Examensarbete 30hp August 2016

Virtual Reality sickness during immersion: An investigation of potential obstacles towards general accessibility of VR technology.

A controlled study for investigating the accessibility of modern VR hardware and the usability of HTC Vive’s motion controllers. Dongsheng Lu

Abstract People call the year of 2016 as the year of . As the world leading tech giants are releasing their own Virtual Reality (VR) products, the technology of VR has been more available than ever for the mass market now. However, the fact that the technology becomes cheaper and by that reaches a mass-market, does not in itself imply that long-standing usability issues with VR have been addressed. Problems regarding (MS) and motion control (MC) has been two of the most important obstacles for VR technology in the past. The main research question of this study is: “Are there persistent universal access issues with VR related to motion control and motion sickness?” In this study a mixed method approach has been utilized for finding more answers related to these two important aspects. A literature review in the area of VR, MS and MC was followed by a quantitative controlled study and a qualitative evaluation. 32 participants were carefully selected for this study, they were divided into different groups and the quantitative data collected from them were processed and analyzed by using statistical test. An interview was also carried out with all of the participants of this study in order to gather more details about the usability of the motion controllers used in this study. The results of this study has validated several existing frameworks for VR. And in conclusion, this study has also shown that both previous motion sickness experiences and gender factors weren’t significant in terms of general accessibility issues on PCVR platforms. There are hints showing that the VR technology on PC platform could be universal accessible, since both of the quantitative and qualitative results has provided some evidences supporting this finding. However, more similar studies need to be carried out in order to identify more possible factors that would give an impact on user experiences in VR. The results of this study has also given implications of that today’s VR technology is developing on the right track and it could slowly become adopted by the mainstream and mass-market in the future.

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Acknowledgement First of all, I would say a great thank you to Annika, you have taken over my supervision during the time I have encountered a lot of difficulties even though you had a lot of other works to do. It was you who encouraged me and made me believe that this study can actually be done in time. And again thank you for all the help and guidance you have given me. I have learned a lot from you and your courses and you will always remain as my teacher, my professor and my mentor of life. My heartfelt gratitude to the department of Informatics and Media. The department purchased the device for me and made it possible so I could use the best and most recent released VR hardware available on the mass market, this helped me and this study to avoid a lot of uncertainties that might be caused by outdated hardware. Also thank you, Johan Nysjö of the IT Department, who lent me the instruments for pre-study. The pre-study has been an important part of my study as well, and your generosity is greatly appreciated. I would also like to thank all of the people who were involved in this study, the teachers, my friends, my classmates who gave me feedback and took their time to participate in this study, you all have been a very important part of this study.

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TABLE OF CONTENTS

CHAPTER PAGE

ABSTRACT ...... 2

ACKNOWLEDGEMENT ...... 3

1. INTRODUCTION ...... 6

1.1 PUPOSE AND RESEARCH QUESTION ...... 7

2. BACKGROUND ...... 9

2.1 VIRTUAL REALITY ...... 9

2.2 INPUT METHODS FOR VR ...... 9

2.3 HEAD MOUNTED DISPLAYS ...... 11

2.4 CLASSIFICATION OF THE RECENT VR HEADSETS ...... 11

2.5 IMMERSIONS & PRESENCE IN VR ...... 12

2.6 ROLE-PLAYING VIDEO GAMES & GAMING EXPERIENCES ...... 12

2.7 AVAILABLE VR HARDWARE FOR CONSUMERS ...... 12

3. PREVIOUS RESEARCH ...... 13

3.1 MOTION SICKNESS ...... 13

3.2 INDIVIDUAL DIFFERENCES AND SUSCEPTIBILITY ...... 14

3.3 IMOTION CONTROLLERS IN VR ...... 14

4. THEORY ...... 15

4.1 SENSORY CONFLICT THEORY ...... 15

4.2 POSTURAL INSTABILITY THEORY ...... 17

4.3 FLOW THEORY ...... 18

4.4 SENSORIMOTOR ADAPTATION ...... 19

5. METHOD ...... 20

5.1 MS MEASUREMENTS ...... 20

5.2 QUESTIONNAIRE (SSQ) ...... 20

5.3 PRE-STUDY ...... 21

5.4 METHOD APPLICATION ...... 23

5.4.1 TEST PARTICIPANTS ...... 23

5.4.2 MATERIALS AND EXPERIMENT LOCATION ...... 23

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5.4.3 SELECTING VIRTUAL ENVIRONMENT ...... 24

5.4.4 VANISHING REALMS: RITE OF STEEL...... 24

5.4.5 EXPERIMENT PROCEDURE ...... 25

6. RESULTS ...... 28

6.1 PARTICIPANT PROFILING ...... 28

6.2 RAW DATA FOR GROUP WITH PREVIOUS MS ...... 30

6.3 RAW DATA FOR GROUP WITHOUT PREVIOUS MS ...... 31

6.4 COMPARISON BETWEEN TWO GROUPS ...... 32

6.5 COMPARISON BETWEEN MALE AND FEMALE GROUPS ...... 34

6.6 COMPARISON OF AVERAGE VALUES OF OVERALL VR SICKNESS SYMPTOM SCORES...... 35

6.7 QUALITATIVE RESULTS ...... 36

7. DICUSSION ...... 38

7.1 SIGNIFICANT DIFFERENCE ...... 38

7.2 DETAILED EXPLANATION OF COLLECTED SCORES ...... 38

7.3 SUGGESTIONS FOR CURRENT MS MEASUREMENT STANDARD ...... 38

7.4 THE PROCESS OF SENSORIMOTOR ADAPTATION ...... 39

7.5 MOTION CONTROLLERS FOR VR CONTENTS ...... 39

7.6 LIMITATIONS CONTROLLERS FOR VR CONTENTS ...... 39

7.5 RECOMMENDATIONS FOR FUTURE WORK ...... 40

8. CONCLUSIONS ...... 41

9. REFERENCES ...... 43

10. APPENDICES ...... 46

APPENDIX A ...... 46

APPENDIX B ...... 47

APPENDIX C ...... 49

APPENDIX D ...... 52

APPENDIX E ...... 53

APPENDIX F ...... 55

APPENDIX G ...... 57

APPENDIX H ...... 58

APPENDIX I ...... 59

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1. Introduction Several tech giants have accounted for the release of their own VR products, therefore people call the year of 2016 as the year of Virtual Reality. According to an article by Paul Lamkin on wearable.com, Rift by , HTC vive by valve and HTC and PlayStation VR by seems are three of the most promising VR hardware in 2016. (P. Lamkin, 2016) There are of course many more different companies which are taking their steps into the VR industry. There are several evidences showing that VR is slowly getting adopted by the mainstream. Such as the announcement from Google on I/O 2016 and rumors about Apple’s secret VR project mentioned by Steven Rosenbaum on Forbes. These are the indications of the VR technology is here to stay. (S. Rosenbaum, 2016) According to the recent market research by Heather Bellini from Goldman Sachs, the VR /AR industry will generate a net worth of $80billion by 2025, which almost equals to the worth of today’s PC industry. (H. Bellini et al, 2016)

Fig. 1.1.1 The progression of Goldman Sachs base hardware and forecast from Goldman Sachs Global Investment Research. All of this points to the same direction that there is or will be a huge demand in the VR industry and the VR technology today is ready to rise and slowly become adopted by mainstream industries out on the market. At this point, we can see how promising the VR industry seems to be in the future. However, it is not clear if this rapidly increasing interest in VR is motivated by radical improvements in the quality of the technology, or just by the ability to produce affordable technology for the consumer market. VR history has been plagued by severe issues. The most serious issues relate to discomfort caused by motion sickness or a suitable way of interacting with VR systems. A well-known example in this case would be the “” released by in 1995. Virtual boy which claimed to be the first device that allow users to see true 3D graphics, they have been largely criticized as a commercial failure, and one of the biggest reason was the discomfort caused by motion sickness. (Lisa Foiles, 2014)

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Fig. 1.1.2 Illustration of Virtual Boy from 1995 Biocca (1992) have investigated closely if the simulator sickness will slow down the growth of virtual environment technology, in his book he has discussed how SS can be considered as an obstacle for VE systems. (F. Biocca, 1992). There is also another evidence showing that the issue of MS and SS have been an obstacle for VR or VE technology since 1950s. I am personally a VR enthusiast, and have had strong interests in VR technologies since I was very young. My previous research in the field was about the impact of HMDs on player’s in-game enjoyment, and this master thesis can be considered as a follow up study of my previous research where we had enormous amount of hardware limitations. The main reason that I initiated my thesis in this field is because I have seen some very successful examples in the industry and I personally possess a strong belief that VR technology can change the way of how we interact with different people, different systems and different sectors in the future. 1.1 Purpose and Research Question Since today’s VR industry is expanding rapidly and all the VR hardware are becoming more available for the mass market, it is important for us to know if this is a technology for everyone, or if there are people who cannot, and never will be able to use it. The results of this study will hopefully provide some answers to this problem. The purpose of this study is to have a better understanding of how and why can different people suffer from in immersive environment, and more importantly to find out if the modern VR technology is universal accessible or will there always be a group of people who will suffer from VR sickness. In this study I have contributed with exploring specific issues more in depth based on the background literature. We have known the existence of the issues related to motion sickness and interaction problems with VR technology, but we have never learned how large in scale these problems are and if there are any persistent universal access issues? Motion controllers are also an important part of the modern VR technology; it will allow users to use their natural body or hand movement to interact with different objects in virtual environments, which will expand their immersive experiences. (VRScout, 2016) The attractiveness of VR technology is not

7 all about visual, it is also about how you can interact with the virtual environment (VE). A proper input method is extremely important for VR technology. At this point, it is not clear about what kind of usability problems there are with the motion controllers used for interacting with VE. And also we do not yet know which kind of input method is most suitable for interaction in VR. Finally, in this study I will take a closer look at if people with previous motion sickness experiences are more vulnerable to VR environments compared to people who have not suffered from any motion sickness experiences before. The research question of this study in this case is: “Are there persistent universal access issues with VR related to motion control and motion sickness?”

