Conference Paper

Exaggeration of Avatar Flexibility in Virtual Reality

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Conference Paper

Exaggeration of Avatar Flexibility in Virtual Reality

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Abstract

Empowerment of movement through superhuman strength and flexibility is a staple of action video game design. However, relatively little work has been done on the same in the context of Virtual Reality and exergames, especially outside the most obvious parameters such as jumping height and locomotion speed. We contribute a controlled experiment (N=30) of exaggerating avatar flexibility in a martial arts kicking task. We compared different settings for a nonlinear mapping from real to virtual hip rotations, with the aim of increasing the avatar's range of movement and kicking height. Our results show that users prefer medium exaggeration over realistic or grossly exaggerated flexibility. Medium exaggeration also yields significantly higher kicking performance as well as perceived competence and naturalness. The results are similar both in 1st and 3rd person views. To the best of our knowledge, this is the first study of exaggerated flexibility in VR, and the results suggest that the approach offers many benefits to VR and exergame design.

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... This can be applied in both traditional video games and exergames (games that require require physical activity). Empowered, exaggerated movement in exergames and virtual reality has been shown to support competence [13,17], which is a core component crucial to motivating people in general [7,9], in games [31], and in exercise [20,30]. ...
... Our work adds to a line of movement empowerment research in exergames, mixed-reality games, and virtual reality games. Exergame movement empowerment research has progressed from boosting a player's movement in the game world with physics simulation [15], to mixed-reality empowerment that uses digital manipulation and physical devices like trampolines and electrically-assisted bikes [1,16,18], and more recently to user studies that demonstrate positive effects on autonomy and competence [13,17]. Jumping height and locomotion speed are common forms of exaggeration [15,17,18]. ...
... Jumping height and locomotion speed are common forms of exaggeration [15,17,18]. But, exaggerated fexibility has also been recently demonstrated [13]. Focus on fexibility and strength may be motivated by boredom caused by the requirement to repeat the same movements over and over again [29] or motivated by the fact that strength and fexibility develop very slowly in the real world. ...
Conference Paper
Insufficient physical activity motivation is a major public health problem. Exergames-games requiring physical exertion-can be designed to support motivation. For example, granting superhuman movement abilities to players has been shown to support one's feeling of competence, an innate human need and a core intrinsic motivation factor posited by self-determination theory. In this paper, we present Super Stomp, a multiplayer mixed-reality trampoline game that empowers movement by exaggerating jump height both in the real world and in the game. We contribute a novel dual-trampoline game system and game mechanics for implementing engaging multiplayer gameplay. This provides an exemplar of satisfying the challenging constraints that real-world movement empowerment technology can impose on exergame movement safety and feasibility. We further contribute insights into the effect of empowering movement on need satisfaction through an in-the-wild study involving 26 participants who played Super Stomp at an indoor activity park.
... Trackers were placed on front feet, on the upper back of the subject's shoes. Sensor placement on shoes allows for accurate tracking of feet motion [28]. ...
... Trackers were placed on front feet, on the upper back of the subject's shoes. Sensor placement on shoes allows for accurate tracking of feet motion [28]. A Unity3D (Unity Technologies, San Francisco, CA, USA) program was developed to display a virtual walkway within the VR headset (VIVE HTC PRO, Valve Corporation, Bellevue, WA, USA) paired with STEAM VR v020 [29]. ...
... VIVE sensors placed on participants' foot upper back similar to reference[28]. (a,b)The VIVE trackers are circled in green. The sensors were secured with an attachment tied to the shoes and oriented to face in the direction of the toes for consistency in measurement. ...
