A Glitch in the Matrix: Avoiding this sort of thing, when it comes to virtual reality, is one of the few legitimate uses for the Out-of-Mind visual textures. (Others mostly including hiding gifts and playing really terrible practical jokes.)
A more commonly seen variant are “weavespiders”, small metallic fractal spiders (which everyone knows to ignore) used in virtual realms to collect trash, reassemble broken scenery, and otherwise do maintenance. While, obviously enough, this can simply be done programmatically without requiring any visual metaphor, reifying them like this is a simple way of avoiding the uncanny valley effect of changes “just happening” with no apparent in-world cause.
(Alternate words: Sports, singularity, safety, spectrum.)
The world was a blank.
An infinite plane stretched out in all directions, hard and smooth, white as polished ivory… only visible in context to the pure, bright, unstained white of the sky. No shadows fell, for vision here was observer-dependent, images radiating from every direction and every point necessary to illuminate everything with the same soft glow. Neutral reality.
A voice rang out over the blankness.
“Load hyperbolic spatial geometry.”
The bleached plane flickered as the underpinnings of the space it inhabited were abruptly rewritten.
“Load standard physicality-simulator physics package, atomic resolution. Ignore conflicts. Delete omniview. Delete standard plane. Fix universe size at one light-orbit, finite but unbounded. Insert constructor avatar from my personal files.”
The newly-added drifting figure grinned in the pitch-blackness that had overtaken the miniature cosmos.
“Now… let there be light.”
The Janiastre device is the simplest in a class of devices used to establish, in simplistic terms, whether or not “reality is real”; that is to say, whether or not one is currently located within a virtuality or other simulation space.
To do this, it makes use of the implementation details of said simulation spaces; to wit, that they are implemented on top of members of the well-documented families of Stannic-computable and quantum processors and thus their associated mathematical logics, and as such are incapable of simulating the rare types of computation that fall outside these families. A Janiastre device makes use of synthetic closed time-like curves to perform acausal logic-based hyperstannic computation impossible for any finite or quantum computational device, thus probing the limits of this logic space; while such computation should succeed in base reality, the underlying structure of a simulation space cannot support these trans-temporal operations and will result in randomized or erroneous results, or in the worst case, unbounded processing crash leading to a general reality failure.
It should be noted that a Janiastre device is not a universal ontology-verifier. While effective against simulation spaces based in commonly used simulation technologies, it is theoretically possible that a simulation space operating on a (hypothetical) fully-generalized acausal logic processor would be able to correctly simulate acausal hyperstannic computation, and in the limit, a sufficiently advanced technology could use a basement universe as a simulation space.
Mental Affair: Fairly common, or at least the “virtual reality” kind is; species generally don’t come equipped with the necessary hardware to do this sort of thing naturally. Popular for a variety of reasons, including obviating distance, permitting all kinds of things from, well, extra stamina to Power Perversion Potential that the material world has, ah, trouble with, and – for those having sex outside their species – making Boldly Coming work for couples who don’t share the same atmospheric composition, pressure, and temperature requirements, or have other similarly extreme physical incompatibilities.
Inside a Computer System: Well, yes, this is how virtuality works; the computers simulate the entire environment in full fidelity – which, I hasten to add, means even more when you have to come up with appropriate outputs for all possible sensory ranges of your polyspecific clientele – and then your sensory-link implants substitute this input at the sensory center of your brain. Old technology – safe, reliable, boring, been around for millennia.
Does not, I repeat, not move your consciousness anywhere – it remains in the gooey paste inside your skull, or whatever else you happen to think with. That’s what differentiates virtuality from uploading (which in any case requires quantum processors, which is by no means all of them), or voodoo – but see below.
Digisapiences, and other native digital sapients, don’t actually dwell in virtual spaces inside computers, I hasten to add. They’re programs; their senses aren’t like ours, and don’t need concepts like “space” and “shape” and even occasionally “time” to work. They inhabit the processors raw.
Finally, while it’s not technically within the meaning of this trope, most people are at least partially within computer systems at all times, mostly because – once you get into the habit – most people’s minds are too big to fit in their brains any more. Most people in advanced societies live their lives surrounded by an exoself, a sort of computational fog of data and software agents and thought-threads and daemons and suchlike doing auxiliary cognitive tasks, and since there’s only so much computational power you can cart around personally, a lot of them offload the less important parts of their current thinking to processors out there, somewhere, in the cloud. (A bit difficult, of course, when abroad – hence, the existence of, among other solutions, thinking-brain dogs.)
Digital Avatar/Myself My Avatar: Ubiquitous in the Empire and other noetic societies; as mentioned under Body Surf, people fairly regularly swap bodies for work, for visiting hostile environments, or just for the hell of it; or issue them to forked copies or fragments of themselves. Of course, that may well not count for the purposes of this trope, since it’s a body-swap rather than remote control, but equally, the same bodies can be and are teleoperated remotely by people – especially infomorphs – when the communications lag is not a problem. Also, of course, avatar instantiations are common in virtualities used for everything from work through commerce to entertainment, and in those cases, equally, one’s mind is not in the virtual body in any sort of meaningful way.
(It’s really quite hard to tell, in general, without checking the public identity tag for the long version of their name-identifier, even though it is a custom for teleoperators of physical bodies to refer to themselves through them as “this extension” rather than “me”.)
Born As An Adult: Notable on this point, principally, are a lot of digisapiences whose first body, is, naturally, exactly the same as all the other robots or bioroids of the same model. Of course, they’ve usually had a fairly long life in virtuality before then, so it’s not like they’re being born void of experience.
Although they may have had to internalize that in the physical world, those inconvenient thermodynamic laws mean you can’t unbreak china or descramble eggs.