Meaning of "No, yes ..."
Solution 1:
If you state a negative, and I disagree, I may start with "No" to contradict your statement, and then state the positive.
This is related to our general contrariness and bad manners.
Solution 2:
Language Log has a couple entries on this:
Yeah No
“Yeah no” mailbag
Yet another “yeah no” note
Yeah No in popular culture
Click through and read. There is no shortage of hypotheses.
I have my own hypothesis to add. I think a lot of people use the word no to mean but seriously…:
A: Where’d you get that jacket?
B: I mugged a leprechaun. No, I’ve had this thing for ages. I don’t really have much to wear with it, it’s so green.
This no has almost no negative connotation at all. It’s just sort of a verbal pivot point.
(Update: This use of no is described at length in Schegloff, Emanuel A., Getting Serious: Joke → Serious ‘no’, Journal of Pragmatics, 2001, vol. 33, no. 12, pp. 1947-1955. You can obtain the PDF here by filling out a little form.)
I think this no gets to be practically subconscious in some people’s speech, and I suspect yeah, no comes from that.
Solution 3:
The responses here have missed an emerging usage of autonegation that is more perplexing than what they have in mind. Here is an example from Language Log:
A:"Did you like the movie?"
B:"Yeah, no, it was great!"
I catch myself doing this all the time in spoken conversations, usually when elaborating an opinion. Fortunately, speakers who use this phrase always clarify their meaning; person B's response in the above example is unambiguous, even if not technically consistent.
Why "yeah, no" is used in such a way is a matter of speculation. My theory is that the "no" is used because the speaker is elaborating in order to defending against a potential disagreement.
Solution 4:
It depends on the context. Often people respond first with "no" without thinking, and then realize "yes" might be more appropriate. Maybe you could provide a certain context or quote in order to clarify.