PHYSICAL ACTIVITY IN VIRTUAL REALITY

The purpose of this conference is to discuss about research on human physical activity based on Virtual Reality (VR). VR 1) offers a unique compromise between control and ecological property of the studied situation, 2) enables to enrich/modify the physical environment, 3) provides control on the multisensory feedback given to the user, 4) and has the potential to enhance motivation and increase the number of repetition in motor skills training. Recent democratisation of immersive technologies, with the development of cheap interactive devices for videogames, has encouraged research in this domain. In this conference, we will address examples of perception-action coupling analysis based on VR, will analyse how technical choices could affect the behaviour of the studied subjects, and will expose perspectives in motor skills training based on VR

Biomechanical Analysis of Anticipation of Elite and Inexperienced Goalkeepers to Distance Shots in Handball

The objective of this study was to evaluate the anticipation time and kinematic factors in the movement of goalkeepers’ center of mass when making a long-distance throw in handball. The sample group was composed of 14 goalkeepers and field players. A force platform was used to measure the force of the goalkeepers’ reaction movements, while the throwers’ movements were recorded with high-speed cameras. The expert goalkeepers began to move 193 ± 67 ms before the ball was released, with a 67% success rate of interception. The inexperienced goalkeepers began their movement 209 ± 127 ms with a 24% success rate. The time taken by expert goalkeepers to begin a vertical movement of their CM, relative to the moment of the ball’s release, was less than the time taken by inexperienced goalkeepers (77 ± 70 vs. 141 ± 108 ms respectively). The analysis of the velocity and movement indicates that expert goalkeepers wait longer before moving than do inexperienced goalkeepers

The use of virtual reality head-mounted displays within applied sport psychology

This is the author accepted manuscript. The final version is available from Taylor & Francis (Routledge) via the DOI in this record.Virtual reality (VR) technology has been employed within several domains such as medicine, education, and the military. Nonetheless, there is limited research examining how VR can supplement applied sport psychology practice. This article provides the reader with an understanding of key components and concepts associated with VR head-mounted displays (HMDs). Subsequently, a range of possible applications within applied sport psychology are discussed, such as the training of perceptual-cognitive skills, relaxation strategies, and injury rehabilitation. Thereafter, the practicalities of using VR HMDs are outlined, and recommendations are provided to applied sport psychology practitioners wishing to embed this technology within their practice

The Effects of Pictorial Realism, Delay of Visual Feedback, and Observer Interactivity on the Subjective Sense of Presence

Two experiments examined the effects of pictorial realism, observer interactivity, and delay of visual feedback on the sense of presence. Subjects were presented pairs of virtual enviornments (a simulated driving task) that differed in one or more ways from each other. After subjects had completed the second member of each pair they reported which of the two had produced the greater amount of presence and indicated the size of this difference by means of a 1-100 scale. As predicted, realism and interactivity increased presence while delay of visual feedback diminished it. According to subjects\u27 verbal responses to a postexperiment interview, pictorial realism was the least influential of the three variables examined. Further, although some subjects reported an increase in the sense of presence over the course of the experiment, most said it reamined unchanged or became weaker

3D Virtual Worlds and the Metaverse: Current Status and Future Possibilities

Moving from a set of independent virtual worlds to an integrated network of 3D virtual worlds or Metaverse rests on progress in four areas: immersive realism, ubiquity of access and identity, interoperability, and scalability. For each area, the current status and needed developments in order to achieve a functional Metaverse are described. Factors that support the formation of a viable Metaverse, such as institutional and popular interest and ongoing improvements in hardware performance, and factors that constrain the achievement of this goal, including limits in computational methods and unrealized collaboration among virtual world stakeholders and developers, are also considered

Proxemics with multiple dynamic characters in an immersive virtual environment

An experiment was carried out to examine the impact on electrodermal activity of people when approached by groups of one or four virtual characters at varying distances. It was premised on the basis of proxemics theory that the closer the approach of the virtual characters to the participant, the greater the level of physiological arousal. Physiological arousal was measured by the number of skin conductance responses within a short time period after the approach, and the maximum change in skin conductance level 5 s after the approach. The virtual characters were each either female or a cylinder of human size, and one or four characters approached each subject a total of 12 times. Twelve male subjects were recruited for the experiment. The results suggest that the number of skin conductance responses after the approach and the change in skin conductance level increased the closer the virtual characters approached toward the participants. Moreover, these response variables were inversely correlated with the number of visits, showing a typical adaptation effect. There was some evidence to suggest that the number of characters who simultaneously approached (one or four) was positively associated with the responses. Surprisingly there was no evidence of a difference in response between the humanoid characters and cylinders on the basis of this physiological data. It is suggested that the similarity in this quantitative arousal response to virtual characters and virtual objects might mask a profound difference in qualitative response, an interpretation supported by questionnaire and interview results. Overall the experiment supported the premise that people exhibit heightened physiological arousal the closer they are approached by virtual characters

Real-time retrieval for case-based reasoning in interactive multiagent-based simulations

The aim of this paper is to present the principles and results about case-based reasoning adapted to real- time interactive simulations, more precisely concerning retrieval mechanisms. The article begins by introducing the constraints involved in interactive multiagent-based simulations. The second section pre- sents a framework stemming from case-based reasoning by autonomous agents. Each agent uses a case base of local situations and, from this base, it can choose an action in order to interact with other auton- omous agents or users' avatars. We illustrate this framework with an example dedicated to the study of dynamic situations in football. We then go on to address the difficulties of conducting such simulations in real-time and propose a model for case and for case base. Using generic agents and adequate case base structure associated with a dedicated recall algorithm, we improve retrieval performance under time pressure compared to classic CBR techniques. We present some results relating to the performance of this solution. The article concludes by outlining future development of our project

