I think about motion sickness a lot these days. I used to have problems with it from time to time, but I have developed strategies to deal with it. Mind you I don't spend much time on boats or roller coasters, so technically the word that most people use for what used to happen to me and currently happens to my younger child is "carsick". My younger son has really liked playing Scribblenauts Unmasked lately, but he's had to be careful about how much he plays in the car.
I don't remember ever having big problems reading in the car on family vacations, but since we had a big van I was probably lying down when I was reading. I think it happened occasionally, but I couldn't nail down the triggers for it specifically. The first time I specifically remember having a big problem was after I got a Game Boy.
The first video game that made me sick was "Atomic Punk". It's not that it was a poorly Americanized attempt at re-branding Bomberman while capitalizing on the success of the Game Boy as a platform, although I can certainly see how you might think that. It's just that I was so nuts for Bomberman then that I wanted to play it all the time - especially on long road trips where all I really had to do was sit in the passenger seat and navigate. However, that was exactly the time that I could not play it. I was ready to hurl even before we got out of the city limits. It has occurred to me that the biggest difference between playing an action game and reading a book in terms of the motion sickness that when reading a book, there is nothing to stop you from periodically looking up from the book. (Sure, you could pause the game, but who does that?) So, when playing a game in the car, you're looking at a mostly fixed screen, and your peripheral vision is seeing the interior of the car which is also not moving, but your inner ear is reporting data that would indicate that you are moving. So, I presume that motion sickness stems from the brain's inability to process conflicting data under certain conditions.
Now, some people that I know used to get nauseous from playing first person shooters back in the early days, like playing Doom and Quake. This is kind of the opposite problem from the handheld game, where your peripheral vision and your inner ear report no movement, but your central vision reports movement. I do not recall ever having issues with this back then, but I started playing Doom and Quake with the arrow keys and I did not start whipping my point of view around with the mouse in a rapid fashion until some time after I started playing those games. Since how much you move around depends on your input to the game, I presume that I had no issue with it because I understood the relationship between controller input and screen movement.
Typically when moving around in a virtual world, or watching a movie where they pan the camera around, the motion is very smooth. Part of the reason it tends to be smooth in the game is because you're aiming the direction of movement and your weapon with the mouse, so it needs to be somewhat smooth so you can aim your weapon and travel in the intended direction. Your brain is able to extrapolate perceived movement and figure out where you are looking to some degree.
Once the camera becomes small enough that it can fit in a person's hand, all that smoothness is right out the window and we end up with feature films like The Blair Witch Project, which I thankfully watched in a nearly empty theater in the middle of the afternoon so only my wife and a friend of mine had to watch me slowly freak out. The movie was considered innovative for its use of handheld footage, but it was too jittery for me to process. I tried using chocolate and caffeine to combat the effects, but I left the film feeling like someone punched me in the back of the neck. This is similar to the Doom/Quake example where the inner ear and peripheral vision report no movement but central vision reports movement, but I wonder to what degree the brain trusts your peripheral vision in a movie theater.
I presume that this is similar to why some people have problems with in 3D films, again because of the differential between the inner ear information and the visual information, but complicated by the problems with stereo vision and a forced fixed perspective. When you move your head around in a 3D film, the 3D scene doesn't correctly track to your head movement, so again you have a disparity that your body's visual procession and sense of balance aren't happy about. I haven't had issue with this yet, but I have been pretty picky about which 3D movies that I've watched so far.
With games, I had assumed that since I hadn't had any issue with the old first person shooters, I was unlikely to have any issues with any games. Strangely, this turned out to be wrong. The first time I had a big problem with in-game nausea was the 2001 Playstation 2 game Twisted Metal:Black. It's not a first-person shooter, it's a related genre that only exists periodically: Vehicluar Combat. Despite imitators like Vigilante 8, Blood Drive, and Twisted Metal 3 and 4, Twisted Metal:Black reigns as the best of the genre and a good game in its own right. Running on a rather well-optimized engine and capable of a rather high sustained frame rate, there seemed to be too much going on. I was only able to play the game by building up a tolerance for it, and I think I still only managed to finish with some of the characters. I don't recall that the game was jittery, only that is was fast, so I don't feel like I sufficiently understand why the game made me motion sick.
Just recently, I have been making some progress on Resident Evil 6. This game is similar to Resident Evil 4 and 5 in presentation where the camera is positioned over your character's shoulder. I have tried to play the Mercenaries mode a lot to acclimate myself to the controls, and I have just gotten to the second chapter of Chris' campaign having started there after many attempts at the introduction. I have noticed that the game engine is rather sophisticated and tries to replicate a cinematic feel some of the time, including an area where you fight a boss enemy from the second floor of a building which he's trying to knock down while you're in it. What do you get when the boss is trying to knock down the building you're in? Jittery Action! I was so glad to get to a checkpoint so I could quit but I think I'm nearly out of bullets. So, if you hear me say that Resident Evil 6 makes me sick, it's not a comment on the story.
Well, at least not yet it isn't.