It has been obvious obstacles in the past which have hindered the VR technology from being adopted by the mainstream. Therefore the results of this study would make a great contribution to the field and VR industry, since there are signs and evidences showing that the technology is slowly being adopted by the mainstream and mass-market. The ultimate goal of this study is to make the industry understand what kinds of obstacles we are facing in the near future, and more importantly the study will also make a contribution of concluding if VR is actually for everyone or not.

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2 Background 2.1 Virtual reality (VR) Traditional Virtual Reality is an artificial three dimensional virtual or immersive environment that is often generated by computers. Today’s VR refers more to the hardware Head Mounted Display (HMD) together with the supporting software. HMD generally refers to a display or a monitor that is worn on user’s head or integrated inside a helmet. It has been used in several areas including: surgical treatment, military simulations, education and other entertainment. (H. Bellini et al, 2016) Heather Bellini the business unit leader in Goldman Sachs believes that the modern VR technology have the potential to transform almost all industry we have today, (H. Bellini et al, 2016) and I’ certainly agree with her. The history of Virtual Reality can trace its way back to 1960s, when Morton Heilig the pioneer in Virtual Reality created the first VR prototype called “”, which was a machine that allow users to engage their multiple senses such as sight, sound, smell and touch. (M. Heilig US PATENT, 1962) Later on in 1968 Ivan Sutherland created the first VR/AR head mounted display with help from his student Bob Sproull. At that time the device was so heavy so that it had to be suspended on the ceiling in order to allow users to wear it, and the Virtual environment generated were really simply which was only consisted of wire frame models. (I. Sutherland, 1998) After the VR technology has been invented, it was mostly used in U.S military where soldiers used the technology as a simulation of different military tasks, and flight simulator used in U.S Air Force was one of the examples. (HIT Lab T. A. Furness III) Later on in 1980s, VR technology is slowly adopted by the entertainment sectors such as Arcade machines and theme parks. (Atari, 1999) (M. Mine, 2003)

Picture of Atari VR 2.2 Input methods for VR The motion sensors or tags located on different VR headsets is the essential part that made the VR head tracking possible. The system behind it which made this possible is known as 6DoF (Degrees of Freedom) That means you can look and move your head in X, Y and Z axis. The internal components which are used for head tracking can be different, some VR headsets are using , and magnetometer. But some other devices like PS VR and Oculus, they are taking the advantage of LED lights and invisible infrared lights which can be detected by the cameras, and make head tracking possible. (S. Charara, 2016) The first input method which involves body movements for VR devices can trace its origin back to 1977, when Dan Sandin, Richard Sayre and Thomas Defanti developed the first data glove in the world. It is also known as the which consisted of sensors that allow users to use their gesture and hand movements as an input method. (D. J. Sturman & D Zeltzer, 1994) The interaction in current VR applications and games are usually done by using a pair of devices called motion controllers. The motion controllers are often used as an input device for video games,

9 and it was first publically announced by Nintendo back in 2006. (K. Castaneda, 2006) Today’s modern motions controllers for VR are mainly consisting of sensors that can be detected by motions trackers. They can be accurately tracked in a 3D space, just like the recent VR headsets. (HTC Vive Teardown 2016) This allowed users to freely use their hand and arm movements to interact with the virtual environments, which can take their immersive experiences to the next level. Unlike the motion controllers, the or game console controllers that are currently existing on the market right now can also be considered as one input method for VR devices. Gamepads are usually compatible with PC or different game consoles such as , PlayStation, Nintendo Wii and etc. The classical gamepads are usually consisting of several buttons for interactions, but now there are more features and hardware involved, such as motion sensors, haptic feedback mechanisms and on different kinds of gamepads. (Nintendo Wii U 2016) One known example of using gamepads as input for VR devices is the product bundle of CV1 which includes a wireless Xbox controller. (Oculus.com, 2016) In order to reach an ultimate immersion experience using VR devices, it is often not enough by using only arm and hand movements for interactions. Therefore, there are a lot of third party companies and developers whom are trying to make the VR experiences even more realistic. And technology is one of them. Leap motion controllers are taking the advantage of two IR cameras and three infrared LEDS to track user’s exact hand movement. By using this technology user’s hand can be accurately tracked and synchronized in the . And in that sense, this would allow users to directly interact with virtual objects and environments with their own hand, gesture and finger movements. (Frank Weichert et al, 2013)

Pic. 2.2.1 Illustration of how Leap Motion technology can be used in VR products (slideshare.net) There are also some hardware devices that tracks feet and lower body movements, such as the . It is known as a VR treadmill where users can walk, run or even perform actions such as jumping and dodging. This provided the possibility for users to use their full body movement to interact with different virtual environments and games in 360°s of angle, in that sense it would bring the VR or immersive experience further to the next level. (Virtuix Omni 2016)

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Pic. 2.2.2 Illustration of how Virtuix Omni device can be used for VR products. (virtuix.com) 2.3 Head Mounted Displays (HMD) Head mounted displays (HMD) often refer to wearable displays which are often integrated in eyeglasses or helmets. The modern HDM are now often referred to , it includes motion tracking sensors, gyroscopes, accelerometers, that could track user’s head movements and directions. It is aimed to provide an immersive experience to the users, and some of the devices also include earphones, eye tracking and motion controllers which would also allow users to explore and interact in a virtual world by using head and their natural body movements. (B. Kuchera 2016) (S. Miles, 2015) There is also another kind of HMD or it is also known as Head up Display HUD which is also available out on the market. The main difference between these two types of HMD is that one of them which is mainly support Virtual Reality, does completely covers user’s vision using non transparent monitors. While the other one is most used in (AR) with a transparent display which does not block user’s visions. AR devices are consisting of transparent displays, cameras and sensors that help users to identify the objects they see in the real world and add graphics on top of that. (M. Rachel, 2012) 2.4 Classification of the recent VR headsets The VR technology have grown fast in the past of a few years since Oculus first announced their project on Kickstarter. Today, the VR headsets are not limited to one type any more, and it is also important for us to know the differences between each type of VR headsets. There are three main categories for the classification of the recent VR headsets, PC VR headsets, VR headsets and Standalone VR headsets. The PC VR headsets are the recent VR headsets which is used by connecting to a PC. That means it is not a functional device by itself, and it needs the quite powerful computing power from a modern PC, the most well-known PC VR headsets are Oculus Rift, HTC Vive, FOVE and OSVR. There is one additional type of VR headset which does not really belongs to PCVR category which is PlayStation VR. It is classified as an outlier where it need to be connected to a PS4 in order to use the device. (K. Carbotte, 2015) Unlike PC VR headsets, smartphone headsets (MobileVR) are taking another approach. Smartphone VR are often referred to the case or viewer which holds a smartphone. It is a lot cheaper than the existing PC VR headsets and it’s more widely adopted by the users today, a few examples would be , Samsung Gear VR, Zeiss VR One, Freefly VR and etc. (K. Carbotte, 2015)

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The third type of VR headsets are not really well-known today, but there are evidences have shown that these are starting to emerge in the mass market now. Unlike both of the types mentioned above, Standalone VR devices (StandaloneVR) are completely independent from any device like PC or Smartphone, it operates on its own and are powered by batteries. The representative devices of this type of VR headsets are Avegant Glyph, SulonQ, Idealens and Pico VR. All of the mentioned types of VR headsets do have their pros and cons, such as PC VR headsets are tethered, and the cables will often get into user’s way during an immersive experience, therefore in that sense Smartphone and standalone VR devices is better. But in the other hand, the Smartphone and standalone VR devices does not come with a powerful computing power that can render high quality images which will make HD graphics impossible for them. (M. Mattlund, 2015) 2.5 Immersions & presence in VR According to E. Adams the well-known game designer, there are mainly four different types of immersions including: Tactile immersion, Strategic immersion, Narrative immersion and spatial immersion. In my study only spatial immersion is related, that is when a user or player feels that he or she is completely immersed and feels that everything in the virtual environment is real. (S. Björk & J. Holopainen, 2004). This type of immersion is very similar to the concept of presence as well. The definition of presence by Barfield and Weghorst 1993, is “Virtual presence or occurs when attentional resources are allocated to stimulus events which are generated by a computer or associated technology” (W. Barfield et al, 1995 p.493). There are several hardware requirements in order to reach this form of spatial immersion according to Oculus VR and Valve. These requirements are: a wide angle of FOV, high resolution, high refresh rate, low pixel persistence, accurate tracking and low latency. These requirements for establishing presence are the research results obtained by the research team at Valve. (M. Abrash, 2014) 2.6 Role-Playing Video Games and Gaming experiences According to the Ernest Adams, a role-playing is where the player controls the action of an in-game character while immersed in a well-defined virtual world. RP video games are originated from traditional RP games with pen, paper and a game master. RPGs today have evolved into games with rich experiences and 3D graphics and with the VR technology today, it would provide the players with even more additional immersive and outstanding 3D experiences. (E. Adams & A. Rollings, 2003) In this study a Virtual Reality RPG game was selected to be used as a background material for testing user’s in-game immersive experiences. The reason behind the choice was mainly because of there are more contents and actions involved in this type of game which will make it easier to generalize later on. Such as an RPG game could include several elements from other game genres, such as FPS, Adventure, exploration and action. 2.7 Available VR hardware for consumers Device Platform Company Features Oculus Rift CV1 PC Facebook High resolution and 110° FOV Samsung Gear VR Smartphone Samsung Does not require PC and external GPU HTC Vive PC HTC & Valve Positional Tracking and enhanced movement