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Ageing, disease, and injuries result in movement defects that affect daily life. Gait analysis is a vital tool for understanding and evaluating these movement dysfunctions. In recent years, the use of virtual reality (VR) to observe motion and offer augmented clinical care has increased. Although VR-based methodologies have shown benefits in improving gait functions, their validity against more traditional methods (e.g., cameras or instrumented walkways) is yet to be established. In this work, we propose a procedure aimed at testing the accuracy and viability of a VIVE Virtual Reality system for gait analysis. Seven young healthy subjects were asked to walk along an instrumented walkway while wearing VR trackers. Heel strike (HS) and toe off (TO) events were assessed using the VIVE system and the instrumented walkway, along with stride length (SL), stride time (ST), stride width (SW), stride velocity (SV), and stance/swing percentage (STC, SWC%). Results from the VR were compared with the instrumented walkway in terms of detection offset for time events and root mean square error (RMSE) for gait features. An absolute offset between VR- and walkway-based data of (15.3 ± 12.8) ms for HS, (17.6 ± 14.8) ms for TOs and an RMSE of 2.6 cm for SW, 2.0 cm for SL, 17.4 ms for ST, 2.2 m/s for SV, and 2.1% for stance and swing percentage were obtained. Our findings show VR-based systems can accurately monitor gait while also offering new perspectives for VR augmented analysis.
... Increasing the movement of the animation, the user's visual perception of graphics can be enhanced. Specifically, exaggerated movement can lead to more memorable perception than non-exaggerated movement [28]. Therefore, we propose the exaggerated-feedback to improve the perceptual effect of the target phonemes in both audio and visual modalities. ...
... This inspires us to provide personalized feedback. As for exaggerated feedback, Antti et al. [28] contributed a controlled experiment of exaggerating the teaching avatar's flexibility in a kicking task. The experimental results demonstrate that users prefer exaggerated results over original ones. ...
... different pronunciation proficiencies) and how to define the best set of feedback. Our idea of involving exaggerated feedback and our system of determining the best set of exaggeration parameters can be beneficial for the general area of computer-aided language learning [25,29,66,77] and exaggerated feedback [28] systems in HCI. ...
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Second language (L2) English learners often find it difficult to improve their pronunciations due to the lack of expressive and personalized corrective feedback. In this paper, we present Pronunciation Teacher (PTeacher), a Computer-Aided Pronunciation Training (CAPT) system that provides personalized exaggerated audio-visual corrective feedback for mispronunciations. Though the effectiveness of exaggerated feedback has been demonstrated, it is still unclear how to define the appropriate degrees of exaggeration when interacting with individual learners.To fill in this gap, we interview {100 L2 English learners and 22 professional native teachers} to understand their needs and experiences. Three critical metrics are proposed for both learners and teachers to identify the best exaggeration levels in both audio and visual modalities. Additionally, we incorporate the personalized dynamic feedback mechanism given the English proficiency of learners. Based on the obtained insights, a comprehensive interactive pronunciation training course is designed to help L2 learners rectify mispronunciations in a more perceptible, understandable, and discriminative manner. Extensive user studies demonstrate that our system significantly promotes the learners' learning efficiency.
... Their results suggest that "movement empowerment may support autonomy, competence, and relatedness". A related project by Granqvist et al. [10] explored hyperrealistic avatar flexibility in a martial arts VR game. They found that a medium degree of hyperrealistic flexibility was preferred over realism or strong exaggeration. ...
... We argue that the decrease in perceived risk could have mitigated distraction from this worry, thus increasing immersion. Our results are particularly interesting in the context of related work by Granqvist et al. [10] on hyperrealistic avatar flexibility; here too, a moderate degree of hyperrealism was preferred over realism (as well as stronger degrees of hyperrealism). ...
Conference Paper
One of the great benefits of virtual reality (VR) is the implementation of features that go beyond realism. Common “unrealistic” locomotion techniques (like teleportation) can avoid spatial limitation of tracking, but minimize potential benefits of more realistic techniques (e.g. walking). As an alternative that combines realistic physical movement with hyper-realistic virtual outcome, we present JumpVR, a jump-based locomotion augmentation technique that virtually scales users’ physical jumps. In a user study (N=28), we show that jumping in VR (regardless of scaling) can significantly increase presence, motivation and immersion compared to teleportation, while largely not increasing simulator sickness. Further, participants reported higher immersion and motivation for most scaled jumping variants than unscaled jumping. Our work shows the feasibility and benefits of jumping in VR and explores suitable parameters for its hyper-realistic scaling. We discuss design implications for VR experiences and games.
