The Question of Smack 'Em Yak 'Em

Airplane: one of the best movies of all time. I challenge you to watch it and not instantly fall in love with it, then spend the next week quoting every single line you can remember to every single person you can find, gradually losing friends and acquaintances because every time they start a word with an s-sound you yell "DON'T CALL ME SHIRLEY" which makes discourse very difficult, and finally finding yourself alone in a corner mumbling, "Good luck. We're all counting on you," to the wall while the world passes serenely by, which is fine, because Airplane is one of the best movies of all time.

Cyclical crazy rant aside (one more: never watch Airplane with your grandmother), the movie is in fact relevant to the question of language comprehension. One scene in particular illustrates this. The movie was released in 1981, when what is now African American Vernacular English was called jive and was, apparently, the hippest slang on the block. Airplane parodied jive in this scene:

First Jive Dude: Shiiiiit, maaaaan. That honky muf' be messin' mah old lady... got to be runnin' cold upside down his head, you know?
Second Jive Dude: Hey home', I can dig it. Know ain't gonna lay no mo' big rap up on you, man!
First Jive Dude: I say hey, sky... subba say I wan' see...
Second Jive Dude: Uh-huh.
First Jive Dude: ...pray to J I did the same ol' same ol'!
Second Jive Dude: Hey... knock a self a pro, Slick! That gray matter backlot perform us DOWN, I take TCB-in', man!
First Jive Dude: Hey, you know what they say: see a broad to get dat booty yak 'em...
First Jive Dude, Second Jive Dude: ...leg 'er down a smack 'em yak 'em!
First Jive Dude: COL' got to be! Y'know? Shiiiiit.

This was obviously an exaggeration of the dialect, but the point is clear: it's incomprehensible. The movie even puts in subtitles a standard English translation. I'll let Youtube fill in the details:

http://www.youtube.com/watch?v=mRDOp6zypbM

The point the movie is trying to make is that some vernacular English dialects are so far removed from standard English that trying to understand them in the context of standard English is absurd. The question is: which of these differences from standard English exactly makes it so hard to understand? The sounds are obviously different, and the syntax is very liberal too. But even reading through the dialogue, and listening to the audio repeatedly, the meaning might still be lost on us, even when each word individually and in the context of a sentence is understood perfectly. (By context of the sentence, I mean the role the word plays in the sentence; if I say "That yaxoodle totally shumptified my bizzlack!" you understand that yaxoodle is the noun shumptify is the verb, and bizzlack is the direct object, but that serves nothing towards helping your understanding of its meaning.)

We have no reference point from which we can draw meaning from the vocabulary, and so the meaning remains hopelessly incomprehensible. This leads to my general point: if when talking to someone who speaks your language, sounds and syntax differ from what you're used to, comprehension may at first be difficult but it rapidly becomes obvious what they mean. I think that this is because, based on the wealth of your experiences, you are aware of what the words your companion is using are, how they sound in different circumstances, and the different things they mean depending on their order. You can usually parse meaning out of the most jumbled of sentences as long as you are aware of the definitions of the words. And even if the accent is one you've never heard before, my own experience tells me that while the incomprehension time may last a bit longer, we adapt remarkably quickly to new accents and are able to understand meaning with ease in short amounts of time.

But listen to someone talk using unfamiliar slang or obscure jargon, and you're out of luck. There simply is no reference to draw from when faced with words you've never encountered before. You have to either learn them from context, which takes much longer time, or you have to have them explained explicitly to you. While all three features - sounds, syntax, and vocabulary - can be obstacles to your comprehension, only vocabulary can be potentially an insurmountable one, and it is for that reason it is the most important feature in language comprehension.

(Watch Airplane!)