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PlayStation VR PS Sony High refresh rate 120Hz and low latency <18ms Avegant Glyph Standalone Avegant Portable Razer OSVR PC Razer Open source software and hardware Zeiss VR One Smartphone Zeiss Affordable price FOVE VR PC FOVE Eye tracking Star VR PC Star Breeze 210° FOV A list of the VR headsets available or will be available for the mass market soon. The hardware used in this study is HTC Vive, and it is the most recent released and the most up to date hardware available on the mass market, and of course is it also the most expensive device available now. The study was carried out in my private apartment where modern instruments and a recently purchased PC is used. By using these modern instruments and hardware it can efficiently eliminate any uncertainties that may cause by out dated hardware. The HTC Vive does come in a bundle where motion detectors and controllers are included. The refresh rate of the Vive headset is 90Hz and a resolution of 1080x1200 per eye. The device itself have more than 70 sensors including gyroscopes, accelerometers and laser sensors supported by the lighthouse technology. (E. Maiberg, 2015) Together with these two sets of base stations that tracks motions, users can utilize a maximum play area of 4.6mx4.6m with extremely accurate precision. (L. Kelion, 2015)

Fig. 2.6.1 An illustration of the hardware bundle used in this study. (HTC Vive) 3 Previous research 3.1 Motion sickness Motion sickness (MS) is a term of generally describing several discomfort symptoms such pallor, cold sweating, , and vomiting. (D. M. Johnson 2005). In modern era the most commonly experiences examples are car, sea and or even dizziness due spinning. (A. J. Benson, 2002) Today, we have already discovered several variant of it which are known as Cinerama, simulator, and virtual reality sickness that has emerged together with the recent release of modern VR products. VR sickness is also known as cybersickness. It is usually induced by exposure to virtual and immersive environments. And It causes symptoms such as nausea, dizziness, headache, sweating, which is similar to the symptoms from ordinary motion sickness. (LaViola Jr, J. J, 2000)

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3.2 Individual differences and susceptibility Kolasinski explained that there are some individual differences when people are exposed to simulated and virtual environments. (E. M. Kolasinski, 1995) Age is one of the difference. Recent study by J. Brooks el al have shown that people who are older than 50 years old are more likely to experience virtual reality sickness compared to younger adults. (J. O. Brooks et al, 2010) Gender is also one of the individual differences, explained by G. Park et al. They claimed that women are more vulnerable to virtual environments in in terms of MS or SS. In Kennedy et al’s (1983) paper they also made a similar claim that women are more susceptible than men, and the main reasons could be the hormone differences and that women have a wider field of view. (R. S. Kennedy et al, 1985) There are many more such similar individual differences, such as ethnicity, health condition and experience with the system etc. These factors are very important for my studies, and the related variables should be controlled for the most valid and reliable results. For this matter, I have created a background control questionnaire for each of the volunteers. All of the participants chosen for this study were carefully selected according to their profile and individual background, the reason of this is to avoid the uncertainties that may cause by individual differences. And according to their background I have distributed them into four different groups. They were evenly divided to male and female groups, and then they were divided into groups of participants who have had previous motion sickness experiences and participants with no such experiences. More details about the participants of the experiment can be found in method section. 3.3 Motion controllers in VR As mentioned before, motion controllers are one of the most common input method for interactions in VR. The motions controllers in fig 2.6.1 made by HTC are the controllers used in this study. According to my own research, there have not been any usability studies done on these type of controllers before, this could be because of the device bundle of HTC VIVE was recently released. And related studies have not been published yet. However, there has been some usability studies done on Nintendo Wii’s motion controllers. In this case the Wii controllers cannot be really considered as motion controllers developed for VR, because the use case is very different between VR and Wii. A usability study done by Philip Stubbs in University of Minnesota have concluded that the Wii remote was purposefully designed for enhancing user experiences based on D. Norman’s five principle of design. Stubs also argued that Wii remote also offers easy learnability, little need for recall of how it works, and offers user satisfaction through user interactivity and naturalness of the remote. One of the main purposes of this study is to try find out the usability problems of motion controllers for interactions in modern VR technologies. Motion controllers for HTC VIVE can also be considered as the first pair of for VR available for the mass market, since these devices are really new, it is even more important for us to identified the potential usability problems related to such devices. Finally, at this point we can clearly see that motion sickness is an issue related to VR technologies, and it might cause negative user experiences for some people due to individual differences. And also introducing motion controllers could have a positive impact on VR experiences, if the controllers are correctly and well designed.

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4. Theory 4.1 Sensory Conflict Theory According to the Oxford dictionary of Psychology, the complete explanation of sensory conflict theory is “A proposed explanation for motion sickness according to which passive movement creates a mismatch between information relating to orientation and movement supplied by the visual and the vestibular systems, and it is this mismatch that induces feelings of nausea.”

Fig. 4.1.1 An illustration of the inner ear () Sensory conflict theory is one of the theories that explains that cause of Motion Sickness (MS) or Simulator Sickness (SS). The sensory conflict theory was first proposed by Claremont in 1931, after that the theory was revised by many different authors. (C. A. Claremont, 1931). What Claremont proposed in 1931 was mainly about how we would experience SS if the signals from different sensory organs (e.g. ears, eyes.) does not match. Later on in 1978 Reason argued against Claremont that the original theory wasn’t appropriate, mainly because of he claimed that signals from various sense organs have different standards, in terms of dynamic response and coding type. And it creates conflict or not between the sensory organs are actually depends upon context and previous sensory motor experience. (C. M. Oman, 1989). The sensory conflict theory was further explained by Reason in 1978, and he also create a neural mismatch model for explaining the motion sickness phenomenon.

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Fig. 4.1.2 Neural mismatch model diagram proposed by J. T. Reason (1978) Johnson (2005) explained that when perceived motion is not correlated with the forces transmitted by our vestibular system (e.g. the signals from the ear and the eyes received by the brain is different) then there’s a higher chance of experiencing SS. In the other hand if our motion or movements are in agreement of our visual perception then there’s a less risk of experiencing SS. (D. M. Johnson, 2005) I think this has provided some extent of useful insights to the existing VR content or game designers. I have combined the explanation of Johnson 2005 and my own interpretation and created a simplified version of a diagram that explains MS, SS and CS. (Cybersickness or VR sickness)

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Fig.4.1.3 Simplified version of Sensory conflict explanation diagram. The sensory conflict theory is mainly used as a framework of understanding the motion sickness and simulator sickness. In my study I will be closely investigating on VR sickness or Cyber sickness; however, Johnson 2005 explained that the same theory can also be applied for VR sickness to better understand how and why it can occur. (D. Johnson, 2005) And this is the main reason that sensory conflict theory was used as one of the foundations for this study. 4.2 Postural Instability theory Postural instability theory was first hypothesized by Riccio and Stoffregen 1991, they explained that motion sickness was caused by instability in control of the posture of the body or its segments. (Riccio and Stoffregen 1991) According to other literature, postural instability can also be one of the symptoms of virtual reality sickness. (E. M. Kolasinski, 1995) The definition of postural instability by Riccio and Stoffregen is “the state in which uncontrolled movements of the perception and action systems are minimized” (Riccio and Stoffregen, 1991 p.202) This is however very different from the original definition of postural instability which is relegated to medical and physiological studies where a frank loss of body control (such as falling) is involved. (Riccio and Stoffregen, 1991) In contrast, postural stability is when a person processes the stable stance of their body and body segments. This can be measured by using two different types of floor-based body test. The first one is static postures, it is measured in terms of how long one person can hold a certain body posture. The second one is dynamic test, where people need to perform e.g. a walking task, and check for any imbalances (S. Cobb 1999) An typical example is Sharpened Romberg test which was mentioned earlier in the text. Cobb (1999) has also mentioned in his paper that Sharpened Romberg test has been used for measuring postural instability by several works such as Hamilton et al (1989) and Takahashi et al. (1992) Johnson (2005) argued that to effectively reduce MS or SS, users need to attain a certain level of postural stability, and best way of doing that is laying on a flat surface where most of us can attain the maximum amount of postural stability (Johnson, 2005)

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Postural instability theory is indirectly related to my study because the test for measuring postural stability can also be used for checking the signs and symptoms of MS or Virtual reality sickness. But in my study the test was not used for several reasons. Instead of performing postural stability tests, test participants were asked to fill out a questionnaire which follows the standards of Simulator Sickness Questionnaire developed by Kennedy et al in 1993. The purpose of using questionnaires was mainly because of it can be more efficient and easier during the data collecting process, and it would also be easier to do perform the data analysis as well. 4.3 Flow theory The concept of flow was created by the Hungarian psychologist Mihaly Csikszentmihalyi. The term of flow can refer to a highly involved state, where concentration motivations are important aspects of flow. (M. Csikszentmihalyi, 1992) The concepts of flow are recognized in many fields such as occupational therapy, artistic works, or even video gaming. The theory is related to my study in terms of flow in video gaming, and it also expected to see a state of flow during the time of my experiment. It is not often easy to reach the state of flow, which is mainly because of the balance between difficulty of the task and skill level of the user need to be kept at a steady level. For instance, if a game is too hard and a player’s skill level is too low, then the state of flow will not be reached, in the other hand, if the difficulty and player’s skill level are both high, then the state of flow will be more likely to present. (C. Murphy, 2011). The flow model created by Csikszentmihalyi (1997) can perfectly explain this phenomenon.

