This is Cristina Cumpanasoiu’s first blog post, which she wrote as a student of my MA course Testing Prescriptivism:
Slurring words together is common in literally every language. It’s kinda inevitable even for highly educated people. From poorly trained teenagers to (supposedly) well-read doctors and professors (linguists included) I’ve heard them all using gonna instead of going to during their lectures and wanna instead of want to in order to express future with first, second and third person singular and plural.
In linguistics, this phenomenon is called assimilation and it refers to a phonological process by which a sound becomes more alike to a nearby sound making speech “easier”. In more formal situations people will try to avoid using gonna or wanna (imagine your boss asking you during a job interview “wanna tell me about your experience?”) going for the correct, or I should say, the accepted form want to or going to. But let’s face it, you’ve used it! Sometimes due to the situation you were in, or maybe because you were not very confident about your English and using wanna felt as if you sounded close to being a native speaker.
Wanna and gonna even made their way into literature, especially among writers aiming at a young, fun and modern audience. My curiosity pushed me into searching Amazon for books including the word wanna in their title and these are five of the books I found:
The Nothing Book: Wanna Make Something of It? (Crown, 1974), I Wanna New Room by Karen Kaufman (2010), Wanna Get Lucky? by Deborah Coonts (2010), Wanna Cook?: The Complete, Unofficial Companion to Breaking Bad by Ensley F. Guffey (2014), I Wanna be a Pirate by Tom Pasinski (2014).
No, this is not an advertisement for Amazon books (or for t-shirts by floozees doozees …), but the titles show the sorta path by which wanna is entering literature.
Whatever the reasons we might have for using gonna and wanna, the forms are frequently found in colloquial speech, particularly in American English. And it is striking that although gonna and wanna are now mainstream in spoken and colloquial written American English, they are still not accepted by Merriam Webster’s Collegiate Dictionary.
Bridging the Unbridgeable 
Here’s a link to a recent blog post by my colleague, Marcel Lemmens, on the subject of assimilation in Dutch: http://taalpraat.nl/2014/03/half-woord/.
Although it’s a very common phenomenon in speech, my impression is that it finds it far more difficult to encroach into the written language. Or have I just not looked far enough?
It is undeniable that “going to” is frequently pronounced “gonna,” but it is perhaps worth noting that this assimilation is possible only with the grammaticalized use of “going to” – as a future marker and nothing more. If someone says, “I’m gonna have lunch at 1 o’clock,” we understand that as a statement about the future.
But when “going to” retains its full verbal sense involving physical motion, it never assimilates to “gonna.” “I’m gonna Paris on Thursday” is not a possible sentence.
We recognize the difference, which can be subtle, and we understand the difference (though I suspect that most English speakers would be hard-pressed to explain what grammaticalized “going to/gonna” is).
“I’m gonna have lunch” is future tense – maybe a half hour from now, maybe two hours from now, and maybe next week. (“I’m gonna have lunch on Thursday after I see the doctor.”)
But if someone says, “I’m going to have lunch,” they’re most likely stepping out of the door and heading for the restaurant. “I’m on my way.”
“gonna” is de rigueur amongst BBC broadcasters. Every “Today” programme on Radio 4 is riddled with “gonna” here and “gonna” there.