2,737 research outputs found

    Change blindness: eradication of gestalt strategies

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    Arrays of eight, texture-defined rectangles were used as stimuli in a one-shot change blindness (CB) task where there was a 50% chance that one rectangle would change orientation between two successive presentations separated by an interval. CB was eliminated by cueing the target rectangle in the first stimulus, reduced by cueing in the interval and unaffected by cueing in the second presentation. This supports the idea that a representation was formed that persisted through the interval before being 'overwritten' by the second presentation (Landman et al, 2003 Vision Research 43149–164]. Another possibility is that participants used some kind of grouping or Gestalt strategy. To test this we changed the spatial position of the rectangles in the second presentation by shifting them along imaginary spokes (by ±1 degree) emanating from the central fixation point. There was no significant difference seen in performance between this and the standard task [F(1,4)=2.565, p=0.185]. This may suggest two things: (i) Gestalt grouping is not used as a strategy in these tasks, and (ii) it gives further weight to the argument that objects may be stored and retrieved from a pre-attentional store during this task

    Evaluating immersive and non-immersive VR for spatial understanding in undergraduate construction education

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    In this paper we explore a pedagogical value of using immersive vir-tual reality to teach construction students how to identify and evaluate the spa-tial characteristics of their design in terms of sizes, layout or structural issues. This study builds on the premise that virtual reality, though generally valuable for design understanding, cannot be treated as a monolithic system when it comes to evaluating its effectiveness for tasks that differ in their objectives. The study extends the work of similar studies that have looked into the claimed ben-efits of immersion, stereoscopy or interactivity on visual perception and spatial cognition. We compared a desktop-based environment with a fully immersive virtual reality in the form of a wearable VR headset to see if there are any no-ticeable differences in how students review and evaluate spaces. Thirty-two par-ticipants from the first year undergraduate construction program were tasked to walk through a small residential house that incorporated up to 12 intentional de-sign mistakes in terms of the size, layout, position or structural oversight. Initial results suggest that the students using the HMD-type of VR slightly better per-form compared to those using the monitor. However, observations of students’ interactions with the model while completing the tasks suggest a greater com-plexity in how the navigation patterns, domain knowledge and technology expe-rience may be affecting the way they perceive the design

    Engineering data compendium. Human perception and performance. User's guide

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    The concept underlying the Engineering Data Compendium was the product of a research and development program (Integrated Perceptual Information for Designers project) aimed at facilitating the application of basic research findings in human performance to the design and military crew systems. The principal objective was to develop a workable strategy for: (1) identifying and distilling information of potential value to system design from the existing research literature, and (2) presenting this technical information in a way that would aid its accessibility, interpretability, and applicability by systems designers. The present four volumes of the Engineering Data Compendium represent the first implementation of this strategy. This is the first volume, the User's Guide, containing a description of the program and instructions for its use

    Factors Affecting Spatial Awareness in Non- Stereo Visual Representations of Virtual, Real and Digital Image Environments

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    The increasing number of applications employing virtual environment (VE) technologies as a tool, particularly those that use VE as surrogates, makes it important to examine the ability of VE to provide realistic simulations to users. Accurate space and distance perceptions have been suggested as essential preconditions for the reliable use of VE technologies in various applications. However, space and distance perception in the VE has been reported by some investigators as being perceived differently from the real world. Thus, the overall aim of this thesis is to improve our understanding of factors affecting spatial awareness in the VE. The general approach is based on a strategy of conducting empirical investigations comparing tasks performed in the VE to similar tasks performed in the real world. This research has examined the effect of display related factors on users' spatial task performance in the context of static, dynamic and interactive presentations. Three sets of experiments in these respective contexts were conducted to explore the influence of image type, display size, viewing distance, physiological cues, interface device and travel modes on distance estimate and spatial memory tasks. For distance perception, results revealed that the effect of image type depends on the context of presentations, the type of asymmetrical distances and image resolution. The effect of display size in static and dynamic presentations is consistent with the results of previous investigations. However, results from evaluations conducted by the author have indicated that other factors such as viewing distance and physiological cues were also accountable. In interactive presentations, results indicated that display size had different effects on different users whereby familiarity with display size may influence user's performance. Similarly, it was shown that a commonly used interface device is more useful and beneficial for user's spatial memory performance in the VE than the less familiar ones. In terms of travel mode, the natural method of movement available in the real world may not necessary be better than the unnatural movement which is possible in the VE. The results of investigations reported in this thesis contribute towards knowledge and understanding on factors affecting spatial awareness in the real and VE. In particular, they highlight the influence of these factors in space and distance perception in different contexts of VE presentations which will serve as important scientifically based guidelines for designers and users ofVE applications