Fig. 4.3.1 Mental state in terms of challenge level and skill level. Flow model by M. Csikszentmihalyi “finding flow” (1997) In my study it is expected that the participants will engage in a state of flow during their test trials of their immersive experiences. The assumption is based on the fact that the VR headset and the motion controllers will bring enhanced visual experiences and naturalness interaction to the participants. This is normally also depended on the individual differences of each participant, but in this study a few precautions have taken for avoiding such uncertainties. Any external or testing environment problem could have an impact on user’s flow and it would affect their immersive experiences.

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4.4 Sensorimotor Adaptation Sensory adaptation is the change of responsiveness to constant stimuli. (M. A. Webster, 2012) A personal example would be that: I will feel the water in the bath tub is too hot when I first dipped my body in it, but after spending less than a minute, my body have adapted to the heat and will no longer feel the water is too hot. The term of sensorimotor adaptation is often used in rehabilitation area. That is for instance when someone have been in an accident, maybe also lost a part of their body and need to recover their basic motor skills. The adaptation process can also be found in our everyday life, for example when you are using a friend’s which has a significant higher cursor speed, you will then feel uncomfortable, and resulting errors. But within a few minutes our brains and motor functions can quickly adapt to the new setting of that mouse cursor setting. However, when we return to our own computer we would immediately feel that the previous cursor setting was too slow, and would result errors again, this entire adaptation process is known as motor adaptation. (A. Bastian, 2008) In previous years, sensorimotor adaptation and VR technology were often used together for patient’s rehabilitation processes. In Adamovich et al’s article they claimed that using VR technology for training might be beneficial for neural functions (S. Adamovich, 2009) This is mainly because of VR technology can provide stimulus to patients, which will result a better training experience. It is also expected to see sensorimotor adaptation in my study. The reason of this is that the hardware used in this study is fairly new, and none of the test participants have ever tried it before. Therefore, this could be a totally new experience for them. But as mentioned before there are individual differences between each of the participant, and some of them may get really sick, while others won’t feel discomfort, and it is possible that it would require some time of the participants to adapt to this new technology and new VR experiences. The process itself can also be considered as a kind of sensorimotor adaptation. More of this will be explained and analyzed in the discussion part of the text.

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5. Method Performing controlled experiments has always been one of the methodology that interests me the most. For my Master thesis I have chosen a mixed method approach to find out two separate problems in the same investigation. The term of mixed method may refer to a recent methodology of research that integrates or mixing the quantitative and qualitative data in a single investigate or study. By using a methodology like this, it would allow researchers to have a more complete and efficient way of analyzing the data compared to doing two separate quantitative and qualitative studies. The methodology was mostly used in the field of social sciences but it has recently expanded to areas such as medical sciences and pharmacy. (Creswell & P. Clark, 2011) 5.1 MS Measurements There are different methods can be used for measuring motion sickness or simulator sickness. The standard way of measuring simulator sickness today is to use the Simulator Sickness Questionnaire (SSQ) made by R. S. Kennedy et al. in 1993 for U.S military. There is another method which is known as Sharpened Romberg Stance could also be used for measuring simulator sickness. This Romberg’s test involves user performing different body stances and the experimenter or observer will then check for if there are any body imbalances. In my study I have made my own version of a questionnaire for measuring VR sickness, which is inspired by the SSQ and the related literature. (R. S. Kennedy et al, 1993) All of the six major symptoms in VR sickness are included in the questionnaire. They are general discomfort, boredom, nausea, headache, disorientation and stomach awareness. (E. M. Kolasinski, 1995) Each of the symptoms have a scale from 1 to 5 where 1 is none, and 5 is severe. 5.2 Simulator Sickness Questionnaire (SSQ) Simulator Sickness Questionnaire was first developed by Kennedy et al. in 1993 for U.S Navy. They mainly used the SSQ for training pilots. Today this is still the standard for testing SS. The questionnaire is based on more than 1000sets of previous data and they have identified 27 different symptoms of SS. They are also classified in three different categories: Nausea, Oculomotor and Disorientation. The original SSQ are calculated by sub-scores of each category and the total score of SS. Each of the symptoms is rated in four different levels, none, slight, moderate and severe. (Kennedy et al, 1993)

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Fig. 5.2.1 Example of the symptoms and scores.(cybersickness.org) The SSQ made by Kennedy et al (1993) were both used in pre and post exposure of virtual environment. In my study I have decided to not let participants to fill in a questionnaire for pre- exposure. The main reason of this is because I was afraid of that once the participants have seen the symptoms they might get triggered during test. Questionnaire used in my study only the main expected symptoms are stated, this is mainly because of there are a lot of complicated words that might confuse the participants. So instead of including all the 27 symptoms, I have only included 5 main expected symptoms from Virtual reality sickness which are: general discomfort, boredom, nausea, headache, disorientation and stomach awareness. And this is based on the Kolasinski’s work where he explained the most common symptoms of cybersickness. (E. M. Kolasinski, 1995) In contrast, these terms or symptoms can be easily understood by the participants compared to the original version of the SSQ. In my post-exposure questionnaire, it does not only contain the expected symptoms, but it also includes some of the more general questions such as overall satisfaction, excitement, immersion and frustration which may help to analyze some more details of participant’s experiences. This study can be furtherly disabled into two sub investigations. First part is mainly about comparison of two sets of data and finding if there is a significant difference. The second part is consisted of qualitative questionnaire and interview where the users or the participants of this study will be able to have an open-ended discussing with the experimenter (me) regarding the general aspects and the usability of the motion controllers used in this study. 5.3 Pre-study The pre-study was carried out using an Oculus Rift DK2, which is 2 years older than the recently shipped one Oculus Rift CV1. Compared to the CV1, DK2 has lower resolutions and less sensitive

21 tracking sensors. The results obtained from the pre-study has served an important purpose for the rest of the study, this is mainly why the details of the pre-study has been included in the text.

Fig. 5.2.1 An illustration of Oculus Rift DK2 used in the pre-study (Oculus.com) After I have performed the Pre-study, I have gather a lot of information about how the method application could be further improved in the real study. According to the collected data and information from the pre-test, a more suitable version of VR sickness questionnaire need to be developed. A few attributes that seemed to be irrelevant in this case are: fatigue, drowsiness, sweating, confusion and vomiting. Since the test trials are going to be fairly short (under 30min), and the device will be used is recently released, therefore severe symptoms should not be expected. The pre-test participants also reported that it’s quite challenging to define the true meaning of the symptoms in the questionnaire. And also they felt several different questions had same meanings e.g. boredom and drowsiness, difficulty focusing, concentration difficulty and confusion, or nausea and dizziness. There is also a problem with question number 13, (see table 5.2.1) which was about most of the participants didn’t close their eyes during the test, so most of the participants just “guessed” what they would feel if they closed their eyes. The questionnaire which is going to be used in the real test should include very clear and diverse questions to avoid confusion. But still follows the concept of the original SSQ, which are divided into three big categories: Nausea, Oculomotor and Disorientation. In this case shorter and clearer questions would only bring advantages, that is also because of most of the participants will probably have difficulty to define those tricky terms, such as drowsiness, faintness, eyestrain etc. It will only result that they will start guessing instead of knowing the definition of the symptoms. Which can also lead to unreliable and inaccurate data. Another suggestion for improvements for the real test is that, to pick an appropriate VR content that require minimum amount of controls or have straight forward control options which will avoid confusion for the participants who lack of previous experiences. This could become better when using the HTC Vive device since there will be motion controllers involved which may provide a more straightforward controls for most of the VR contents.

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I think selecting the appropriate content for the real test is probably the real challenge here, because different people have different kinds of experiences and preferences. So I think it is hard to select something that would suit everyone’s taste. 5.4 Method Application In this section the execution and the details of the entire experiment procedure is going to be described in details. Many of the aspects have changed since the test plan was created and pre-study was done, the main reasons behind that was: as this study progressed, new limitations and problems were discovered so different improvements and adjustments needed to be done for a better result. 5.4.1 Test Participants For the formal test, there were in total of 32 volunteers selected as participants for this study. They are gender balanced and 50% of them have had previous motion sickness experiences before and 50% have not ever suffered from motion sickness. The participants are young group of adults between 20- 29 years old. Around 63% of the participants are studying in Master’s degree, and 34% of them are studying in Bachelor’s degree, the rest of the participants are studying in PhD degree. During the time when they have participated the test, 100% of them were healthy, and 100% of them have never tried playing a virtual reality role playing game before. Approximately 56% of the participants are from Europe while 44% of the participants were from Asia. When it comes to previous gaming experiences and familiarity of RPG’s they all had very different backgrounds. But however, that will not affect this study mainly because of it’s not the game which will be evaluated and tested, and secondly all of the participants have had no problems with the game because of everyone have received tips and continues instructions from me during the test. That means none of the participants have ever encountered any difficulties regarding the game itself, and no one have gotten stuck or frustrated anywhere in the game. 5.4.2 Materials and Experiment location As the study have progressed, I have discovered that the stationary computers in our Interaction lab is not even close to be able to run the HTC Vive device. That didn’t stop the study from going on, because of the experimenter owns a recently purchased PC that met the minimum requirement of HTC Vive. Considering the difficulty of transporting the heavy equipment and storing it at school, it was decided that the experiment location should be moved from department’s interaction lab to experimenter’s apartment instead. The Materials and instruments used in this study are: HTC Vive device bundle which include two Vive motion controllers, two base stations and one VR headset. The computer used for running the device has the graphic card of Nvidia GTX970 built in, which is the minimum requirement of running HTC Vive. The computer also comes with 16G RAM and the latest Intel i7 GPU which will make the VR experiences go smoothly. A Go Pro Hero4 was also used for recording the entire test trial of each of the participant. It was also used for recording the qualitative interview in the end as well. An external TV was also used for monitoring participant’s in-game actions, so the experimenter would be able to see actions done by the participants. There was also another tablet computer available for the participants to fill out the questionnaires. The laptop used in this study was a Surface Pro 3. 5.4.3 Selecting virtual environment The results and conclusions of this study is aimed to be easily generalized and contribute to many sectors such as the VR industry, game design industry and academia. So the most challenging part was about selecting the most appropriate game or virtual environment for this study.

