Controlling the Reader's Interpretation

Question: What is the correct name given to the guess that you make on what is happening in a story based on what the narrator tells you?

Answer: I believe what you are referring to is narrative inference or supposition, though there's probably a classical term invented by the Greek rhetoricians.

Of course, everything we know about a story is based on what the narrator tells us. So the question of inference or "guessing" arises when a writer tries to mislead or confuse a reader, perhaps to make the story's ending a little less predictable or to reflect the ambiguity of life. In that case, you might use a narrator who has a limited perspective and is unaware of certain facts, forcing the reader to infer them. You may also choose an unreliable narrator who wants to deliberately mislead the reader or simply has a slanted view of the events he is describing. Readers like to solve puzzles and will keep reading to see if their guesses are right.

Even if you are using an omniscient narrator, you can influence a reader's expectations by misdirection (e.g. red herrings), foreshadowing, or the withholding of certain information. These techniques force the reader to make inferences that may or may not turn out to be correct.