Suspense is a crucial characteristic of the thriller genre. It gives the viewer a feeling of pleasurable fascination and excitement mixed with apprehension, anticipation and tension. These develop from unpredictable, mysterious and rousing events during the narrative, which makes the viewer or reader think about the outcome of certain actions. Suspense builds in order to make those final moments, no matter how short, the most memorable. The suspense in a story keeps the person hooked to reading or watching more until the climax is reached.In terms of narrative expectations, it may be contrasted with curiosity and surprise. The objective is to deliver a story with sustained tension, surprise, and a constant sense of impending doom. As 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.Suspense in thrillers is often intertwined with hope and anxiety, which are treated as two emotions aroused in anticipation of the conclusion - the hope that things will turn out all right for the appropriate characters in the story, and the fear that they may not. The second type of suspense is the "...anticipation wherein we either know or else are fairly certain about what is going to happen but are still aroused in anticipation of its actual occurrence."[6]According to Greek philosopher Aristotle in his book Poetics, suspense is an important building block of literature, and this is an important convention in the thriller genre.[7]Thriller music has been shown to create a distrust and ominous uncertainty between the viewer of a film and the character on screen at the time when the music is playing.[8]Common methods and themes in crime and action thrillers are mainly ransoms, captivities, heists, revenge, kidnappings. Common in mystery thrillers are investigations and the whodunit technique. Common elements in dramatic and psychological thrillers include plot twists, psychology, obsession and mind games. Common elements of science-fiction thrillers are killing robots, machines or aliens, mad scientists and experiments. Common in horror thrillers are serial killers, stalking, deathtraps and horror-of-personality. Elements such as fringe theories, false accusations and paranoia are common in paranoid thrillers. Threats to entire countries, spies, espionage, conspiracies, assassins and electronic surveillance are common in spy thrillers.[9]Characters may include criminals, stalkers, assassins, innocent victims (often on the run), menaced women, psychotic individuals, spree killers, sociopaths, agents, terrorists, cops and escaped cons, private eyes, people involved in twisted relationships, world-weary men and women, psycho-fiends, and more. The themes frequently include terrorism, political conspiracy, pursuit, or romantic triangles leading to murder. Plots of thrillers involve characters which come into conflict with each other or with outside forces.[10]The protagonist of these films is set against a problem. No matter what subgenre a thriller film falls into, it will emphasize the danger that the protagonist faces. The protagonists are frequently ordinary citizens unaccustomed to danger, although commonly in crime and action thrillers, they may also be "hard men" accustomed to danger such as police officers and detectives. While protagonists of thrillers have traditionally been men, women lead characters are increasingly common.[11] In psychological thrillers, the protagonists are reliant on their mental resources, whether it be by battling wits with the antagonist or by battling for equilibrium in the character's own mind.