... Customizing and using an avatar with greater muscle definition was associated with more physical endurance on a subsequent handgrip exercise task (Lee-Won et al., 2017). Another study found that exaggerated depiction of the flexibility of a body-tracked avatar in a virtual reality exergame increased the feeling of self-presence and performance of the game player (Granqvist et al., 2018). ...
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This study examined the effects of customization and intuitiveness of control on the feeling of identification and embodiment, and the actual running performance of game players after playing a digital runner game developed for this research. A 2 (avatar design: customized vs. not customized) × 2 (avatar controls: intuitive vs. not intuitive) within-subjects experiment (N = 44) found that playing the game with a customized avatar increased identification with and embodiment in the avatar. However, using unintuitive controls with a customized avatar diminished the feeling of identification. Customizing an avatar increased identification with and embodiment in the avatar. However, using unintuitive controls with a customized avatar diminished the feeling of identification. Further, participants’ running performance was significantly hindered in the customized avatar and unintuitive controls condition, compared to the other conditions. The expectation that identification and embodiment would mediate the effect of avatar customization and control intuitiveness on physical activity was not supported. Together, these results suggest that avatar customization and control intuitiveness should be prioritized when designers intend to use video games to promote post-game physical activity.
... Bowman et al. [21] have suggested the design of hyper-natural or magic techniques that reduce naturalness or realism or "enhance natural interactions to make them more powerful". Similar perspectives have been reflected in what Lehtonen et al. [91] term movement empowerment: exaggerated, "superhuman abilities" in movement-based digital games (e.g., [59,66,80,178]). ...
Conference Paper
Researchers reference realism in digital games without sufficient specificity. Without clarity about the dimensions of realism, we cannot assess how and when to aim for a higher degree of realism, when lower realism suffices, or when purposeful unrealism is ideal for a game and can benefit player experience (PX). To address this conceptual gap, we conducted a systematic review using thematic synthesis to distinguish between types of realism currently found in the digital games literature. We contribute qualitative themes that showcase contradictory design goals of realism/unrealism. From these themes, we created a framework (i.e., a hierarchical taxonomy and mapping) of realism dimensions in digital games as a conceptual foundation. Our themes and framework enable a workable specificity for designing or analyzing types of realism, equip future work to explore effects of specific realism types on PX, and offer a starting point for similar efforts in non-game applications.
... For example, providing motion capture animations or video recordings for characters with ad hoc rigs is almost impossible, and producing hand-designed animations for such character is expensive and time-consuming. Plus, using real-life videos for producing reference motions is not very suitable for games, where exaggeration in movements is frequently used to encourage the feeling of empowerment for the players [9]. Last but not least, such data-driven approaches can only be used for synthesizing movements whose reference motion is available; so they cannot be used for producing novel movements. ...
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Animation and machine learning research have shown great advancements in the past decade, leading to robust and powerful methods for learning complex physically-based animations. However, learning can take hours or days, especially if no reference movement data is available. In this paper, we propose and evaluate a novel combination of techniques for accelerating the learning of stable locomotion movements through self-imitation learning of synthetic animations. First, we produce synthetic and cyclic reference movement using a recent online tree search approach that can discover stable walking gaits in a few minutes. This allows us to use reinforcement learning with Reference State Initialization (RSI) to find a neural network controller for imitating the synthesized reference motion. We further accelerate the learning using a novel curriculum learning approach called Termination Curriculum (TC), that adapts the episode termination threshold over time. The combination of the RSI and TC ensures that simulation budget is not wasted in regions of the state space not visited by the final policy. As a result, our agents can learn locomotion skills in just a few hours on a modest 4-core computer. We demonstrate this by producing locomotion movements for a variety of characters.
