Playing an Xbox game, I jump off a high cliff or building and physically feel the weird elevator-like sensation, while I’m sitting motionless on my couch. What’s going on in my body/brain to cause this? Is it different from what causes it when you actually jump? Also, is there a name for it? Is it a type of vertigo?
It’s caused by mirror neurons Mirror neuron - Wikipedia
A useful application of mirror neurons is with phantom limb pain
The network of brain regions that deal with spatial orientation and feeling of motion (vestibular nuclei, vestibulo-cerebellum, thalamus) is well known. The vestibular system is known for provoking all sort of visceral sensations (elevator feeling, motion sickness, etc) but the underlying physiology is not understood.
If your visual display is immersive enough, the motion on the computer screen can feed into this network and create an illusion of self-motion (in this case it is called vection). This is a well understood phenomenon.
Other than that, this brain network may actually learn the physics of video games well enough to start recruiting these brain regions when you play computer games. I would speculate that being cognitively immersed in a game may actually drive neuronal activity in these regions (that would normally only be activated due to real motion or very immersive visual motion) and trigger these sensations.
I am not aware of brain studies on this topic though; that would be cool to do.
This must be similar to the well-known phenomenon observed when you are sitting in a stationary car in a parking lot, and the car next to you starts to pull out. You get the sensation that your car has started rolling the other way.
Similarly when you are sitting in a stationary train, and a train passed on an adjacent track.
Our instinctive fear of heights is basically tied to our vision. We’re hard-wired to be uncomfortable with a long focal distance looking down.
Then, knowing we’re near such a precipice, any further movement in that direction triggers a feeling of panic that makes us grab for whatever we can.
All this can happen while just viewing video games or films or whatever.
I suspect this is what is happening with the OP; it’s not so much the falling as it is the initial fall / leap, and the feeling that may persist for some seconds afterwards.
In a similar vein, motion sickness. Which is caused by your ears telling your brain “We are sitting, motionless” while your eyes tell it “we’re moving hella fast right now !”. I expect the falling sensation is similar - eyes telling the brain “we’re falling to our death !”, the rest of the body saying “uuuh… no we’re not ?” and the brain picking the more urgent/dangerous stimuli to respond to.
You want to know a really weird thing though ? In the Assassin’s Creed series, the character you’re playing keeps leaping down from high buildings onto hay carts - which results in a harmless landing, because screw Newton that’s why. And when I do that in the game, I don’t feel anything. It’s just a thing you repeatedly do in those games; , no biggie. However, when I misplay and end up jumping from a high roof to certain (in-game) death on the cobblestones below, I *do *feel that “falling to my doom” sensation.
Puzzle that out, brainiacs.
May I just point out that vertigo is nothing to do with a fear of heights or falling. It is a balance problem, usually caused by Ménière’s disease or labyrinthitis .
Fear of heights is called acrophobia.
So, basically, you’re saying that motion sickness could be stopped by shutting your eyes? :dubious:
My brother’s car-sickness stopped when we put him in the back seat. Even better when we shoved him in the trunk. 
Similarly, Disney World used to have a “ride” sponsored by (I think) American Airlines where the ending was your car heading down a runway and they would blow air in your face. The combination of air, forward motion, visuals and aircraft sound was very convincing–“Ahhh, I’m blasting down a runway at 200MPH in a tiny Disney car.”
This is one out of many stimuli that can create motion sickness. Periodic rocking in darkness or complex multi-axis rotations in darkness can also induce it, in which case it has nothing to do with the visual system.
You perform an action (jumping) and your brain expects a certain outcome (smoothly falling) but your video game gives you another. What you feel is the result of a mismatch/error signal.
Well vision vs vestibular system is certainly a big part of motion sickness.
If the options are “viewing interior of vehicle while being accelerated” and “eyes closed while being accelerated” the latter is less likely to lead to motion sickness, because there’s no conflict.
But you’re right that it’s not the only issue. There’s also the fact that you’re being accelerated seemingly for no reason.
So the ideal is a good front seat view, where instead of conflicting, your vision is helping your brain make sense of the changes in velocity.
This. It goes a long way toward explaining the appeal of IMAX films/theatres: when the projected video occupies nearly your entire field of view, it’s awfully hard for your brain to ignore the visual input that says you’re flying/falling/hauling ass, even when your inner ear says you’re sitting absolutely still.
If you are on a boat and feel seasick - the best thing to do is to look at the horizon. I think that this supports the mismatch theory. If you look at a near object, it is swaying in tune with you, but this contradicts what you inner ear is telling your brain. Th horizon is stationary so that resolves the conflict.
If I am a passenger in a car, I can’t read while being driven - i feel nauseous. Looking out of the window is fine.