Depends if you're writing for TV or a book.
On TV, you are pressed for time and would typically be observing the reaction from outside. Then something dramatic, resembling an epileptic seizure with their hair catching on fire is appropriate. You can also go with the matrix-style download, where seizure is followed by a sudden revelation.
In a science fiction book on the other hand, the author will typically focus on the first-person experience of having your brain over-loaded. Or if written from an outside perspective, at least make it more drawn out, like a prolonged illness. It's not uncommon to describe reactions akin to hallucinations and fever-fantasies, where the person is babbling about things the others around him can't see or does not understand. Fred Hoyle's "The Black Cloud" employ this strategy, where the overloaded person is bedridden and eventually dies from the massive re-organisation his brain is undergoing. A change in personality is another common trope in this situation.
You could also go with a more heart-breaking angle where the person feels overloaded and where taking in and processing the information is at the expense of other tasks, like remembering to eat and dress yourself, find your way around a town or being unable to retain personal memories of the day. In short: You portray the onset of dementia.
Again from a strict story-writing perspective, I think you have to first ask what you want to accomplish with the scene where the person is overloaded and where you want the story to go, and only then do you select the proper symptoms of overloading.
the BIOS is overloaded? – Mathmagician – 2017-08-13T03:00:10.640
He falls asleep in class. – JDługosz – 2015-06-29T18:29:59.383
2
Is the information in your scenario injected via the senses or “directly”? Anyway, sensory overload seems to be a relevant term.
– Wrzlprmft – 2014-10-19T12:19:30.2207Consider that there is a lot more going on all the time, even within your ability to notice, than you consciously recognize, most of which goes by "unnoticed". – a CVn – 2014-10-19T14:43:41.493
This is pretty simplistic, but think of it this way: in theory your brain can contain any amount of information but can only process a very limited amount of it at a time. So, yeah, pipes can get clogged up. However, the mechanism of information injection is up to you and you can decide that the data stored bypasses the subject's attention mechanism. Of course, in a situation like this it would require more effort to retrieve any specific fact. – lea – 2014-10-19T15:09:47.747
1I think what happens is dementia. – overactor – 2014-10-19T16:47:51.060
2As we are in constant triaged overload every moment already, I think the idea they are conveying is likely the rapid, forced generation of synapse pathways, and not just an "exposure" to the information. Actually forcing rapid generation of synaptic pathways may or may not be painful (but we lack nerves in the brain, so... probably not), but the movie would be rather anti-dramatic if the character suddenly received a forced "upload" and didn't respond other than to say "Oh, yeah. Got it." – zxq9 – 2014-10-21T05:06:52.713