In "Fearing Fictionality," Kendall Walton explores various arguments for what exactly is going on when Charles purports to be frightened by a movie featuring a monstrous green slime.
"Charles is afraid, it is assumed, and he does not think he is in danger. So fear does not require such a belief. One then cooks up a weaker requirement so as to protect the initial assumption: Fear requires only imagining danger, it is said, or the idea of danger vividly presented" (179).Walton goes on to argue that the problem with this requirement lies in our initial assumption: that Charles actually is afraid, that what he is feeling really is fear. Pointing out that fear of something that does not exist (such as a malicious green slime) cannot possibly be the same as fear of something that does (airplane rides or rabid dogs), Walton comes up with the concept of "quasi-fear."
However, I don't take this problem of existence to be an issue, because it seems to me that fear requires one to imagine danger always, not just in the case of experiencing fiction.
During a class discussion, a classmate brought up the point that when we recognize danger in real life, it is because we imagine the potential consequences of the situation. What we're actually afraid of is something that has yet to happen. A girl who feel afraid when she sees a dog is not afraid because it is biting her, but rather because she imagines a sequence of events where the dog ends up biting her.
Of course, Walton might argue that this example is different from the example of the green slime, because the actually exists and is right there in front of her. However, I don't think that Walton would want to say that, when the same girl walks down a dim alley alone at night and feels fear, her fear isn't real just because the muggers she imagines may or may not exist. Walton's response to this example would be that even though the muggers may not actually exist, it is realistically possible for them to exist--there is no doubt in Charles' mind that there is no such thing as a green slime. In each of these cases, she believes that the danger she imagines might actually occur.
From my perspective, the requirement of belief is a jump. The student I referred to previously used an example, not of fear, of falling in love with a person you see walking on the opposite side of the street. Just as fear is a result of an imagined sequence of events, so love in this case is the result of you imagining that this person is more than just good looking but also charming and kind, that he or she returns your affections, and that you will be a good couple. None of these things have taken place, and the likelihood of them occurring is slim-to-none (I am only a little more likely to end up marrying this person than I am to marry Mr. Darcy). And yet we wouldn't want to call this feeling "quasi-attraction" instead of real attraction.
That example is not perfect, of course. But the main point is this: the object of our fear is always fictional, because fear necessarily precedes consequences (if it didn't, it wouldn't be a very useful feeling as we'd have little cause to avoid danger). Our capacity for determining and reacting to real life consequences appears to be identical to our capacity to responding to events in fictional works; our imagination seems to be used in the same way in both cases.