Halliday & Matthiessen (2014: 174):
What is the meaning of polarity in interrogative? In a yes/no interrogative clause, which is precisely a request for polarity and hence presumably cannot itself pre-empt the choice, both positive and negative can occur; and here the negative does appear as a marked option, in that while the positive contains no suggestion regarding the likely answer, the negative is, in the traditional formulation, a ‘question expecting the answer “yes” ’ …
In fact the typical meaning is slightly more complex than this formulation suggests; what the speaker is saying is something like ‘I would have expected the answer yes, but now I have reason to doubt’. How then is the negative question answered? The responses yes, no state the polarity of the answer, not the agreement or disagreement with that of the question:Haven’t you seen the news? – No (I haven’t). Yes (I have).– whereas some languages reverse the pattern, or (like French, German and Swedish) have a third form for the contradictory positive term.