The shark draws near… [music from Jaws]. Janet Leigh takes her shower and a shadow appears behind the curtain… [music from Psycho]. The teenager Regan contorts, writhing back in forth more than is humanly possible [music from The Exorcist]. We as viewers are in no danger, yet these scenes frighten us. How is that we forget it’s only cinema? Read on to learn why.

Rather than questioning the nature of emotions elicited by the film, as philosophers might do (are they real emotions?), Olivier Koenig, a professor of cognitive neuroscience at the University Lumière Lyon 2 (France), would rather explore the emotional mechanisms. According to the researcher, one of the central elements of these mechanisms is the amygdala, which “is activated when a person feels an emotion, provoking a bodily reaction.” Thus, for example, when we’re angry or frightened, this brain area (in the form of an almond) is solicited. The neuroscientist adds that the area is also activated at the sight of a glass of water when we’re thirsty. Our ability to quickly determine what is vital to us depends on the amygdala. The amygdala functions unconsciously, making it highly efficient to the extent that the conscious perception of the stimulus isn’t necessary in order for this ancient part of the brain to become active. Subliminal messages are a particularly good illustration of this feature: if we don’t have time to “see” them, our amygdala detects them and triggers emotion.

The strength of the emotional mechanisms doesn’t necessarily depend on the reality of the situation. Whether we experience the situation ourselves, imagine it, or see someone else experiencing it changes (almost) nothing: the emotion elicited and our body’s reaction is (almost) the same. How is this possible? It’s possible due to the intervention of certain types of neurons; those that make laughter, tears and yawns contagious: mirror neurons. These are the same neurons that, as children, make us hide beneath the covers when we’re told a ghost story, that make us cry when we see Bambi (and later when Jack sinks to the bottom of the ocean in Titanic), and that have us cowering when Hannibal Lecter or T-Rex appear on the screen.

At the movie theater, we sink further into our chairs, but we stay, emphasizes Olivier Koenig, because “somewhere” we know it’s not real. According to the researcher, that “somewhere” is located in the medial temporal lobe of the brain. It’s episodic memory that encodes the context and keeps the brain from behaving as it would in a real life situation. It’s this area that helps us remember we're spectators rather than actors.