... Established desktop VR devices, such as the HTC Vive (63) and Oculus Rift (42), are most commonly used in the papers reviewed followed by mobile device powered HMDs, e.g. Samsung Gear VR (9) and Google Cardboard (4). 3 publications did not report the device used. ...
... Moreover, iVR games can offer benefits such as increased perceived competence and the feeling of body movements that are more in line with how we perform exercise in the real world. Participants have described exaggerated movements to be natural, fun, and empowering [24]. Furthermore, exercising in iVR has been found to be an effective intervention to increase enjoyment and motivation than standard televisions or monitors [8,25], where enjoyment and motivation are, in turn, linked to increased adherence to physical exercises in general [26][27][28]. ...
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Background Although full-body seated exercises have been studied in a wide range of settings (ie, homes, hospitals, and daycare centers), they have rarely been converted to seated exergames. In addition, there is an increasing number of studies on immersive virtual reality (iVR) full-body gesture-based standing exergames, but the suitability and usefulness of seated exergames remain largely unexplored. Objective This study aimed to evaluate the difference between playing a full-body gesture-based iVR standing exergame and seated exergame in terms of gameplay performance, intrinsic motivation, and motion sickness. MethodsA total of 52 participants completed the experiment. The order of the game mode (standing and sitting) was counterbalanced. Gameplay performance was evaluated by action or gesture completion time and the number of missed gestures. Exertion was measured by the average heart rate (HR) percentage (AvgHR%), increased HR%, calories burned, and the Borg 6-20 questionnaire. Intrinsic motivation was assessed with the Intrinsic Motivation Inventory (IMI), whereas motion sickness was assessed via the Motion Sickness Assessment Questionnaire (MSAQ). In addition, we measured the fear of falling using a 10-point Likert scale questionnaire. ResultsPlayers missed more gestures in the seated exergame than in the standing exergame, but the overall miss rate was low (2.3/120, 1.9%). The analysis yielded significantly higher AvgHR%, increased HR%, calories burned, and Borg 6-20 rating of perceived exertion values for the seated exergame (all P
... There is a limited number of studies that have focused on ability empowerment in VR. Granqvist et al. [9] explored the empowered flexibility of the avatar in a martial arts VR game and found that a medium degree of empowered flexibility was preferred over realism or strong exaggeration of users' power. Ioannou et al. [12] explored a jump-and running-in-place application with applied forward motion in a VR exergame and found increased immersion and motivation of players when they played with their ability empowered. ...
Preprint
Physical activity or exercise can improve people's health and reduce their risk of developing several diseases; most importantly, regular activity can improve the quality of life. However, lack of time is one of the major barriers for people doing exercise. High-intensity interval training (HIIT) can reduce the time required for a healthy exercise regime but also bring similar benefits of regular exercise. We present a boxing-based VR exergame called VirusBoxing to promote physical activity for players. VirusBoxing provides players with a platform for HIIT and empowers them with additional abilities to jab a distant object without the need to aim at it precisely. In this paper, we discuss how we adapted the HIIT protocol and gameplay features to empower players in a VR exergame to give players an efficient, effective, and enjoyable exercise experience.
... There is a limited number of studies that have focused on ability empowerment in VR. Granqvist et al. [9] explored the empowered flexibility of the avatar in a martial arts VR game and found that a medium degree of empowered flexibility was preferred over realism or strong exaggeration of users' power. Ioannou et al. [12] explored a jump-and running-in-place application with applied forward motion in a VR exergame and found increased immersion and motivation of players when they played with their ability empowered. ...
... For partial upper-limb tracking, consumer devices including hand-held controllers such as Oculus Touch or HTC VIVE controllers and Motion Sensing devices such as Kinect and Leap Motion controller are widely used [27]. Granqvist et al. [12] used HTC VIVE controllers with inverse kinematics for partial upperlimb tracking. However, the hand-held controller can only track the position of the hand and cannot give the position information of the ngers. ...