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Finally, a virtual reality RPG was selected as a background material for the test, and for this matter I have purchased more than ten different games on and tested them out by myself and finally evaluated which one could be the best for this study. A VR RPG was selected for my study was mainly because of RPG’s are easier to generalize compared to any specific type of game. That could be anything from first person shooter, adventure to actions games and etc. The selected game for my study also involves several different experiences and moments which is related to FPS, adventure and action games, in this sense it is easier to generalize. Another reason has something to do with the mechanisms of this game, it was designed in a way so that player’s motions and body movements would match with the in-game actions and in this sense it would greatly reduce the likelihood of experiencing cybersickness or VR sickness. Other extreme examples or games could have been chosen for this study, but it is not my aim to recruit people to come here and make them experience the VR sickness, this was considered as one important aspect of this study, that people should also have fun and enjoy themselves while participating in this experiment. An example of a game that have a higher chance to make the participants sick is Elite: Dangerous. It is a game where players are allowed to drive their own spacecraft and explore the universes which is made based on our Milky Way galaxy. More extreme actions and movements are involved in this game and according to the sensory conflict theory this types of games may be the ones that players should avoid if they want the optimal VR experiences. 5.4.4 Vanishing Realms: Rite of Steel The games used in my study is called Vanishing Realms. It is one of the first VR RPG’s available on Steam store, and according to the ratings of the steam community it has an overwhelmingly positive feedback. This VR experience does allow players to explore in a mystic world and battle real-life sized monsters. (Steam store, 2016)

Fig. 5.4.4 A cover picture for the VR RPG game Vanishing Realms: Rite of steel. (vanishingrealms.com)

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Fig. 5.4.5 A picture illustration the in-game combat situation. (polygon.com)

Fig. 5.4.5 An illustration of the in-game environment. (http://store.steampowered.com/app/322770/) In this game, all of the participants were allowed to use the play area in the experiment location to freely move around and interact with in-game objects and environments using the Vive’s motion controller. And there are no real objectives in this game, so players can choose how they would like to spend their time inside the game. During the combat players can freely use their body movements to dodge enemy’s attacks or avoiding traps. There are many different objects that allow the players to pick up, and the main differences between traditional and VR RPG’s is mainly the use of different items and weapons. For instance, if the player wants to attack an enemy with a sword, the player only need to swing their arm to perform the action, and the same thing if they wanted to block enemy’s attacks. 5.4.5 Experiment procedure When the participants have arrived at the site of experiment, they will be informed with some general instructions. The main points of the instructions are:

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 This experiment is not about testing your gaming ability or in-game performances.  In this experiment you will be playing a VR RPG game during 30minutes of time.  You should use think a loud method to let the experimenter know how you feel, and how you think about different things that you are experiencing during the test.  You have the right to withdraw if you can’t handle the discomfort, and you may raise any concerns to the experimenter anytime during the test. After the instructions they will be reading through a consent form (see appendix A) and sign their names. This is the standard procedure of controlled study and it will ensure that they have understood the purpose of this study, and also making them aware of the risks of this study. Before they start they also need to fill out a background control questionnaire just to ensure that they are the appropriate participants for this study. The questionnaire is consisting of some personal information, and their previous motion sickness experiences and gaming experiences. When they put on the headset and prepared to start I will then ask if they would like to go through a tutorial that helps them to learn the basic knowledge of HTC Vive device and the controls of the Vive motion controllers. After the tutorial, I will then help the participants to start the game, where they need to go through player creation and in-game tutorial part which takes around 2 minutes. When they have first entered the first chapter of the game, I will then start the timer to record the time, and they will be informed that they will have 30 minutes of time to explore and play this game from now. During the time most of the participants used the think a loud method to let me know how they feel in general. However, there were a few participants seemed to be quiet. In such cases I will then ask them simple questions about how they are feeling, if they are experiencing any discomfort, how they think about the experience etc. By taking advantage of the think a loud method, I can quickly identify, when, who and where participants are experiencing discomfort and VR sickness. This has also been a crucial part of this study. After the test trial, they will be requested to fill out a post-exposure questionnaire to explain their general discomfort and overall experience. A semi-structured interview will then take place after that, where the experimenter will ask a few questions or start some small discussions regarding the Vive’s motion controllers. At last, the participants are requested to fill in the last questionnaire about the general aspects of the Vive motion controllers, this is for supporting the validity of their answers obtained from the interview.

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Pic. 5.2.6 A picture of the experiment location, where a play area of 2.9x2.5m was available for all of the test participants.

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6. Results 6.1 Participant profiling The pie charts below represent the characteristics of the test participants of this study. By the time they participated the test, they were all healthy so it will be certain that none of the discomfort emerged during this study were caused by other sickness or diseases. None of the participants have ever tried playing RPG using VR devices before, therefore it has ensured that this experience for them will be a totally new experience for all of the participants. Exactly half of the participants were male and the other half were female. And exactly half of the participants have had previous motion sickness experiences before and the rest have not ever suffered from motion sickness. At this point we can clearly see that the participants can be evenly divided into four groups, according to their individual motion sickness experience and gender.

Fig. 6.1.1 several pie charts illustrating the background of the participants. The charts below are illustrating participant’s previous gaming experiences and familiarity of RPGs. As the charts are showing, the participants have a distributed level of previous gaming experiences and familiarity of RPGs. This could be one of the limitations of this study because everyone is not on the same level when it comes to playing RPGs and video games. However, a precaution has been made. That is everyone will get hint, recommendations and guidance, so they would all know what to do and how to do some certain things inside the game. The materials shown here was directly taken from the results of Google survey which was used for collecting the raw data of this study.

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Fig. 6.1.2 two charts illustrating the previous gaming experiences and familiarity of RPG’s of the test participants. (x axis is familiarity while y axis is number of participants) In the following sections there will be several tables, graphs and charts displayed to compare the collected quantitative data. The processed qualitative data gathered from the interviews and questionnaires will also be displayed in this section. However, the raw data from the qualitative interviews will not be included. There are a few variables which will be included in the result tables and charts, which are: overall satisfaction, excitement, immersion and frustration. These data are collected to support the data collected from the virtual reality sickness symptoms to further analyze some of the details. All of the participants are divided into two groups which are gender balanced. Group A in this case is the group of participants who have experienced previous motions sickness experiences. And group B is the group of participants who have not experienced any sort of past motion sickness experience before. The collected scores have also been transformed a bit in the following sections as well. In the original post-exposure questionnaire answered by the participants, they have a symptom severity score scaled from 1 to 5 where 1 is none and 5 is severe. In the following sections, all the values have been lowered by 1, this because of it will become easier for the data analysis section later on. In this sense 0 will represent none in VR sickness symptom severity while score of 4 represents the maximum value of VR sickness symptoms.

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6.2 Raw data for Group with previous motion sickness experience: Table. 6.1.1 Raw data for Male participants of Group with previous MS P = Participant Severity: 0=None, 1=Slight, 2=Moderate, 3=Moderately severe, 4=Severe

Male P1 P2 P3 P4 P5 P6 P7 P8 General Discomfort 0 0 1 0 0 0 0 1 Boredom 0 0 0 0 0 0 0 0 Nausea 0 0 0 0 0 0 0 1 Headache 0 0 3 2 0 0 0 0 Disorientation 0 0 2 1 1 1 0 2 Stomach Awareness 0 0 0 0 0 0 0 0

Table 6.2.2 of Average severity for Male participants of Group with previous MS:

With previous MS Male General Discomfort 0.25 Boredom 0 Nausea 0.125 Headache 0.625 Disorientation 0.875 Stomach Awareness: 0

Table. 6.2.3 Raw data for Female participants of Group with previous MS P = Participant Severity: 0=None, 1=Slight, 2=Moderate, 3=Moderately severe, 4=Severe

Female P9 P10 P11 P12 P13 P14 P15 P16 General Discomfort 0 0 1 0 2 2 0 2 Boredom 0 0 0 0 0 2 0 0 Nausea 0 0 2 0 1 1 0 1 Headache 0 0 2 1 0 0 0 0 Disorientation 1 3 2 0 2 0 0 2 Stomach Awareness 0 0 1 0 0 2 3 0

Table 6.2.4 of Average severity for Female participants of Group with previous MS:

With previous MS Female General Discomfort 0.25 Boredom 0.625 Nausea 0.375 Headache 1.25 Disorientation 0.75 Stomach Awareness 0.875

