Nausea, the great evil of virtual reality
Virtual reality headsets sometimes cause unwanted effects to their users. A risk that the industry and game publishers must take into account.
The future can sometimes make you want to vomit. In recent months, several virtual reality headsets have arrived on the market, such as the Oculus Rift (owned by Facebook), the HTC Vive or the PlayStation VR. The opportunity for players to discover a promising new technology, but also to confront a problem of which they have not necessarily been warned: the painful side effects of virtual reality
For many people, the experience of virtual reality headsets comes at the cost of more or less painful side effects. Dry eyes, headache, and, most importantly, strong nausea. This last symptom is the one that worries users the most, to the point of having its own Wikipedia page under the name of “virtual reality sickness” or “cybersickness”. Even the CEO of Oculus, the company that develops the pioneering headset in the sector, complained about the problem during the first tests of the Oculus Rift. “Every time I put on the helmet, it makes me sick,” Brendan Iribe admitted in 2013.
Three years later, the disease is still rampant. “This is a problem that always comes up when we study the side effects of virtual reality,” confirms Eloi Duclercq, who carried out a study on the subject on behalf of the consulting firm LudoTIC. Those affected describe symptoms similar to motion sickness, also called motion sickness: nausea, cold sweats, heavy breathing. Enough to spoil the gaming experience. Even, for the most pessimistic, to jeopardize the success of this technology, which must be one of the great successes of Christmas.
A common but unknown disorder
Like motion sickness, virtual reality nausea does not affect all people the same way. Some do not feel any symptoms of discomfort. Others are unable to play more than five minutes. The urge to vomit and headaches can occur at the time of play, when removing the headphones or after the session. The French publisher Ubisoft conducted a study about 400 players confronted with virtual reality: more than 45% of them declared themselves sensitive to motion sickness, and 6% as being “very sensitive”, according to the results unveiled at the #GamesUR conference, held in September in London.
“The visual system not only serves to see, but also to stabilize us in space “
Philippe Fuchs, professor at Mines ParisTech
“There are very few reliable studies on motion sickness, while it is a common evil,” says Philippe Fuchs, professor at Mines ParisTech and author of the book Les casques de réalité virtuelle et de jeux vidéo (édition des Mines). In his book, one of the few on the subject, he lists eleven “disruptive inconsistencies” that can involve discomfort or discomfort in virtual reality users. So not all of them cause nausea. The most important is the visuo-vestibular inconsistency, that is, between vision and the vestibular system, the organ of balance. The user sees movement while his body remains in a static state. The brain is disturbed and eventually sends alarm signals, in the form of nausea. The sensation is similar to that experienced by a sick person in a car.
There are other, less well-known inconsistencies, but they can be just as disruptive to VR users. Too much latency between head movements and the display of images on the headset can be a big source of discomfort. Another problem, too low an image display frequency (fps, for frames per second) can contribute to making you sick. “The visual system serves not only to see, but also to stabilize us in space,” explains Philippe Fuchs. “The higher this frequency, the smoother the movements seem to us.»
The evil of virtual reality is not inevitable. Several tricks are already known to researchers and industry to reduce the feeling of nausea, and therefore facilitate the experience of players. First there are the technical solutions, which headphone manufacturers and game publishers must take into account: we know that we must limit the lag time between head movements and images displayed to less than 20 milliseconds, otherwise we will feel uncomfortable. The frame rate should be at least 60 fps. Some headsets, such as the HTC Vive or Oculus Rift, even impose frequencies of at least 90 fps.
Other solutions are more creative. It is thus not recommended for game creators to show too erratic acceleration movements or make too sharp turns. “The problem with turning around in virtual reality is that you can’t really turn your head to go with it,” explains Duclercq. In his study, the latter established a correlation between the feeling of nausea and eye movements. The shorter the fixation of the gaze, the sicker the user. “You have to limit the information on a screen, otherwise the gaze no longer knows where to attach itself,” he explains. Eloi Duclerq recommends to prefer the displacement “by boxes” rather than in linear trajectory. This amounts to a kind of teleportation, in which the player moves from one point to another, without moving, and therefore disturbing his brain less.
In addition to limiting movement, it is also a matter of giving stable marks to the player. In a car game or using another mode of transport, it is advisable to leave a dashboard visible. “Having a reference to the real world is crucial,” says Philippe Fuchs. “When we play a racing game on a computer, we are not sick, because our peripheral vision detects what is happening outside the game, which is our computer and a stable world. The false cockpit makes it possible to recall this stability.”This principle can give far-fetched applications: an American researcher from Purdue University believed that it was possible to reduce nausea by adding a virtual nose in the game.
Experiments should be developed with caution by publishers, so as not to make their players sick, and potentially disgust them with their work. The first games available in the early days of virtual reality rarely took into account these poorly known parameters. Today, as headsets begin to be available to the general public, developers are better informed. “We don’t want players to start saying: I don’t like virtual reality because it makes me sick!”warned Laura Glibert, researcher at Ubisoft, at the #GamesUR conference.
“We don’t want players to start saying: I don’t like virtual reality because it makes me sick.”
Laura Glibert, Ubisoft
Ubisoft took several months to develop its game Eagle Flight, by having it pass a battery of tests with testers and compiling scientific research on the subject. The game, which allows to embody an eagle, thus offers several visual landmarks: the false nose imagined by Purdue University becomes here a beak in pixels. Many games also borrow the principle of teleportation recommended by researchers, such as the virtual reality version of Fallout 4 or Robo Recall, developed for the Oculus Rift. But others are still very poorly optimized, including from very large studios, who rush to virtual reality without taking the necessary precautions. The virtual reality version of the seventh installment of Resident Evil sickened several journalists who came to try it out at E3, the big annual video game show, in June. Capcom, which is developing the game, put the controversy into perspective by saying that the specialized press was not yet “accustomed enough” to virtual reality. “The development for virtual reality does not look like the classic game development”, had reacted John Nagle, independent developer, in a text widely relayed on social networks. “You can’t just put a virtual reality camera in your scene, and hope everything goes well. (…) Your players will hate their experience. And because you are a great developer, they will assume that this is the best that virtual reality can offer them. The whole industry will suffer.»
This reputation issue is also valid for helmet manufacturers, for whom a poorly adapted game can weigh on their image. The release of Sony’s PlayStation VR was met with several articles complaining about discomfort issues. The fault is a selection of early games available with too many works at risk, that is, potentially causing nausea. The American site IGN even published an article ranking all games according to their “nausea potential”. Not necessarily enough to motivate a player to spend several hundred dollars in a helmet. The virtual reality industry is still expected to generate $ 1 billion in revenue in 2016, according to Deloitte estimates.