Preprint
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Backgrounds: Transferring behaviors of a human’s upper-limbs to an avatar is widely used in the field of virtual reality rehabilitation. To realize the transfer, movement tracking technology is required. Traditionally, wearable tracking devices are used to do the tracking, however the devices are expensive and cumbersome. Recently, non-wearable upper-limb tracking solutions are proposed, which are cheaper and more comfortable to interact. But most of the existing products cannot track full upper-limbs including both the arms and all the fingers, which limits the motion paradigm and further may lead to limited rehabilitation effect. Methods: In this paper, a novel method was first proposed for full avatar’s upper-limb control which integrates the fine finger motion and the arm wide range motion. Then, based on the method, a Virtual Reality Rehabilitation System (VRRS) was developed for upper-limb rehabilitation. To test the performance of VRRS, two experiments were designed. First, in order to investigate the effect of VRRS on virtual body ownership, agency, location of the body and usability, we compared it with the partial upper-limb tracking method based on Leap Motion controller (LP) in same virtual environments. Then, to study the feasibility of VRRS in rehabilitation, we recruited 16 stroke patients and split them into two groups: the experimental group and the control group. Each group consisted 8 patients, with and without employing VRRS respectively. Results: The control of full avatar’s upper-limbs improved the users’ senses on body ownership, agency and location of the body. The users preferred to use VRRS. In addition, although the upper-limb motor function of patients from both groups were improved, the difference between the FM scores tested on the first day and the last day of the experimental group was more significant than that of the control group. Conclusions: VRRS based on the proposed method for full avatar’s upper-limbs control was developed, which improved the user experience on embodiment and effectively improved the rehabilitation effect for upper-limbs of stroke patients. Trial registration:The study was registered at the First Affiliated Hospital of Jinan University Identifier: KY-2020-036; Date of registration - June 01, 2020.
... Another work by Mueller et al. [55] examines a design space for social bodily play experiences which reveals the playful opportunities between bodies. Additionally, there have been many other studies that look into the efectiveness of body movements [35], embodiment [25] and experiences through movements [54], and the infuence of a second body [57]. Apart from games, somaesthetic design also has a close connection with wearables and the body. ...
... For partial upper-limb tracking, consumer devices, including hand-held controllers such as Oculus Touch or HTC VIVE controllers, and motion sensing devices, such as Kinect and Leap Motion controllers, are widely used [10]. Granqvist et al. [11] used HTC VIVE controllers with inverse kinematics for partial upper-limb tracking. However, the hand-held controller can only track the position of the hand and cannot provide information about the position of the fingers. ...
Article
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Background The transfer of the behaviors of a human’s upper limbs to an avatar is widely used in the field of virtual reality rehabilitation. To perform the transfer, movement tracking technology is required. Traditionally, wearable tracking devices are used for tracking; however, these devices are expensive and cumbersome. Recently, non-wearable upper-limb tracking solutions have been proposed, which are less expensive and more comfortable. However, most products cannot track the upper limbs, including the arms and all the fingers at the same time, which limits the limb parts for tracking in a virtual environment and may lead to a limited rehabilitation effect. Methods In this paper, a novel virtual reality rehabilitation system (VRRS) was developed for upper-limb rehabilitation. The VRRS could track the motion of both upper limbs, integrate fine finger motion and the range of motion of the entire arm and map the motion to an avatar. To test the performance of VRRS, two experiments were designed. In the first experiment, we investigated the effect of VRRS on virtual body ownership, agency and location of the body and usability in 8 healthy participants by comparing it with a partial upper-limb tracking method based on a Leap Motion controller (LP) in the same virtual environments. In the second experiment, we examined the feasibility of VRRS in upper-limb rehabilitation with 27 stroke patients. Results VRRS improved the users’ senses of body ownership, agency, and location of the body. The users preferred using the VRRS to using the LP. In addition, we found that although the upper limb motor function of patients from all groups was improved, the difference between the FM scores tested on the first day and the last day of the experimental group was more significant than that of the control groups. Conclusions A VRRS with motion tracking of the upper limbs and avatar control including the arms and all the fingers was developed. It resulted in an improved user experience of embodiment and effectively improved the effects of upper limb rehabilitation in stroke patients. Trial registration The study was registered at the First Affiliated Hospital of Jinan University Identifier: KY-2020–036; Date of registration: June 01, 2020.
