How often do people say "gotta", "wanna" or "gonna" in English speaking countries?
As an American, I can report that everyone I know, even highly educated people, use these forms several times a day. People in business meetings, professors giving lectures,... everyone. Sometimes people are being slow, clear, and deliberate, in which case they will pronounce the full phrase, which does sound more formal by comparison.
My sense, as an amateur linguist, is that the problem lies on the fact that it is difficult to quickly turn the vocal cords on and off. (Please note that "gotta" is actually pronounced /g'ɒdə/, with a d sound) It takes time to slow down and make the change. In each of these examples, the entire word is pronounced with voiced sounds. These types of drifts happen in every language and lose stigma over time.
As far as I know, everyone seems to use it. It's like an unavoidable speech habit, that even the "educated people" have.
It's called "assimilation", and refers to how words are "run in" together. They kind of join up and it makes speaking much easier, instead of painstakingly breathing out every single syllable clearly.
This happens in all sorts of languages, and among all sorts of people. So yes, to answer your first question, these words are used rather commonly in oral English, especially in America.
Your second question: In most cases yes. In formal situations, people try to avoid using them, instead going for their more "correct" form, such as "going to" instead of "gonna". Example: a television news program, where the newsreader musn't slur his words.
I concur with the three who have chimed in.
I wanted to add that, unlike contractions, such assimilations are spoken forms. They are rarely written, especially outside of quotation marks.
That said, I did some research to verify my assertion, and it appears erroneous. Gotta is making its way into literature, particularly when authors want to convey something exciting, informal, or hip. An amazon search returned almost one thousand books with the word Gotta in the title; they include:
- 10 Things You Gotta Know About Choosing a College
- If You're Trying To Get Better Grades & Higher Test Scores In Social Studies You've Gotta Have This Book
- You Gotta Have GUTS!
- Stuff You Gotta Know: Straight Talk on Real Life
- A Guy's Gotta Eat
- A Woman's Gotta Do What a Woman's Gotta Do
- The Teen Girl's Gotta-Have-It Guide to Money
- Uh Oh! Gotta Go!: Potty Tales From Toddlers
- and, my personal favorite: You Gotta-Wanna (a book about sales advice)
Still, I'm not sure if these authors would assert that gotta is standard English, just because the term has worked its way onto the covers of their books; the use of non-standard English appears to be purposeful. Still, I gotta admit, I was surprised.