    The Effect of Anthropometric Properties of Self-Avatars on Action Capabilities in Virtual Reality

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    The field of Virtual Reality (VR) has seen a steady exponential uptake in the last decade and is being continuously incorporated into areas of popular interest like healthcare, training, recreation and gaming. This steady upward trend and prolonged popularity has resulted in numerous extravagant virtual environments, some that aim to mimic real-life experiences like combat training, while others intend to provide unique experiences that may otherwise be difficult to recreate like flying over ancient Egypt as a bird. These experiences often showcase highly realistic graphics, intuitive interactions and unique avatar embodiment scenarios with the help of various tracking sensors, high definition graphic displays, sound systems, etc. The literature suggests that estimates and affordance judgments in VR scenarios such as the ones described above are affected by the properties and the nature of the avatar embodied by the user. Therefore, to provide users with the finest experiences it is crucial to understand the interaction between the embodied self and the action capabilities afforded by it in the surrounding virtual environment. In a series of studies aimed at exploring the effect of gender matched body-scaled self-avatars on the user\u27s perception, we investigate the effect of self-avatars on the perception of size of objects in an immersive virtual environment (IVE) and how this perception affects the actions one can perform as compared to the real world. In the process, we make use of newer tracking technology and graphic displays to investigate the perceived differences between real world environments and their virtual counterparts to understand how the spatial properties of the environment and the embodied self-avatars affect affordances by means of passability judgments. We describe techniques for creation and mapping VR environments onto their real world counterparts and the creation of gender matched body-scaled self-avatars that provides real time full-body tracking. The first two studies investigate how newer graphical displays and off-the-shelf tracking devices can be utilized to create salient gender matched body-scaled self-avatars and their effect on the judgment of passability as a result of the embodied body schema. The study involves creating complex scripts that automate the process of mapping virtual worlds onto their real world counterparts within a 1cm margin of error and the creation of self-avatars that match height, limb proportions and shoulder width of the participant using tracking sensors. The experiment involves making judgments about the passability of an adjustable doorway in the real world and in a virtual to-scale replica of the real world environment. The results demonstrated that the perception of affordances in IVEs is comparable to the real world but the behavior leading to it differs in VR. Also, the body-scaled self-avatars generated provide salient information yielding performance similar to the real world. Several insights and guidelines related to creating veridical virtual environments and realistic self-avatars were achieved from this effort. The third study investigates how the presence of body-scaled self-avatars affects the perception of size of virtual handheld objects and the influence of the person-plus-virtual-object system created by lifting the said virtual object on passability. This is crucial to understand as VR simulations now often utilize self-avatars that carry objects while maneuvering through the environment. How they interact with these handheld objects can influence what they do in critical scenarios where split second decisions can change the outcome like combat training, role-playing games, first person shooting, thrilling rides, physiotherapy, etc. It has also been reported that the avatar itself can influence the perception of size of virtual objects, in turn influencing action capabilities. There is ample research on different interaction techniques to manipulate objects in a virtual world but the question about how the objects affect our action capabilities upon interaction remains unanswered, especially when the haptic feedback associated with holding a real object is mismatched or missing. The study investigates this phenomenon by having participants interact with virtual objects of different sizes and making frontal and lateral passability judgments to an adjustable aperture similar to the first experiment. The results suggest that the presence of self-avatars significantly affects affordance judgments. Interestingly, frontal and lateral judgments in IVEs seem to similar unlike the real world. Investigating the concept of embodied body schema and its influence on action-capabilities further, the fourth study looks at how embodying self-avatars that may vary slightly from your real world body affect performance and behavior in dynamic affordance scenarios. In this particular study, we change the eye height of the participants in the presence or absence of self-avatars that are either bigger, smaller or the same size as the participant. We then investigate how this change in eye height and anthropometric properties of the self-avatar affects their judgments when crossing streets with oncoming traffic in virtual reality. We also evaluate any changes in the perceived walking speed as a result of embodying altered self-avatars. The findings suggest that the presence of self-avatars results in safer crossing behavior, however scaling the eye height or the avatar does not seem to affect the perceived walking speed. A detailed discussion on all the findings can be found in the manuscript

    Understanding the immersive experience: Examining the influence of visual immersiveness and interactivity on spatial experiences and understanding

