At first blush, I think it might be anticipating the question, but I think it goes an order or two magnitude beyond that (if you follow me). It usually takes a form like this;
Person 1:" is that Cash or Credit?"
Peson 2: Visa.
Person 2 went ahead and answered the “next” question that Person 1 was going to ask next, and in so doing, answered both.
If I were to explain, succinctly what person 2 did here, what would I say?
I’d call it impatience with programmatic BS, but you’re probably looking for something more English Departmenty.
I would say that he answered with more specificity than was asked for, with the answer to the original question being implied.
It seems similar to the concept of enthymeme in logic. An unstated premise that leads to the conclusion. Perhaps it could be called a conversational enthymeme or some such.
In other words, enthymeme is skipping a step because it’s implicitly understood.
I would say they didn’t answer the question as given.
I think you’re all giving person 2 too much credit(heh). Generally when a cashier asks cash or credit, that is all the information they need. If doesn’t matter if it’s Visa/Mastercard/Amex/ Discover or anything else, the register can process them all from the ‘credit’ selection.
This may or may not be what you’re asking about, but your question is related to conversational implicature:
Normal conversations usually flow along in a manner that’s not like a strictly logical argument. There are various ways of formulating the implicit assumptions that people make. One such way is the Gricean maxims. One of the maxims is the assumption of relevance. Since the answer to that question was neither of the choices given, Person 1 will assume that Person 2’s answer is somehow relevant to the choice between credit and cash. Since Visa is a credit card, Person 1 will assume that Person 2 means that they are using a credit card and, furthermore, the card will be Visa.
For some reason at the vet office I use, they do need to know. You swipe your card yourself, so they don’t see it but they always ask.
It does matter, because not all cards are accepted everywhere you want them to be (yes, I even had my Visa declined!).
I noticed an example today where this pattern was actually expected. Someone asked me if I knew what time it was. I imagine he would have been quite confused if I had answered “yes”. In fact, he probably already knew that, from seeing the watch on my wrist. Instead, I anticipated the next question, and said “two thirty”.
When I was driving trucks, I would often get a call asking - “Where are you” or “how are you getting on?”
My reply would usually be something like "Two thirty, or “Three 'O clock.”
The reason being, that the questioner would not really be interested in the literal answer to their enquiry, but actually wanted to know when I would arrive at my destination.
I was rarely wrong.
Someone asking “Chronos” the time is news?