Lets say someone who can speak 4 languages fairly fluently is being spoken to by 4 different people each speaking a different language. Excluding the obviously confustion that would ensue from being spoken to 4 different people, would the quattro-lingual be able to follow each language as well as he would talking to just 1 person?
Also, if I never learned to read, what would that part of my brain be used for?
Perhaps a more useful question would be, would it be harder to listen to four people speaking simultaneously in four different languages than if they were all speaking the same language?
as far as the part of the brain used for reading goes, I doubt it’s used solely for reading, so its other functions would still probably take place. we only began reading in the last few thousand years, so I doubt that part of our brain stayed dormant waiting for books.
There is not a part of your brain that is “for” reading. Reading has only been a part of human activity for a very short time. A non-literate person uses his brain for the same things you do. He may also develop other abilities that you and I haven’t, such as the ability to remember things without having to write them down. Much of the Bible (and other mythology and ancient tales) is basically “oral literature,” stories that were passed down from person to person through story telling.
I understand that there isn’t a specific section of the brain for reading. But when learning to read, your brain is rewired so that you are able to read (I might be wrong, read it in TIME). I might be changing my question completely but, if my brain was never rewired, how would it function differently?
I think I addressed that. You would rely more on memory, for one thing. Some non-literate people have amazing memories for detail. Minstrels in the Middle Ages did all of their singing from memory, for example. Great lengthly sagas were committed to memory by people of lots of pre-literate cultures. What else you used those capacities for would depend entirely on your influences in childhood.
Oh yea, my fault. I read your first response wrong.
I haven’t had the chance to do that with four languages yet, but I’ve done it with three. (Japanese, French and English.) You will always understand your mother tongue better, regardless of the situation. For the rest, IME, you can follow as well as if all three speakers spoke in the same language. The only problem I had was that after a while, I’d occasionally mix up words when answering.
Somewhat related, I can read subtitles and listen to a movie at the same time. (In two different languages, of course.) It is a bit more tiring, mentally, but it’s possible.
It might be worth mentioning that this is something that us Scandinavian types learn to do in an early age (lots and lots of exposure to subtitled programmes) and those of us who understand the spoken languange well enough find it not in the least tiring. Indeed, sometimes being able to simultaneously listen to a show and read the subtitles actually enhances your viewing experience (listening enables you to get puns etc. that are sometimes hard or even impossible to translate, while reading the subtitles means you don’t have to hear/catch every word said.)
I´m assuming you don´t mean the four people would all be speaking at you at exactly the same time, but in the same conversation. If four people are all speaking at you at once, it´s pretty impossible to understand fully what everyone is saying, in my experience - no matter how many languages.
At our house at dinner, you can frequently hear three languages at the same time, as we speak different languages with our parents, and my brother and I speak all three with each other, depending on the topic (google for codeswitching). So if there´s a lively discussion going on, it might well be in all three of them. I´m used to it, so for me it is really no more confusing than any conversation with three other people who may be interrupting each other (and me answering and interrupting, too). If we have guests, it´s even more fun. 
I speak these languages at a native level - but it also works with Spanish, which I speak fluently but not as a native language, and two of my native languages. No experience with four, but I imagine it would be similar.
If you have to concentrate on a language because you´re not that fluent in it, it gets harder, because you have to allocate more brain resources to understanding that one language.