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6.3 Raw data for Group without previous motion sickness experience: Table. 6.3.1 Raw data for Male participants of Group without previous MS Severity: 0=None, 1=Slight, 2=Moderate, 3=Moderately severe, 4=Severe

Male P1 P2 P3 P4 P5 P6 P7 P8 General Discomfort 1 0 0 0 0 1 0 0 Boredom 1 0 0 0 0 0 0 1 Nausea 1 0 2 0 0 0 0 0 Headache 0 0 1 0 0 0 0 0 Disorientation 3 0 0 0 0 1 2 0 Stomach Awareness 0 0 0 0 0 0 0 0

Table 6.3.2 of Average severity for Male participants of Group without previous MS:

Without Previous MS Male General Discomfort 0.25 Boredom 0.25 Nausea 0.325 Headache 0.125 Disorientation 0.75 Stomach Awareness 0

Table. 6.3.3 Raw data for Female participants of Group without previous MS. P = Participant Severity: 0=None, 1=Slight, 2=Moderate, 3=Moderately severe, 4=Severe

Female P9 P10 P11 P12 P13 P14 P15 P16 1. General Discomfort 0 1 0 2 1 0 1 0 2. Boredom 0 0 0 1 0 0 0 0 3. Nausea 0 1 0 2 0 0 0 0 4. Headache 0 0 0 0 0 1 0 0 5. Disorientation 0 1 2 1 0 1 0 0 6. Stomach Awareness 0 1 0 2 0 0 0 0

Table 6.3.4 of Average severity for Female participants of Group without previous MS:

Without Previous MS Male General Discomfort 0.625 Boredom 0.125 Nausea 0.375 Headache 0.125 Disorientation 0.625 Stomach Awareness 0.125

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6.4 Comparison between groups with and without previous motion sickness: In this section there will be mainly two different groups of data that will be compared with each other. First of all, Group A will be compared to Group B. And then there will also be a comparison between the gender groups in the section after. The average value of the VR sickness symptoms will be calculated and used for comparisons. The calculations of average severity of every VR sickness symptom from previous sections will be used in this section for being furtherly calculated and compared. In the following comparison sections, the “symptom” boredom will be excluded, this has been one support variable to help to identify the correlations between VR sickness and boredom. And also according to the literature boredom cannot be really considered as one of the symptoms of VR sickness. Table 6.4.1 Average severity values for Group with previous MS (Male and Female):

Group with previous MS General Discomfort 0.56 Nausea 0.38 Headache 0.5 Disorientation 1.06 Stomach Awareness 0.38

Table 6.4.2 Average severity values for Group without previous MS. (Male and Female):

Group without previous MS General Discomfort 0.44 Nausea 0.35 Headache 0.13 Disorientation 0.69 Stomach Awareness 0.06

Table 6.4.3 Comparison between two groups.

Group with previous MS Group without previous MS General Discomfort 0.56 General Discomfort 0.44 Nausea 0.38 Nausea 0.35 Headache 0.5 Headache 0.13 Disorientation 1.06 Disorientation 0.69 Stomach Awareness 0.38 Stomach Awareness 0.06

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Chart 6.4.4 Data representation of the compared data sets

Comparison between the groups with and without previous MS 1,2 1,06 1

0,8 0,69 0,56 0,6 0,5 0,44 0,38 0,38 0,4 0,35

AVERAGE SEVERITY SEVERITY SCORE AVERAGE 0,2 0,13 0,06 0 General discomfort Nausea Headache Disorientation Stomach awareness MOTION SICKNESS SYMPTOMS

Group with previous MS Group without previous MS

Fig. 6.4.4 is showing a clear overview of the average values of each VR sickness symptoms of both Group with previous MS and Group without previous MS. Both male and female participants are included in these set of processed data.

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6.5 The comparison between Male and Female groups Table 6.5.1 Average severity values for Male group.

Male General Discomfort 0.25 Nausea 0.13 Headache 0.23 Disorientation 0.38 Stomach Awareness 0

Table 6.5.2 Average severity values for Female group.

Female General Discomfort 0.25 Nausea 0.13 Headache 0.23 Disorientation 0.38 Stomach Awareness 0

Table 6.5.3 Comparison between Male group and Female group.

Male Female General Discomfort 0.25 General Discomfort 0.75 Nausea 0.13 Nausea 0.19 Headache 0.23 Headache 0.5 Disorientation 0.38 Disorientation 0.25 Stomach Awareness 0 Stomach Awareness 0.94

Chart 6.5.4 Data representation of the compared data sets

Comparison between male and female groups 1,2

1 0,94

0,8 0,75

0,6 0,5 0,38 0,4 0,25 0,23 0,25 0,19

0,2 0,13 SYMPTOM SEVERITY SCORE SEVERITY SYMPTOM 0 0 General discomfort Nausea Headache Disorientation Stomach awareness MOTION SICKNESS SYMPTOMS

Male Female

Fig. 6.5.4 is showing a clear overview of the average values of each VR sickness symptoms of both Male group and Female group. Both participants with and without previous motion sickness experiences are included in this set of processed data.

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6.6 Comparison of average values of overall VR sickness symptom scores Table 6.6.1 The average values of table, 6.1.2, 6.1.5, 6.2.2 and 6.2.5 are calculated and presented here. (Excluding the symptom of boredom)

Average values Male Female Group with previous MS 0.375 0.7 Group without previous MS 0.375 0.29 Average value for Group with previous MS: 0.54 Average value for Male Group: 0.375 Average value for Group without previous MS: 0.33 Average value for Female Group: 0.495 Chart 6.6.2 Comparison between Group with previous MS and Group without previous MS Overall comparison between the male and female groups

0,6 0,54 0,5

0,4 0,33 0,3

0,2

0,1

0 AVERAGE SYMPTOM SCORE SEVERITY AVERAGE Group with previous MS Group without previous MS COMPARISON GROUPS

Chart 6.6.3 Comparison between Male group and Female group. Overall comparison between the groups with and without previous MS 0,6 0,495 0,5 0,375 0,4

0,3

0,2

0,1

0

AVERAGE SYMPTOM SCORE SEVERITY AVERAGE Male Female COMPARISON GROUPS

Chart 6.6.2 and 6.6.3 Comparing the average values of the overall VR sickness symptom scores between two groups. Between group A and B, where group are the participants who have had previous motion sickness experiences and group B are the participants who have not had any previous motion sickness experience. The comparison was also done between the male and female groups; this will also provide a clue of if women are more vulnerable to Virtual environments or not. The statistical test Mann-Whitney U test will be used for finding significant values in this study.

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6.7 Qualitative results Due tremendous amount of collected data, the raw qualitative data from the individual interviews will not be included in this section, but instead of that the answers of each participant will be sorted and clustered in different groups in order to find something in common. (The original interview questions and qualitative questionnaires can be found in Appendix D and E) In the qualitative data analysis part, not all of the collected data were processed. And there were 10 randomly selected interviews with the test participants were processed and used for data analysis. The main reason of the interviews were randomly selected was because From the interviews I have successfully identified five categories of sorted answers that were shown repetitively in the interviews.

Qualitative results

Responsive

Easy to learn

Prefer motion controller

Natural movement CATEGORIZEDANSWERS

Fun & Immersive

0 1 2 3 4 5 6 7 8 9 10 PEOPLE WHO HAVE AGREED TO THE MATTER OUT OF 10

Fig. 6.7.1 Categorized & Sorted answers of the selected interviews answers and amount participant who have agreed to the matter. All of the answers from the individual interviews shares three common answers. All of the selected participants suggested that the Vive motion controllers were fun to use, and it also felt really immersive and realistic. All of the selected interviews of the test participants also reported that the controllers supported natural body movements, which they refer to using their body movements for in-game interactions. And they also suggested that they would prefer motion controllers even if they had to play a game for a very long time. At last, nearly half of them also claimed that the controllers were responsive and easy to learn. As the interviews have suggested, it was both fun and immersive to use motion controllers for VR games. This is phenomenon is also supported by the literature. In P. Cairns et al’s study of “The Influence of Controllers on Immersion in Mobile Games” suggested that using a motion controller for mobile games have shown higher scores in cognitive involvement, emotional involvement, real world dissociation and controls. (P. Cairns et al 2014) Therefore in this case it is reasonable to see that the participant’s enjoyment and immersion level got boosted using the Vive’s motion controllers. As the fig. 6.7.1 have shown, 10/10 of the randomly selected interviews of the test participants claimed that the Vive’s motion controllers supports a natural movement. By natural movement, they meant that some of the in-game interactions and controls is just like what we would do in the real life. A typical example of this is when some of the participants have encountered a trap inside the game.

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The trap is consisted of a few swinging blades that’s hanging from the ceiling of the in-game environment, in order to pass by this trap and collect the treasure on the way, players would have to go down to the floor as low as possible to avoid the blades. Others than that, there were several of the participants who claimed that the items were really easy to use because they were supported by motion controls. For instance, to attack or parry, the participants only needed to swing their arm or raise their arms naturally to perform a corresponding action. On the other hand, when players are using a , this is will be then normally done by pressing two different buttons. And compared to pressing buttons that explained exactly why it would feel more natural or more immersive to use a pair of motion controllers instead. According to the interviews in general, there has been a few people discussed the problem regard the design of the controller. Generally speaking, they were satisfied about the Vive controllers as they are today. But however, there were a few people who have complained about the discomfort of holding the controllers and the controllers were either too heavy or too light weighted for them. According to the interview with one of the participants, he suggested that the controllers felt really cheap and light weighted, during the experiment he was afraid of that he might break the controller in pieces if he hit something in the experiment location. On the other hand, one of the female participants has complained that the controllers were too big for her hands and a bit too heavy as well. She suggested that it should be designed in a way that it should be suitable for long term use, for instance longer than 30 minutes. There are a few more who have suggested about similar things during the interviews. This actually suggested how the controllers can be improved, one of the possibility is that to add customization elements on the controllers to make it lighter or heavier depending on the user. And it could also be customized in a way so that the controllers can be used in different genres of games as well.