... VR and martial arts were also combined to find whether exaggerated movements inside a VR simulation enhanced an interactive martial arts experience. The results indicated a medium exaggerated flexibility in the VR simulation was optimal and enjoyed most by the player (Granqvist et al., 2018). Thus, previous research show success in using VR to embody and teach martial arts in digital VR spaces. ...
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... Players have been tracked while jumping on a trampoline [48,55] or performing martial arts [42], showing exaggerated player movements on large screens. Player flexibility has been exaggerated using VR in a martial arts kicking task, by augmenting range of movement and kicking height [40]. VPA has also been utilised for navigation in VR by walking, allowing users to amplify their virtual speed [52] or enlarge their virtual body relative to the virtual world [62]. ...
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Four studies apply self-determination theory (SDT; Ryan & Deci, 2000) in investigating motivation for computer game play, and the effects of game play on well-being. Studies 1–3 examine individuals playing 1, 2 and 4 games, respectively and show that perceived in-game autonomy and competence are associated with game enjoyment, preferences, and changes in well-being pre- to post-play. Competence and autonomy perceptions are also related to the intuitive nature of game controls, and the sense of presence or immersion in participants’ game play experiences. Study 4 surveys an on-line community with experience in multi-player games. Results show that SDT’s theorized needs for autonomy, competence, and relatedness independently predict enjoyment and future game play. The SDT model is also compared with Yee’s (2005) motivation taxonomy of game play motivations. Results are discussed in terms of the relatively unexplored landscape of human motivation within virtual worlds.
Conference Paper
Cognitive factors such as distance- and speed perception play an important role when it comes to human performance during bodily exercise. Especially for bike training, deception of distance and speed can have a positive influence in one's performance and add to effective training. In this paper we investigate the performance of participants exposed to speed deception in virtual reality environments controlled by a training bike. With DeceptiBike we created a bike simulator that allows to manipulate speed perception via visual- and haptic cues. Our results show that we effectively can increase the users speed by 15.2% without the user noticing the effect. Our findings highlight the possibility of speed deception as a method for novel bike training systems.
Conference Paper
Manipulating a virtual object with appropriate passive haptic cues provides a satisfying sense of presence in virtual reality. However, scaling such experiences to support multiple virtual objects is a challenge as each one needs to be accompanied with a precisely-located haptic proxy object. We propose a solution that overcomes this limitation by hacking human perception. We have created a framework for repurposing passive haptics, called haptic retargeting, that leverages the dominance of vision when our senses conflict. With haptic retargeting, a single physical prop can provide passive haptics for multiple virtual objects. We introduce three approaches for dynamically aligning physical and virtual objects: world manipulation, body manipulation and a hybrid technique which combines both world and body manipulation. Our study results indicate that all our haptic retargeting techniques improve the sense of presence when compared to typical wand-based 3D control of virtual objects. Furthermore, our hybrid haptic retargeting achieved the highest satisfaction and presence scores while limiting the visible side-effects during interaction.
Conference Paper
This paper seeks to expand the understanding of gravity as a powerful but underexplored design resource for movement-based games and play. We examine how gravity has been utilized and manipulated in digital, physical, and mixed reality games and sports, considering five central and gravity-related facets of user experience: realism, affect, challenge, movement diversity, and sociality. For each facet, we suggest new directions for expanding the field of movement-based games and play, for example through novel combinations of physical and digital elements. Our primary contribution is a structured articulation of a novel point of view for designing games and interactions for the moving body. Additionally, we point out new research directions, and our conceptual framework can be used as a design tool. We demonstrate this in 1) creating and evaluating a novel gravity-based game mechanic, and 2) analyzing an existing movement-based game and suggesting future improvements.