Visual Perception of Dynamic Properties and Events: Collisions and Throws

The central topic of this dissertation is visual perception of dynamic events. The topic is worth of interest, as witnessed by its long tradition in the history of Experimental Psychology, starting with the seminal work of Albert Michotte (1881 - 1965) on phenomenal causality. Thus, the topic I chose is not original in itself. However, a distinctive element of novelty in my dissertation is the use of Computer Graphics techniques as a means for creating realistic experimental stimuli in psychological experiments. Besides the advantage of reducing the gap between laboratory experiments and everyday experience, this may reveal the importance of experimental variables which traditionally have been ignored in research on visual perception of dynamic events. The reader should be informed that this dissertation is characterized by various lines of research, which are intrinsically connected with the central topic of visual perception of dynamic events. In some of the experiments, I investigate visual perception of dynamic events, whereas in others I investigate cognition of the same events. Two distinct dynamic events will be especially studied: horizontal collisions and throws. Moreover, the results of the experiments will be discussed not only in relation to their theoretical implications for psychological models, but also in relation to their potential applications to Physics education and Computer Graphics. As a result, the content of the dissertation is quite heterogeneous, but I hope to provide the reader with a broad and multidisciplinary perspective on the subject at hand. The dissertation is composed of five chapters, which may be divided into three groups. (i) In Chapters 1-3, after a presentation of the theoretical background of visual perception of dynamic events, I investigate the influence of dynamic properties of virtual objects on visual perception of horizontal collisions. The results of this research are important for the old and still active debate on phenomenal causality. (ii) In Chapter 4 I present a research on Naïve Physics of horizontal collisions between virtual spheres differing in simulated mass and velocity. In this chapter I take a more cognitive (rather than perceptual) perspective on dynamic events, investigating how people reason about the proposed physical event. (iii) In Chapter 5, I present a research on visual perception of virtual throwing animations, which are complex and rarely studied dynamic events. This chapter stands out for its multidisciplinary nature, as in it I discuss how the results can be applied to Computer Graphics. The research presented in this last chapter has been conducted as a part of my doctorate studies when I was a visiting PhD student at the Graphics, Vision, and Visualisation Group at Trinity College Dublin, where I collaborated with Professor Carol O’Sullivan and Doctor Ludovic Hoyet, who are computer scientists working on applications of visual perception to Computer Graphics. In more detail, in Chapter 1 I discuss the theoretical background of visual perception of dynamic events and phenomenal causality. Firstly, I focus on Michotte’s classical work. Secondly, I discuss some prominent issues which have been debated for a long time in this field of research. Lastly, I present White’s schema-matching model of visual perception of dynamic events, discussing its differences and similarities as compared with Michotte’s model. This chapter is intended to serve as a theoretical point of reference for the entire dissertation. In Chapter 2 I discuss the hypothesis that visually perceived dynamic properties of objects involved in dynamic events do influence visual perception of the dynamic events themselves. Firstly, I try to confute two popular arguments against this hypothesis. Then, I highlight the evolutionary advantage of visual perception of dynamic properties, discussing their possible influence on visual perception of dynamic events. Lastly, I discuss Runeson’s KSD model in relation to the presented hypothesis. In Chapter 3 I present three experiments which confirm the hypothesis discussed in Chapter 2. In particular, I show that simulated material (Experiment 1) and size (Experiments 2 and 3) of virtual objects involved in horizontal collisions strongly influence how observers perceive the event. I also discuss the theoretical implications of these findings by referring to Michotte’s and White’s models. In Chapter 4 I present a research on Naïve Physics of horizontal collisions. Firstly, I discuss the general importance of studying Naïve Physics for improving basic education in Physics. Secondly, I present Information Integration Theory and Functional Measurement methodology as suitable tools for the assessment of students’ intuitive knowledge of physical events, evidencing their advantages over multiple-choice surveys. Lastly, I present two experiments (conducted using Information Integration Theory and Functional Measurement) on Naïve Physics of horizontal collisions between simulated spheres differing in size, velocity, and material. The importance of the results for Physics instruction will also be discussed. Finally, in Chapter 5 I present a research on visual perception of edited virtual throwing animations. First I discuss the relations between visual perception of dynamic events (human motion in particular) and Computer Graphics. Then, I present two experiments on observers’ sensitivity to anomalies in realistic virtual throwing animations, discussing the importance of the results for videogames and movies industry

Reading the future from body movements – anticipation in handball

In speed-based sports that require fast reactions, the most accurate predictions are made once the players have seen the ball trajectory. However, waiting for the ball trajectory does not leave enough time for appropriate reactions. Expert athletes use kinematic information which they extract from the opponent’s movements to anticipate the ball trajectory. Temporal occlusion, where only a part of the full movement sequence is presented, has often been used to research anticipation in sports. Unlike many previous studies, we chose occlusion points in video-stimuli of penalty shooting in handball based on the domain-specific analysis of movement sequences. Instead of relying on randomly chosen occlusion points, each time point in our study revealed a specific chunk of information about the direction of the ball. The multivariate analysis showed that handball goalkeepers were not only more accurate and faster than novices overall when predicting where the ball will end up, but that experts and novices also made their decisions based on different kinds of movement sequences. These findings underline the importance of kinematic knowledge for anticipation, but they also demonstrate the significance of carefully chosen occlusion points