusion is drawn that all electronic map displays can be used for short time periods (15 - 30 minutes); however, long term effects have to be analysed in future experimental studies.     

A comparative study of mobile map displays in a geographic orientation task

In an ergonomic experiment, different mobile map displays were compared in a simulated geographical orientation task. Subjects had to cross mazes while the corresponding maps were presented on a hand-held display, two helmet-mounted displays (a retinal scanning and a liquid crystal display) or on paper. The simulated mazes were projected on a backlit screen and the subjects could cross them using a joystick. The displays were compared with regard to subjects' speed when crossing the mazes, experienced task difficulty, visual fatigue and simulator sickness. The results show that speed was lowest with the paper map and experienced task difficulty was highest, whereas no significant differences were found between the electronic displays. Visual fatigue and simulator sickness were low and no significant differences were observed between all displays. The conclusion is drawn that all electronic map displays can be used for short time periods (15 – 30 minutes); however, long term effects have to be analysed in future experimental studies.     

Design issues encountered in the development of a mobile multimedia augmentative communication service

Augmentative and alternative communication (AAC) systems can be mounted on a range of different hardware platforms, from custom-designed units to desktop or laptop personal computers and hand-held and palmtop systems. Palmtop devices such as personal data assistants (PDAs) offer great advantages of portability. The small display size and limited storage and processing capacity of a PDA compared to larger systems are likely to impose some limitations on the range of AAC applications which can be supported, however, particularly when multimedia-based applications are considered. This paper addresses issues involved in migrating a multimedia AAC application onto a palm-top PDA and discusses the user involvement in the re-engineering of the system for that environment. Outcomes from an initial practical trial with a person who uses AAC are reported.     

The effects of simulated fog and motion on simulator sickness in a driving simulator and the duration of after-effects

In the study, we checked: 1) how the simulator test conditions affect the severity of simulator sickness symptoms; 2) how the severity of simulator sickness symptoms changes over time; and 3) whether the conditions of the simulator test affect the severity of these symptoms in different ways, depending on the time that has elapsed since the performance of the task in the simulator.     

System design and user evaluation of Co-Star: An immersive stereoscopic system for cable harness design

The system design and results of a user evaluation of Co-Star an immersive design system for cable harness design is described. The system used a stereoscopic head mounted graphical display, user motion tracking and hand-gesture controlled interface to enable cable harnesses to be designed using direct 3D user interaction with a product model. In order to determine how such a system interface would be used by a designer and to obtain user feedback on its main features a practical user evaluation was undertaken involving ten participants each completing three cable harness design tasks with the system. All user interactions with the system were recorded in a time stamped log file during each of the tasks, which were also followed by questionnaire (5 point scale) and interview sessions with each participant. The recorded interaction data for the third task was analysed using functional decomposition techniques and used to construct a single activity profile for the task based on the mean results obtained from the participant group. The goal was to identify in general terms the relative distribution of user activity between specific purposes during practical system operation, and it was found that in this task Navigation accounted for 41%, Design 27%, System Operation 23% and looking at Task Instructions 9% of all user activity. The scored questionnaire data collected immediately after the completion of each task was used to rank the major features of the system according to user opinion. This was further enhanced by also collecting real interview comments from the user group about these same features. The combination of both quantitative performance analysis and subjective user opinion data obtained during a practical design exercise has enabled an in depth evaluation of the system, leading to a much greater understanding of many of the key user and interface requirements that should be considered during the development of immersive interfaces and systems for practical engineering applications.     

Interaction with an immersive virtual environment corrects users' distance estimates

OBJECTIVE: Two experiments examined whether prior interaction within an immersive virtual environment (VE) enabled people to improve the accuracy of their distance judgments and whether an improved ability to estimate distance generalized to other means of estimating distances. BACKGROUND: Prior literature has consistently found that users of immersive VEs underestimate distances by approximately 50%. METHOD: In each of the two experiments, 16 participants viewed objects in an immersive VE and estimated their distance to them by means of blindfolded walking tasks before and after interacting with the VE. RESULTS: The interaction task significantly corrected users' underestimation bias to nearly veridical. Differences between pre- and post-interaction mean distance estimation accuracy were large (d = 4.63), and significant (p < .001), and they generalized across response task. CONCLUSION: This finding limits the generality of the underestimation effect in VEs and suggests that distance underestimation in VEs may not be a road block to the development of VE applications. APPLICATION: Potential or actual applications of this research include the improvement of VE systems requiring accurate spatial awareness.     