Article
Video games can empower their players beyond reality, giving them extraordinary abilities. We investigate a novel class of games that provide empowerment in both the real and the virtual world, in this case using a trampoline as part of the human-computer interface. We studied whether novice trampoline jumpers can learn trampolining skills while playing a platform jumping game implemented using computer vision and a screen placed near the trampoline. 29 participants were divided into three groups: self-training, a game with a normal jump height, and a game with an exaggerated jump height. Performance was tested in pre, post and follow-up tests. All groups improved their performance significantly. The game was considered more engaging and the mean flow questionnaire (SFSS) result with games was significantly higher than with self-training. The study shows that trampoline games can be fun, intuitive to play and basic trampolining skills can be improved while playing the game. A game is more engaging than self-training and extra empowerment, such as jump height exaggeration, enhances the experience. The exaggeration did not adversely affect jumping performance, and half of the participants did not even consciously notice it, which suggests that there is considerable design freedom for manipulating the player's movements in trampoline games.
Article
This study investigated the relationship of sport participation to perceived competence. Perceived competence is considered to be an important determinant of achievement motivation and behavior. Male and female fourth and fifth graders (N = 143) were given Harter's (Note 1) Perceived Competence Scales and were interviewed to determine their involvement in organized sport activities. Further, the children were asked to give their perceptions of competence relative to teammates, general attributions about sport outcomes, and their persistence and expectancies of future success. The results revealed that participants in organized sports were higher in perceived competence, were more persistent, and had higher expectations of future success. The causal attributions of participant children were ability oriented and generally supported the perceived competence findings. The results are consistent with the statement that perceived competence in physical skills has an important influence on the participation and ...
Article
Animating in-game avatars using real time motion capture data is highly appealing and is becoming more widespread due to the accessibility of researchers and developers to consumer priced depth sensors [Microsoft Kinect 2010]. Depth sensors allow for a cheap and robust motion capture solution which can be naturally adapted to games. However, in spite of the many advantages of using real-time motion capture data for animating avatars in games, there are two major challenges. The first is due to the limitations of the current tracking techniques in producing smooth, noise free, accurate animation in real-time. The second, and more acute problem, stems from the fact that in most games, the movements of the animated avatar are expected to be more expressive than the player's actual movements. In such cases, one would like to visually enhance the player's motion to display exaggerated or even super-natural motions.
Article
It is generally accepted that augmented feedback, provided by a human expert or a technical display, effectively enhances motor learning. However, discussion of the way to most effectively provide augmented feedback has been controversial. Related studies have focused primarily on simple or artificial tasks enhanced by visual feedback. Recently, technical advances have made it possible also to investigate more complex, realistic motor tasks and to implement not only visual, but also auditory, haptic, or multimodal augmented feedback. The aim of this review is to address the potential of augmented unimodal and multimodal feedback in the framework of motor learning theories. The review addresses the reasons for the different impacts of feedback strategies within or between the visual, auditory, and haptic modalities and the challenges that need to be overcome to provide appropriate feedback in these modalities, either in isolation or in combination. Accordingly, the design criteria for successful visual, auditory, haptic, and multimodal feedback are elaborated.
Article
Tested the notions, based on a competence motivation theory by S. Harter (1978), that perceptions of competence are related to particular motives children have for sport participation. 67 children (8–16 yrs old) involved in youth gymnastic programs were administered the Physical, Social, and Cognitive subscales of the Perceived Competence Scale and a motives-for-gymnastic-participation questionnaire. Results show that children high in perceived physical competence were more motivated by skill development reasons, and gymnasts high in perceived social competence were more motivated by the affiliation aspects of sport when compared to their low perceived competence counterparts. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Conference Paper
This paper presents Kick Ass Kung-Fu, a martial arts game installation where the player fights virtual enemies with kicks and punches as well as acrobatic moves such as cartwheels. Using real-time image processing and computer vision, the video image of the user is embedded inside 3D graphics. Compared to previous work, our system uses a profile view and two displays, which allows an improved view of many martial arts techniques. We also explore exaggerated motion and dynamic slow-motion effects to transform the aesthetic of kung-fu movies into an interactive, embodied experience. The system is described and analyzed based on results from testing the game in a theater, in a television show, and in a user study with 46 martial arts practitioners.