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7. Discussion Sensory conflict movements is most likely to cause motion sickness (MS) and simulator sickness (SS) in VE as mentioned in the theory section. In this study only a small amount of sensory conflict movements were involved. This is mainly because of the hardware and corresponding content were selected in a careful way. Which means that the most recent released hardware and a game which didn’t involve that much sensory conflict movements were selected for this study. This was also done due to the ethical consideration of this study. And of course, the purpose of this experiment was not about making people to feel really sick, so the selection were made like that to avoid as much motion sickness as possible. Therefore it should be expected that a minimum of VR sickness or MS severity could be shown in the final result of this study. By strictly controlling the variables (Participants, equipment, content) of this study have certainly minimized the risk for the participants to experience extreme discomfort during the experiment. This was actually planned like this from the beginning, mainly because of the ethical consideration. However, this could also have made a huge impact on the results of this study, but at the same time the results would still be interesting and it will also put the modern VR equipment and content to a test. Which means that if people will still experience extreme discomfort under such controlled conditions in my study, then it probably indicates that the VR technology will never be able to get adopted by mainstream and mass-market. The result has shown that there is minimum amount of differences in virtual environment vulnerability between the participants who with previous motion sickness experience and the participant without such experiences. From chart 6.6.2, we can see that Group with previous motion sickness experience have an average score of 0.54 in overall virtual reality sickness symptoms, while Group without previous motions sickness have an average score of 0.33. It is important to mention here that the virtual reality sickness symptom severity scale is rated from 0 to 4, where 4 is the most severe level. In conclusion, the results have shown that the reported level of VR sickness severeness was small and the differences between genders and previous MS experiences was insignificant. 7.1 Significant difference According to the statistical test in the Appendix H and I, the Mann-Whitney U test results have shown that there are no significant differences between both groups of, and between Male and female groups. This was not surprising because the average values of the overall VR sickness symptoms was really low and the differences shown in the charts were also seemed to be insignificant. However, there were a few interesting points that’s worth to be mentioned here. From the chart 6.5.4 we can see that there are some major differences between the male and the female participants in VR sickness symptoms in general discomfort, headache and stomach awareness. What especially was interesting in this case was that none of male’s participants have reported any symptoms of stomach awareness while 5 of the female participant who have reported that they have been experiencing different levels of stomach discomfort. This could probably be explained by the works by G. Park et al, and R. S. Kennedy et al (1983) and (1985). In their work they have concluded that women were more vulnerable to virtual environments in terms of MS and SS compared to men. And R. S. Kennedy et al explained that the possible reasons might be the physiological, hormonal differences and the differences in FOV. 7.2 Detailed explanation of collected scores Another possible explanation of why the VR sickness symptom scores were so low can also depend on how the game used in this study was designed. According to Reasons Sensory conflict theory (1978) and Johnsons (2005), they have suggested that by decreasing mismatch of vestibular system may cause less MS or SS. The game used in this study “Vanishing Realms: Rite of steel” was exactly designed according to that. That means everything that player’s do in the physical world they does

38 match with the virtual world as well. They have also implemented a special way of moving inside the game to decrease the likelihood of VR sickness. Which is using the teleporting option instead of continues movements. In this sense player’s sensory system will not be mismatched and that reduced the risk of experiencing VR sickness for them. For example. If they have used a continues movement physics in the game, (moving forward when a button is pressed) then the character will be then moving forward in the virtual environment, this will then create a mismatch between our visual sensory system (our eye) and the vestibular system, where the brain tells you that you are moving forward but your body can’t actually feel it. In this sense, The games has provided a great example how other VR games should be designed and developed in terms of avoiding VR sickness. 7.3 Suggestions for the current MS measurement standard This study has also shown some suggestions for the current framework for analyzing MS or VR sickness. As my pre-study results have shown, the version of SSQ (Simulator Sickness Questionnaire) created in 1990s isn’t in its best shape today. For the common people or the consumers of VR products, it is probably the time to create a new framework that support the measurement of VR sickness. A few possibilities could be a new version of SSQ or even development of a new VRSQ (Virtual Reality Sickness Questionnaire) This technology is fairly recent and I think by using frameworks from almost 30 years ago is not quite enough anymore. The modern medical instruments may also help to accurately measure a user’s VR sickness experience, which may refer to measurements of body temperate, brainwaves, heartrates even GSR. (Galvanic Skin Response) 7.4 The process of sensorimotor adaptation From the qualitative interviews, I have also learned that approximately 1/3 of the participants have gone through a process of sensorimotor adaptation. As I have mentioned, by the time the study was carried out, the equipment used in this study was not more than 2 months old. That means the most part of the individuals have not had the chance to try out this device, in other words this device will be something that’s completely new for them. Therefore it is expected to see some of the participants to go through a sensorimotor adaptation process. Some participants reported that they were experiencing a slight dizziness and discomfort in the very beginning of the experiment through the think aloud method used in the test. However, none of them said that the discomfort persisted after spending a while inside the virtual environment. When I asked them how they felts after 15minute in to the test, they claimed that they feel much better and none of the VR sickness symptoms were present anymore. This phenomenon does match completely with M. A. Webster’s (2012) framework of sensorimotor adaptation. 7.5 Motion controllers for VR content From the interviews I have also learned that almost all of the participants would prefer using motions controllers to play a game, especially VR games. They have also claimed that they would stick to using motion controllers even if they had to play a game for 4 hours of time, which would require a lot of physical efforts. However, this has not been proofed by any studies or tests that they would do, so it is basically just an assumption from them. From this we can learn that this recently released VR device would attract a lot of users, mainly because of it would provide them with a brand new experience and more immersive moments. But to either use or not using motion controllers depends all on the games. In the interviews, most of the participants reported that playing games using motions controllers is a brand new healthy way of having fun. That is mainly because of it would require a lot of physical efforts to play. And even some of the participants who doesn’t really like to play video games have also suggested that they would like to play VR games, because it is completely different from the traditional screen based video games. Not all of the games are suitable for VR or motion controllers according to the interviews. Most of the participants suggested that they would use the motion controllers in long term as long as the game is well designed and attractive. So this actually suggested that people would not become bored or tired

39 of using motion controllers just because they would require more physical efforts than traditional controllers such as gamepads, mouse and keyboard. It always depends on the content of the platform. As previous studies have suggested that there are always some games fits well together with the VR technology, but not all. This has been also confirmed by a previous study done by a Bachelor student in Uppsala University Campus Gotland, where he concluded that not every game fits well with the VR technology (L. Augustsson 2015) 7.6 Limitations There has been a minimum amount of limitations discovered in this study. Mainly because I have carried out similar controlled studies before during my Bachelor degree, I was aware of that how outdated hardware and individual differences can affect the reliability of the test results. I have been keeping these limitations in mind since the very beginning of this study, and I have done my best to overcome and avoid these limitations. Such as the equipment used in this study is the most modern and up to date devices, and every single participants is carefully selected. However, there are still some individual differences between that participants that I could not control which was the gamming experiences of recruited participants. They have a fairly distributed experiences in terms of gameplay in video and computer games. (See fig. 5.3.2) Some of the participants claimed that they were not interested in games at all, and it would be hard for them to imagine how the experiences would be like if they for instance need use motion controllers to play a game for 4 hours of time. Another limitation was the experiment location. Since the study was carried out in a private apartment, there were a lot of obstacles and very limited amount of space available. That would easily make the test participants bump into different objects in the experiment location. Many of the participants suggested that their movements felt restrained because of they were afraid of bumping in or hitting random objects in the experiment location. Cord and cable problem has also been one of the limitations for this study, 90% of the participants claimed that sometime during the test they have been bothered by the cables that is connecting the Vive headset and the PC, they reported that they got tripped by the wires and that has a huge impact on the maintaining the immersion and the sense of flow. 7.7 Recommendations for future work My study has probably made a tiny contribution to the field and industry, therefore more similar studies need to be carried out in order to find more leads. In this case I would recommend other researchers or students to look more in the details of similar studies. Maybe try to find out more about how does usage time have an impact on user’s virtual reality sickness experience? Or if there are different types of motions inside the VE or VR games that have a higher chance of inducing VR sickness? And also a long term study would even bring more insights and evidences of user’s real feelings toward the use of motion controllers. Another recommendation would be that carry out the similar studies in an empty and professional facility. Which may provide a massive amount of play area for the participants without having them worried about bumping in to objects. This would help to take their immersive experience further to the next level.