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    Advances in computer graphics have enabled us to generate more compelling 3D virtual environments. 'Immersive experience' in these environments result from a combination of immersion and interactivity. As such, various disciplines have started adopting 3D technology for enhancing spatial understanding and experience. But the impact of the immersive experience on spatial understanding and experience remains unclear. This study utilized a controlled, between-subjects experiment to systematically manipulate a virtual reality system's technology affordances (stereoscopy, field of view, and navigability) and measure their impact. Participants, N=120, explored a virtual office and completed a questionnaire on the experience and tasks evaluating their understanding of the space. The results indicated that visual immersion had the greatest impact on understanding but, better experiences were gained when visual immersion was combined with greater interactivity. These findings support the notion the immersive experience is important for the comprehension of virtual spaces. This study overall served to provide insight into the role of the immersive experience on the comprehension of virtual spaces. The findings advance theories of spatial presence and immersion, support the use of methods which look at technology as affordances rather than entities, and support the use of 3D technology for communicating spatial information as in the case of architecture and fire-fighter training

    An Empirical Evaluation of Visual Cues for 3D Flow Field Perception

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    Three-dimensional vector fields are common datasets throughout the sciences. They often represent physical phenomena that are largely invisible to us in the real world, like wind patterns and ocean currents. Computer-aided visualization is a powerful tool that can represent data in any way we choose through digital graphics. Visualizing 3D vector fields is inherently difficult due to issues such as visual clutter, self-occlusion, and the difficulty of providing depth cues that adequately support the perception of flow direction in 3D space. Cutting planes are often used to overcome these issues by presenting slices of data that are more cognitively manageable. The existing literature provides many techniques for visualizing the flow through these cutting planes; however, there is a lack of empirical studies focused on the underlying perceptual cues that make popular techniques successful. The most valuable depth cue for the perception of other kinds of 3D data, notably 3D networks and 3D point clouds, is structure-from-motion (also called the Kinetic Depth Effect); another powerful depth cue is stereoscopic viewing, but none of these cues have been fully examined in the context of flow visualization. This dissertation presents a series of quantitative human factors studies that evaluate depth and direction cues in the context of cutting plane glyph designs for exploring and analyzing 3D flow fields. The results of the studies are distilled into a set of design guidelines to improve the effectiveness of 3D flow field visualizations, and those guidelines are implemented as an immersive, interactive 3D flow visualization proof-of-concept application

    Size and shape constancy in consumer virtual reality

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    With the increase in popularity of consumer virtual reality headsets, for research and other applications, it is important to understand the accuracy of 3D perception in VR. We investigated the perceptual accuracy of near-field virtual distances using a size and shape constancy task, in two commercially available devices. Participants wore either the HTC Vive or the Oculus Rift and adjusted the size of a virtual stimulus to match the geometric qualities (size and depth) of a physical stimulus they were able to refer to haptically. The judgments participants made allowed for an indirect measure of their perception of the egocentric, virtual distance to the stimuli. The data show under-constancy and are consistent with research from carefully calibrated psychophysical techniques. There was no difference in the degree of constancy found in the two headsets. We conclude that consumer virtual reality headsets provide a sufficiently high degree of accuracy in distance perception, to allow them to be used confidently in future experimental vision science, and other research applications in psychology

    Peripheral visual cues and their effect on the perception of egocentric depth in virtual and augmented environments

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    The underestimation of depth in virtual environments at mediumield distances is a well studied phenomenon. However, the degree by which underestimation occurs varies widely from one study to the next, with some studies reporting as much as 68% underestimation in distance and others with as little as 6% (Thompson et al. [38] and Jones et al. [14]). In particular, the study detailed in Jones et al. [14] found a surprisingly small underestimation effect in a virtual environment (VE) and no effect in an augmented environment (AE). These are highly unusual results when compared to the large body of existing work in virtual and augmented distance judgments [16, 31, 36–38, 40–43]. The series of experiments described in this document attempted to determine the cause of these unusual results. Specifically, Experiment I aimed to determine if the experimental design was a factor and also to determine if participants were improving their performance throughout the course of the experiment. Experiment II analyzed two possible sources of implicit feedback in the experimental procedures and identified visual information available in the lower periphery as a key source of feedback. Experiment III analyzed distance estimation when all peripheral visual information was eliminated. Experiment IV then illustrated that optical flow in a participant’s periphery is a key factor in facilitating improved depth judgments in both virtual and augmented environments. Experiment V attempted to further reduce cues in the periphery by removing a strongly contrasting white surveyor’s tape from the center of the hallway, and found that participants continued to significantly adapt even when given very sparse peripheral cues. The final experiment, Experiment VI, found that when participants’ views are restricted to the field-of-view of the screen area on the return walk, adaptation still occurs in both virtual and augmented environments

    Aerospace medicine and biology: A continuing bibliography with indexes (supplement 359)

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    This bibliography lists 164 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during Jan. 1992. Subject coverage includes: aerospace medicine and physiology, life support systems and man/system technology, protective clothing, exobiology and extraterrestrial life, planetary biology, and flight crew behavior and performance
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