Design and display of enhancing information in desktop information-rich virtual environments: challenges and techniques

Information-rich virtual environments (IRVEs) have been described as environments in which perceptual information is enhanced with abstract (or symbolic) information, such as text, numbers, images, audio, video, or hyperlinked resources. Desktop virtual environment (VE) applications present similar information design and layout challenges as immersive VEs, but, in addition, they may also be integrated with external windows or frames commonly used in desktop interfaces. This paper enumerates design approaches for the display of enhancing information both internal and external to the virtual worlds render volume. Using standard Web-based software frameworks, we explore a number of implicit and explicit spatial layout methods for the display and linking of abstract information, especially text. Within the VE view, we demonstrate both heads-up-displays (HUDs) and encapsulated scenegraph behaviors we call semantic objects. For desktop displays, which support information display venues external to the scene, we demonstrate the linking and integration of the scene with Web browsers and external visualization applications. Finally, we describe the application of these techniques in the PathSim visualizer, an IRVE interface for the biomedical domain. These design techniques are relevant to instructional and informative interfaces for a wide variety of VE applications.     

Assessing the influence of repeated exposures and mental stress on human wayfinding performance in indoor environments using virtual reality technology

This study aimed to examine the effect of repeated exposures to indoor environments on people’s indoor wayfinding performance, both under normal condition and during fire emergency which could induce significant mental stress. Indoor wayfinding experiments were conducted in an immersive virtual museum developed using virtual reality technologies. Participants of the experiments were divided into three groups, who participated in one, two and three trials, respectively. Those who participated in more than one trial were given an interval of two weeks between two consecutive trials. Each trial of the experiment included a treasure hunting task and an egress task. Participants were presented with a virtual fire emergency during the egress task of their last trial. Data of wayfinding performance measures of the participants, as well as their physiological and emotional responses, sense of direction, wayfinding anxiety and simulator sickness were collected and analyzed. The results revealed significant positive impact of repeated exposure on participants’ wayfinding performance, which resulted in a decrease in the time needed to complete the treasure hunting task. The results also revealed significant negative impact of mental stressed caused by the fire emergency on participants’ wayfinding performance, which led to increased travel time and distance during egress. Such negative impact of stress, however, could be noticeably diminished by the repeated exposures, showing significant interaction effect between these two factors.     

Task performance in a head-mounted display: The impacts of varying latency

The purpose of this study was to determine how latency in a head-mounted display (HMD) affects human performance. Virtual environments (VEs) are used frequently for training. However, VEs can cause simulator sickness. Prior work in our laboratory has examined the role of varying latency in simulator sickness. However, the effect of varying latency on task performance has not been examined. Subjects participated in a repeated measures study where they were exposed to two different latency conditions in an HMD: constant (70 ms) and varying (70–270 ms). During each HMD exposure, subjects used a laser pointer to repeatedly “shoot” at laser targets while accuracy and time-to-hit were recorded. Subjects scored fewer hits and took longer to hit targets in the varying latency condition. These findings indicate that individuals exposed to varying latency perform worse than individuals exposed to a lower constant latency.     

A neuro-fuzzy warning system for combating cybersickness in the elderly caused by the virtual environment on a TFT-LCD

Only a few studies in the literature have focused on the effects of age on virtual environment (VE) sickness susceptibility and even less research was carried out focusing on the elderly. In general, the elderly usually browse VEs on a thin film transistor liquid crystal display (TFT-LCD) at home or somewhere, not a head-mounted display (HMD). While the TFT-LCD is used to present VEs, this set-up does not physically enclose the user. Therefore, this study investigated the factors that contribute to cybersickness among the elderly when immersed into a VE on TFT-LCD, including exposure durations, navigation rotating speeds and angle of inclination. Participants were elderly, with an average age of 69.5 years. The results of the first experiment showed that the rate of simulator sickness questionnaire (SSQ) scores increases significantly with navigational rotating speed and duration of exposure. However, the experimental data also showed that the rate of SSQ scores does not increase with the increase in angle of inclination. In applying these findings, the neuro-fuzzy technology was used to develop a neuro-fuzzy cybersickness-warning system integrating fuzzy logic reasoning and neural network learning. The contributing factors were navigational rotating speed and duration of exposure. The results of the second experiment showed that the proposed system can efficiently determine the level of cybersickness based on the associated subjective sickness estimates and combat cybersickness due to long exposure to a VE.     

Video game experience predicts virtual, but not real navigation performance

In recent years, studies have shown that video game experience is related to improvements across a variety of cognitive and visuospatial tasks. This study investigated the relationship between prior video game experience and spatial performance in virtual and real environments. Across two experiments, gaming experience was related to performance in desktop virtual environments; those with more video game experience were more accurate in pointing to nonvisible targets. In contrast, gaming experience was unrelated to three different real environment tasks, suggesting that video games may primarily influence perceptual and cognitive abilities in the visual domain over abilities that also involve kinesthetic or vestibular input. Contrary to expectations, gaming experience was also related to performance in immersive virtual environments, which may be related to the use of a joystick interface during immersive travel. Video game experience was also positively related to performance in a dynamic spatial task and to verbal SAT and math SAT scores. Sex differences in desktop virtual navigation and dynamic spatial ability were eliminated when game experience was included as a covariate.     

