Suspense

Suspense is a feeling of uncertainty and anxiety about the outcome of certain actions, most often referring to an audience's perceptions in a dramatic work. Suspense is not exclusive to fiction, though. Suspense may operate in any situation where there is a lead up to a big event or dramatic moment, with tension being a primary emotion felt as part of the situation. In the kind of suspense described by film director Alfred Hitchcock, an audience experiences suspense when they expect something bad to happen and have (or believe they have) a superior perspective on events in the drama's hierarchy of knowledge, yet they are powerless to intervene to prevent it from happening. In broader definitions of suspense, this emotion arises when someone is aware of his lack of knowledge about the development of a meaningful event; thus, suspense is a combination of anticipation and uncertainty dealing with the obscurity of the future. In terms of narrative expectations, it may be contrasted with mystery or curiosity and surprise.

Aristotle
According to Greek philosopher Aristotle in his book Poetics, suspense is an important building block of literature. In very broad terms, it consists of having some real danger looming and a ray of hope. The two common outcomes are: If there is no hope, the audience will feel despair. Something other than the danger happening is a deus ex machina.
 * the danger hitting, whereby the audience will feel sorrowful
 * the hopes being realised, whereby the audience will first feel joy, then satisfaction.

Zeigarnik effect
In psychology, the Zeigarnik effect states that people remember uncompleted or interrupted tasks better than completed tasks.

Soviet psychologist Bluma Zeigarnik first studied the phenomenon after her professor, Gestalt psychologist Kurt Lewin, noticed that a waiter had better recollections of still unpaid orders.

In Gestalt psychology, the Zeigarnik effect has been used to demonstrate the general presence of Gestalt phenomena: not just appearing as perceptual effects, but also present in cognition.

The Zeigarnik effect suggests that students who suspend their study, during which they do unrelated activities (such as studying unrelated subjects or playing games), will remember material better than students who complete study sessions without a break.

Some authors have tried to explain the "paradox of suspense", namely: a narrative tension that remains effective even when uncertainty is neutralized, because repeat audiences know exactly how the story resolves (see Gerrig 1989, Walton 1990, Yanal 1996, Brewer 1996, Baroni 2007). Some theories assume that true repeat audiences are extremely rare because, in reiteration, we usually forget many details of the story and the interest arises due to these holes of memory (see Brewer); others claim that uncertainty remains even for often told stories because, during the immersion in the fictional world, we forget fictionally what we know factually (Walton) or because we expect fictional worlds to look like real world, where exact repetition of an event is impossible (Gerrig). The position of Yanal is more radical and postulates that narrative tension that remains effective in true repetition should be clearly distinguished from genuine suspense, because uncertainty is part of the definition of suspense. Baroni (2007: 279-295) proposes to name rappel this kind of suspense whose excitement relies on the ability of the audience to anticipate perfectly what is to come, a precognition that is particularly enjoyable for children dealing with well-known fairy tales. Baroni adds that another kind of suspense without uncertainty can emerge with the occasional contradiction between what the reader knows about the future (cognition) and what he desires (volition), especially in tragedy, when the protagonist eventually dies or fails (suspense par contradiction).