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8. Conclusions The results of this study indicated that the people who have had previous motion sickness experiences tend to suffer a bit more from VR sickness, see chart 6.6.2. However, the reported level of VR sickness symptom severeness were small and the differences between the two groups with different previous motion sickness experiences were insignificant as well, according to the statistical calculation. (Appendix H) The results have also indicated that female participants were more vulnerable to VR or VE, just like the previous literatures have shown. The female group have shown a higher level of symptom severeness compared to the male group, especially in stomach awareness, see chart 6.5.4. However, again the differences between the gender groups were insignificant as well according to the statistical test. (Appendix I) The previous literature also indicated that there are individual differences when it comes to VE in terms of MS or VR sicknesses. One of the aspects were gender difference, and in G. park et al and R. S. Kennedy et al’s studies, they have both claimed that women are more vulnerable to virtual environments in terms of MS and SS. The results of this study have shown that the female participants reported a higher level of symptom severeness but the differences were insignificant compared to the male participants. This could be possibly explained by the equipment used in this study was well optimized for the users and mass market. If another set of equipment with less advanced positional and motion tracking technology were used in this study, the result might turn out to be very different. That could also be depended on how the corresponding VR content is designed, if the design principles are against the basic framework of sensory conflict theory then there will still be a higher risk of experiencing VR sickness for some of the individuals. In this case, it is acceptable to claim that “PCVR equipment with advanced positional and motion tracking technology together with well- designed VR content is universally accessible and fit for most of the users.” At this point the research question of this study has been clearly answered. The aim of this study was about finding out if there are any universal accessibility issues with recently released VR technologies. The results of this study have indicated that there are NO obvious universal accessibility issues with HTC VIVE. Because both small symptom severeness and insignificant differences between different participants group were shown in the result of this study. It has indicated that this set of equipment could be really well optimized for the consumer market. This conclusion could be generalized to any recently released VR products that comes with such accurate positional and motion tracking system, which will limit to the PCVR type of equipment. The mobileVR and standaloneVR devices comes with less advanced positional and motion tracking technology, which means that using those types of VR products will be a complete different experience, compared to PCVR products. According to the results of pre-study, it is also possible to conclude that the old framework of measuring MS and SS is sort of not eligible anymore, we need immediate update on the framework and develop new and more modern ways of accurately measuring not only MS and SS but also VR sickness. According to the qualitative results of this study, it suggested that using motion controllers together with VR technology is a good and captivating experience. People would not stop using motions controllers after a long term of use, as long as the VR content is designed according to the hardware, then users will always be attracted to use VR devices and motion controllers. The results have also shown that most of the people think that it is more fun and immersive to use motion controllers in RPG games rather than gamepad and other control mechanisms. It has also suggested that the current version of Vive motion controllers are well designed, and most of the people are satisfied and happy with its current form. But however, the qualitative results of this study has also indicated that allowing customizations on the motion controller would improve the user experience for a certain group of people.

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In a nutshell, this study have tested two conditions (people with previous motion sickness experience and female users) which might cause an impact on the accessibility of VR. This study have indicated that current PCVR with advanced positional and motion tracking technology do not have any universal accessibility issue. However, more conditions and factors are needed to be identified and tested in order to explore further into the problem. A recommendation for future studies would be carrying out similar studies using different types of VR devices, such as MobileVR and StandaloneVR devices. Combining results from these studies, a stronger overall conclusion can then be drawn. And in that sense problems related to overall VR universal accessibility will be even more revealed and explored. My positive attitude toward the modern VR technologies probably have also affected the results of this study. However, the use of a controlled experiment setup should have minimized this factor. This study may also imply that the current VR technology is developing on the right track and this time the technology is well optimized for the consumer market, which could mean that the year of 2016 could really be the start of the era of Virtual Reality.

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10. Appendices Appendix A Consent form:

Objective:

The purpose of this document is to obtain your consent to record today’s testing sessions. Today’s session will be recorded for deeper analysis, and the recorded material will only be used internally within the study and academics and it will not be used or published for any other purposes.

Consent:

I agree to participate in the study conducted by Dong sheng Lu, Master student of Human Computer Interaction, Department of Informatics and Media, Uppsala University.

I understand that participation in this study is voluntary and I’m aware of that this study may cause different degrees of discomfort. I’m also aware of that I have the freedom to withdraw anytime during the experiment and have the right to raise any concerns to the experimenter.

Any personal information and collected data will stay confidential and be used for academic purposes. Please sign below to indicate that you have read and understood the information on this form and that any questions you might have about the session have been answered.

Date: ______

Participant’s signature: ______

Thank you for your participation!

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Appendix B

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For the online version: http://goo.gl/forms/W5fC6Q0AOI

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Appendix C

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For the online version: http://goo.gl/forms/RRGKqmniN5

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Appendix D Interview questions regarding Vive’s motion controllers:

1. How would you describe your experiences with these (Vive’s) motion controller? 2. Which other game controllers have you used before? How do you think these motion controllers differs from those control options? 3. How would you describe the experience if you used an Xbox/ PS controllers instead of the motion controllers? How would it be different? 4. Which type of games do you think are most fitted to this controller? 5. What are the advantages and disadvantages with these motion controllers that you have tested? 6. What would you think if you used these motion controllers to play video games on Xbox, PS and PC instead of the other controllers, keyboards and mice? 7. How would you feel if you used these controllers to play games every day during several months or years of time? 8. If you had the chance to choose between sitting down and use a hand controller and standing up and using motion controllers to play a same game during 4 hours, which option would you choose? And why? 9. How do you think the controllers can be better designed to achieve a higher comfort and satisfaction rate?

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Appendix E Qualitative questionnaire:

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For the online version: http://goo.gl/forms/mZvV4UKTm6ZtI03E3

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Appendix F Raw data collected from Qualitative questionnaire

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Appendix G Mann-Whitney U Test Table of critical values. Alpha = 0.05 (Two tailed)

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Appendix H Mann-Whitney U Test for finding significant difference between Group with and without previous motion sickness experiences.

Ranked order Ranked order Group A 푅1 Rank Group B 푅2 Rank 0 0 5 1 0 5 0 0 5 0 0 5 1,2 0 5 0,6 0 5 0,6 0,2 12,5 0 0 5 0,2 0,2 12,5 0 0 5 0,2 0,2 12,5 0,4 0 5 0 0,2 12,5 0,4 0,2 12,5 0,8 0,6 21,5 0 0,2 12,5 0,2 0,6 21,5 0 0,4 17,5 0,6 0,6 21,5 0,8 0,4 17,5 1,6 0,8 24,5 0,4 0,4 17,5 0,2 1 27,5 1,4 0,4 17,5 1 1 27,5 0,2 0,6 21,5 1 1 27,5 0,4 0,8 24,5 0,6 1,2 30 0,2 1 27,5 1 1,6 32 0 1,4 31

Σ푅1 Σ푅2 298,5 229,5 Formula for calculating 푈1 and 푈2 ퟏ 푼 = (푵 × 푵 ) + ( × 푵 ) × (푵 + ퟏ) − 푹 ퟏ ퟏ ퟐ ퟐ ퟐ ퟏ ퟐ ퟏ 푼 = (푵 × 푵 ) + ( × 푵 ) × (푵 + ퟏ) − 푹 ퟐ ퟐ ퟏ ퟐ ퟏ ퟐ ퟏ ퟏ 푼 = (ퟏퟔ × ퟏퟔ) + ( × ퟏퟔ) × (ퟏퟔ + ퟏ) − ퟐퟐퟗ. ퟓ ퟏ ퟐ

푼ퟏ = ퟏퟔퟐ. ퟓ

ퟏ 푼 = (ퟏퟔ × ퟏퟔ) + ( × ퟏퟔ) × (ퟏퟔ + ퟏ) − ퟐퟗퟖ. ퟓ ퟐ ퟐ

푼ퟐ = ퟗퟑ. ퟓ According to the critical value table in Appendix G:

The critical value is 75 at significance level of 5%

Using the lower value of 푼ퟏ 풂풏풅 푼ퟐ 93.5 >75 Hence there is no significant difference.

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Appendix I Mann-Whitney U Test for finding significant difference between Male group and Female group

Male Ranked order Rank Female Ranked order Rank 0 0 5 0,2 0 5 0 0 5 0,6 0 5 1,2 0 5 1,6 0,2 12,5 0,6 0 5 0,2 0,2 12,5 0,2 0 5 1 0,2 12,5 0,2 0 5 1 0,2 12,5 0 0 5 0,6 0,4 17,5 0,8 0,2 12,5 1 0,4 17,5 1 0,2 12,5 0 0,6 21,5 0 0,4 17,5 0,8 0,6 21,5 0,6 0,4 17,5 0,4 0,8 24,5 0 0,6 21,5 1,4 1 27,5 0 0,6 21,5 0,2 1 27,5 0,4 0,8 24,5 0,4 1 27,5 0,4 1 27,5 0,2 1,4 30 0 1,2 29 0 1,6 31

Σ푅1 Σ푅2 219 306 Formula for calculating 푈1 and 푈2 ퟏ 푼 = (푵 × 푵 ) + ( × 푵 ) × (푵 + ퟏ) − 푹 ퟏ ퟏ ퟐ ퟐ ퟐ ퟏ ퟐ ퟏ 푼 = (푵 × 푵 ) + ( × 푵 ) × (푵 + ퟏ) − 푹 ퟐ ퟐ ퟏ ퟐ ퟏ ퟐ ퟏ

ퟏ 푼 = (ퟏퟔ × ퟏퟔ) + ( × ퟏퟔ) × (ퟏퟔ + ퟏ) − ퟑퟎퟔ ퟏ ퟐ

푼ퟏ = ퟖퟔ

ퟏ 푼 = (ퟏퟔ × ퟏퟔ) + ( × ퟏퟔ) × (ퟏퟔ + ퟏ) − ퟐퟏퟗ ퟐ ퟐ

푼ퟐ = ퟏퟕퟑ According to the critical value table in Appendix G:

The critical value is 75 at significance level of 5%

Using the lower value of 푼ퟏ 풂풏풅 푼ퟐ 86 >75 Hence there is no significant difference.

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