Vision‐tangible interactive display method for mixed and virtual reality: Toward the human‐centered editable reality

Building a human‐centered editable world can be fully realized in a virtual environment. Both mixed reality (MR) and virtual reality (VR) are feasible solutions to support the attribute of edition. Based on the current development of MR and VR, we present the vision‐tangible interactive display method and its implementation in both MR and VR. We address the issue of MR and VR together because they are similar regarding the proposed method. The editable mixed and virtual reality system is useful for studies, which exploit it as a platform. In this paper, we construct a virtual reality environment based on the Oculus Rift, and an MR system based on a binocular optical see‐through head‐mounted display. In the MR system about manipulating the Rubik's cube, and the VR system about deforming the virtual objects, the proposed vision‐tangible interactive display method is utilized to provide users with a more immersive environment. Experimental results indicate that the vision‐tangible interactive display method can improve the user experience and can be a promising way to make the virtual environment better.     

The effect of 3–25 Hz vibration on the legibility of numeric light emitting diode displays

This paper describes the effects of 3 – 25 Hz sinusoidal vibration applied in both the vertical and lateral axes on the performance of a reading task. The task was to read aloud numeric characters presented on a yellow high luminance light emitting diode display. The subjects were strapped into an ejection seat which was mounted on the same vibration platform as the display. Tests were conducted with the subject's head held both against and just off the head rest. The results indicate that reading performance was affected most by lateral vibration, when the head was against the rest.     

An evaluation of immersive viewing on spatial knowledge acquisition in spherical panoramic environments

We report the results of an experiment conducted to examine the effects of immersive viewing on a common spatial knowledge acquisition task of spatial updating task in a spherical panoramic environment (SPE). A spherical panoramic environment, such as Google Street View, is an environment that is comprised of spherical images captured at regular intervals in a real world setting augmented with virtual navigational aids such as paths, dynamic maps, and textual annotations. Participants navigated the National Mall area of Washington, DC, in Google Street View in one of two viewing conditions; desktop monitor or a head-mounted display with a head orientation tracker. In an exploration phase, participants were first asked to navigate and observe landmarks on a pre-specified path. Then, in a testing phase, participants were asked to travel the same path and to rotate their view in order to look in the direction of the perceived landmarks at certain waypoints. The angular difference between participants’ gaze directions and the landmark directions was recorded. We found no significant difference between the immersive and desktop viewing conditions on participants’ accuracy of direction to landmarks as well as no difference in their sense of presence scores. However, based on responses to a post-experiment questionnaire, participants in both conditions tended to use a cognitive or procedural technique to inform direction to landmarks. Taken together, these findings suggest that in both conditions where participants experience travel based on teleportation between waypoints, the visual cues available in the SPE, such as street signs, buildings and trees, seem to have a stronger influence in determining the directions to landmarks than the egocentric cues such as first-person perspective and natural head-coupled motion experienced in the immersive viewing condition.     

Psychophysiological evaluation of simulator sickness evoked by a graphic simulator

The present study investigated the effects of simulator sickness, as an important bias factor on evaluation of emotional changes under the controlled condition of driving a car for 60 min at a constant speed (60 km/h) in a graphic simulator. Simulator sickness was measured and analyzed every 5 min using both subjective evaluation and physiological signals. Results of the subjective evaluation showed there was a significant difference between the rest and the driving conditions 10 min after the main experiment started and that the level of difference increased linearly with time. Analysis of the central and the autonomic nervous systems showed the significant differences in delta, theta, alpha and beta bands of an electroencephalogram (EEG), skin temperature, and the R-R interval between the rest and the driving conditions after about 5 min from the start of driving. In particular, there was the highest correlation between parameter of theta and subjective evaluation, and thus theta was considered an effective physiological parameter for numerically evaluating simulator sickness. The results indicate that physiological changes due to simulator sickness can be a bias factor in evaluation of human sensibility.     

Head motion anticipation for virtual-environment applications using kinematics and EMG energy

Real-time human-computer interaction plays an important role in virtual-environment (VE) applications. Such interaction can be improved by detecting and reacting to the user's head motion. Today's VE systems use head-mounted inertial sensors to update and spatially stabilize the image displayed to a user through a head-mounted display. Since motion can only be detected after it has already occurred, latencies in the stabilization scheme can only be reduced but never eliminated. Such latencies slow down manual control, cause inaccuracies in matching real and virtual objects through a half-transparent display, and reduce the sense of presence. This paper presents novel methods for reducing VE latencies by anticipating future head motion based on electromyographic (EMG) signals originating from the major neck muscles and head kinematics; it also reports results for anticipation of 17.5 and 35 ms. Features extracted from the EMG signals are used to train a neural network in mapping EMG data, given present head kinematics, into future head motion. The trained network is then used in real time for head-motion anticipation, which gives the VE system the time advantage necessary to compensate for the inherent latencies. The main contribution of this work is the use of EMG energy and bounded head acceleration as the key input/output information, which results in improved performance compared to the previous work.