Human Factors in VR

1. Electrical and Computer Engineering Dept. Human Factors in VR

2. User (programmer, trainee, etc.) System architecture

3. Human Performance Efficiency Health and Safety Societal Implications Human factors in VR (Stanney et al., 1998)

4. Human factors in VR Will the user get sick in VR? How should VR technology be improved to better meet the user’s needs? ? Which tasks are most suitable for users in VR? How much feedback from VR can the user process? Which user characteristics will influence VR performance? Will the user perceive system limitations? Will there be negative societal impact from user’s misuse of the technology? What kind of designs will enhance user’s performance in VR? (Stanney et al., 1998)

5. Health and Safety Human factors in VR Human Performance Efficiency Societal Implications (Stanney et al., 1998)

6. Effects of VR Simulations on users The effects VR simulations have on users can be classified as direct and indirect; Definitions Direct effects involve energy transfer at the tissue level and are potentially hazardous; Indirect effects are neurological, psychological, sociological,or cybersickness and affect the user at a higher functional level.

7. Direct Effects of VR Simulations on Users • Affect mainly the user’s visual system, but also the auditory, skin and musculoskeletal systems; • Effects on the skin and muscles are due to haptic feedback at too high a level.

8. But users and their surroundings get injured • The intensity of the game playing can lead to injury. Statistics posted on www.wiihaveaproblem.com/damage.phphttp://show 41 people, 25 TVs, 19 lamps, 9 ceiling fans, 6 pets. etc http://www.kctv5.com/health/14978010/detail.html

9. Direct Effects of VR Simulations on Users • Effects on the visual system occur when the user is subjected to high-intensity lights directed at his eyes (like Lasers used in retinal displays (if they malfunction), or IR LEDs as part of eye tracking systems; • An “absence” state can be induced in a user subjected to pulsing lights at low frequency (1-10 Hz); • Bright lights coupled with loud pulsing sounds can induce migraines (20% of women and 10% of men are prone to migraines. • Direct effects on the auditory system are due to simulation noise that has too high a level (115 dB after more than 15 minutes);

10. Cyber sickness • User safety concerns relate primarily to cyber sickness, but also to body harm when haptic feedback is provided; • Cyber sickness is a form of motion sickness present when users interact with virtual environments; • Cyber sickness has three forms: • Nausea and (in severe cases) vomiting; • Eye strain (Oculomotor disturbances); • Disorientation, postural instability (ataxia) and vertigo. • Flight simulators have an incidence of up to 60% of users experiencing simulation sickness (military pilots – elite group); • Studies suggest regular VR users are affected more (up to 95%) (Stanney and Hash, 1998)

11. System characteristics influencing cyber sickness • When VR technology has problems, it can induce simulation sickness. Example: • Tracker errors that induce a miss-match between user motion and avatar motion in VR; • System lag that produces large time delays between user motion and simulation (graphics) response. Lag is in turn influenced by tracking sampling speed, computer power, communication speed, and software optimization. • HMD image resolution and field of view. Poor resolution and small FOV are not acceptable. Large FOVs can also be problematic.

12. Influence of user’s characteristics on cyber sickness • The user characteristics can play an important role in cyber sickness: • Age that induce a miss-match between user motion and avatar motion in VR; • Health status. Sick users, including those that take medication or drugs are more prone to cyber sickness. • Pregnancy. Female users who are pregnant are more prone to simulation sickness. • Susceptibility to motion sickness. Some people are more prone to motion sickness than others. Pilots are screened for such.

13. Influence of user’s degree of interactivity on cyber sickness • HF studies done at University of Central Florida (Stanney and Hash, 1998) to determine influence of user degree of control on cyber sickness in VR; • Task was 3-D navigation in a maze (shown below): 3-D navigation task (Stanney and Hash, 1988)

14. Influence of user’s degree of interactivity on cyber sickness • There were three control conditions: • Passive control – users were “taken on a ride” on a preprogrammed path, and had no input to the simulation; • Active control – users navigated using a joystick with 6 DOF; • Combined active-passive control – users navigated using the same joystick, but with some degrees of freedom disabled, based on task-specific motions (doors, windows, elevators); • There were eight subjects in each experimental group (24 total, both male and female); They each performed the task for 30 minutes; • The virtual environment was displayed on a PC in stereo, so subjects wore stereo glasses. • Results showed that active-passive control reduced significantly cyber sickness effects. Passive control did worse. 3-D navigation task (Stanney and Hash, 1988)

15. Passive Control Active Control SSQ Score Active-Passive Control Nausea Oculomotor distortion Disorientation Total severity Influence of user’s degree of interactivity on cyber sickness • Active-passive control is better than active control, because unnecessary motions are eliminated, thus reducing the amount of neural conflicts. Both reduce adaptation time. • Simulation sickness was self-reported by subjects using a Simulation Sickness Questionnaire (SSQ) 3-D navigation statistics (Stanney and Hash, 1988)

16. Neural Conflict • Occurs when simulation and body sensorial feedbacks conflict; • The conflict (sensorial rearrangements) can be of three types: • Type I: two simultaneous conflicting signals (A and B) – example Information from a moving platform does not coincide with the motion of waves seen on an HMD. • Type II: Signal A is present and B is not – example looking at a roller coaster simulation, without a motion platform; • Type III: Signal B is present and signal A is not – flight simulation in fog (instrumented flight). Motion platform moves, but visual feedback is unchanged. • Since more information from the simulation results in more conflict, it is logical that neural conflict induced cyber sickness grows with the duration of immersion in the VE.