Conference Paper
This paper describes the design of a perceptual user interface for controlling a flying cartoon-animated dragon in QuiQui’s Giant Bounce, a physically and vocally interactive computer game for 4 to 9 years old children. The dragon mimics the user’s movements and breathes fire when the user shouts. The game works on a PC computer equipped with practically any lowcost microphone and webcam. It is targeted for uncontrolled real-life environments such as homes and schools.
Article
It is common for athletes striving to achieve maximal effort to exercise in the presence of a visible clock. It is implicitly assumed that calibration of the clock is normal (i.e. accurate). This study was designed to test the effect of secretly manipulating the clock calibration on maximal effort as measured by endurance times in cycle ergometry. Twelve subjects (6 male and 6 female) each undertook three identical rides to exhaustion on a cycle ergometer. In one the clock was normally calibrated, in another it was calibrated 10% faster, and in the third 10% slower. Tests were conducted double blind and in fully counterbalanced orders within gender. Clocked endurance times were recorded, and later converted to real times. Analysis of clocked times revealed no significant effects. Over all subjects, real endurance times showed a significant calibration effect, being on average 18.3% (73.4s) longer when the clock ran slow, compared to normal, and 20.5% (80.8s) longer when compared to fast. Because males exercised significantly longer than females, separate analyses reveal that the calibration effect was only significant in males, 27.7% (143.2s) and 29.7% (151.2s), respectively, and present but not significant in females, 1.3% (3.6s) and 3.8% (10.5s), respectively. These results suggest that, when deceived by a visible clock running slower than normal, times to exhaustion on the cycle ergometer were significantly longer in male subjects.
SDT: Questionnaires: Intrinsic motivation inventory (IMI)
  • El Deci
  • Ryan
EL Deci and RM Ryan. 2015. SDT: Questionnaires: Intrinsic motivation inventory (IMI). (2015).
Mixed reality empowerment for enhancing physical exercise
  • Perttu Hämäläinen
  • Raine Kajastila
Perttu Hämäläinen and Raine Kajastila. 2014. Mixed reality empowerment for enhancing physical exercise. In Proceedings of the CHI 2014 HCI and Sports Workshop. http://mobilelifecentre.org/content/ chi-workshop-hci-and-sports.
Jumping on a trend: Indoor trampoline parks are big business for owners and fun and exercise for kids and adults
  • Jessica Peralta
Jessica Peralta. 2016. Jumping on a trend: Indoor trampoline parks are big business for owners, and fun and exercise for kids and adults. http:
Michael Phelps: Push the Limit. Video game
  • Microsoft
Microsoft. 2011. Michael Phelps: Push the Limit. Video game.. (2011).
Self-presence, explicated: body, emotion, and identity. Handbook of Research on Technoself
  • Rabindra Ratan
Rabindra Ratan. 2012. Self-presence, explicated: body, emotion, and identity. Handbook of Research on Technoself: Identity in a Technological Society (2012), 322.
Utilizing gravity in movement-based games and play
  • Joe Perttu Hämäläinen
  • Raine Marshall
  • Richard Kajastila
  • Florian Floyd Byrne
  • Mueller
Haptic retargeting: Dynamic repurposing of passive haptics for enhanced virtual reality experiences
  • Mark Mahdi Azmandian
  • Hrvoje Hancock
  • Eyal Benko
  • Andrew D Ofek
  • Wilson
The motivational pull of video games: A self-determination theory approach. Motivation and emotion
  • Scott Richard M Ryan
  • Andrew Rigby
  • Przybylski