17. Influence of exposure duration on cyber sickness • HF studies done at University of Central Florida (Kennedy et al., 2000) to determine influence of simulation duration on cyber sickness; • Task was flying a helicopter, and subjects were military pilots; • The data was divided according to duration in: • Simulation session of 1 hour or less; • 1 to 2 hours; • 2 to 3 hours; • Simulation session of over three hours • It showed that there is a linear relationship between duration of simulation and the degree of simulation sickness; Thus the duration of initial exposure should be limited, to minimize discomfort;

18. Influence of simulation duration on cyber sickness Average Total Sickness Score (Kennedy et al., 2000) Flight Session Duration (in hours)

19. Influence of repeated exposure on cyber sickness • HF studies done at University of Central Florida (Kennedy et al., 2000) to determine influence of user adaptation on cyber sickness; • Since prior neural images play such an important role in cyber sickness, can repeated exposure to VR desensitize the user? • Study looked at military helicopter simulators, thus subjects were pilots, and task was prone to induce sickness (violent maneuvers). • The study used a “Total Simulation Score” with a 35% as zero-point. Thus for military pilots 35% incidence of simulator sickness is considered acceptable. For the general public it is not. • Results showed a significant reduction in TSS after a few flights showing that the subject had adapted to the neural mismatch. While mismatches exist, there are considered as matches due to prior experience.

20. Average Total Sickness Score Flight Number Influence of repeated exposure - results • The study did not indicate how long the subsequent exposures should be, nor over what time interval they should take place. It is believed that no more than one week should separate simulation sessions. Cyber sickness scores vs. number of successive flights (Kennedy et al., 2000)

21. Adaptation Definition “Adaptation to sensory rearrangement is a semi-permanent change of perception and/or perceptual-motor coordination that serves to reduce or eliminate a registered discrepancy between, or within, sensory modalities, or the errors in behavior induced by this discrepancy.”

22. Adaptation Hand-eye coordination adaptation: a) before VR exposure; b) initial mapping through artificial offset; c) adapted grasping; d) aftereffects. From Groen and Werkhoven [1998].

23. Aftereffects • Induced through adaptation to neural conflicts. • Occur after the simulation session ended and can last for hours or days; • While adaptation is good, aftereffects may be bad. Forms of aftereffects are: • Flashbacks; • Sensation of “self motion”; • Headache and head spinning; • Diminished (remapped) hand-eye coordination; • Vestibular disturbances; • These aftereffects lead Navy and Marines to institute grounding policies after simulator flights. Other bans may be necessary (example driving, biking, roof repair, operating machinery, etc.).

24. Guidelines for Proper VR Usage Meant to minimize the onset and severity of cybersickness. They are largely qualitative

25. Guidelines for Proper VR Usage

26. Human factors in VR Human Performance Efficiency Health and Safety Societal Implications (Stanney et al., 1998)

27. Social implications of VR • Violence of VR games are a concern, as additive response could result. Violence may also induce desensitization to real-world violence. This may be another negative “after-effect” of VR. • Another social impact may be increased individual isolation, through reduced societal direct interaction and involvement. Avatar-mediated interaction, while allowing sharing of virtual worlds may not be a substitute to direct human-human interaction. • Synthetic and distance learning using VR may not adequately replace direct student-professor interaction. Reduction in education quality may result; • Reduction in health-care quality may also be present – especially for mental health and at-home rehabilitation.

28. Social implications of VR Online societies such as theAlphaworld

29. Second Life Online Society http://secondlife.com People become members, then can build communities or islands, buy at virtual stores and play games. “An online 3D virtual world imagined and created by its Residents

30. Mental rehabilitation VR systems • One form of game-based mental training is the Nintendo DS and Nintendo DS Lite • It allows seniors to have fun while playing mind-challenging games, using a stylus and voice input • Brain Age 2 has100 activities designed to help work your brain and increase blood flow to the prefrontal cortex.

31. Mental rehabilitation VR systems • When starting a new game, you will take a series of tests that show how old your brain is (“Brain Age”). • With daily training over weeks and months, you can improve your mental acuity and lower your Brain Age. • Can compete against others

32. Online Cognitive Rehabilitation • The Lumosity Co. (lumosity.com) allows subscription ($10/month) to video games that train the attention, memory, cognitive control and processing speed with against-the-clock games. • After 30 sessions subjects that played the games also improved in independent tests of memory.

33. The dangers of video games (general) • Excessive game play can be fatal. In Korea, where 30% of the population subscribes to online multiplayer games, one man died in 2005 after playing 50 hours (almost non-stop) StarCraft. 3 Chinese died in 2007 after playing more than 50 hours, and 2 died in 2005. EverQuest is a 3D online game played by more than 400,000 people; Games can lead to isolation, and suicide. Hudson Wooley, an epileptic who was playing 12-hours per day, eventually committed suicide.