Odor emitted by moviegoers reveals the nature of the film

Cinema odor research, IG nobel 2021 prize for chemistry, reveals that we can identify the type of film being shown by analyzing the miasmas of the audience in the theater.

The response of the human body to certain stimuli from the outside world is a rather complex phenomenon, which the scientific community generically calls "emotional reaction analysis".

This is the kind of research that identifies and analyzes the reactions of humans to certain emotions, for example those procured by viewing a particular photograph or listening to a sound that is either completely familiar or, on the contrary, completely unfamiliar.

The last frontier of the analysis of the emotional reaction - at least according to the judging committee that every year awards the IG nobel prizes to the strangest researches of the year - is that of the study of the smells emitted by the spectators in the cinemas, which are believed to define the nature of the film shown.

The Study of Volatile Organic Compounds

The study, developed starting in 2015 by a team of researchers from the Johann Gutenberg University of Mainz, bears a rather telling title: "Analysis of Cinema Data: The Smell of Fear".

The scientists start with a couple of fundamental questions, which the study incredibly manages to give a rather structured answer to: do humans communicate through the emission of odors, like other mammals? And if they do, what do the odors emitted mean to communicate?

The answer comes from the analysis of so-called VOCs, the volatile organic compounds emitted by humans. VOCs, in fact, encompass a plethora of chemical compounds, from paint thinners to liquid hydrocarbons, all of which share a high volatility - a characteristic that is also inherent in the fumes and miasmas produced by humans, from perspiration onwards.

In all of this, the cinema immediately seemed like an ideal context for the study: "it's a closed box, so it's completely controllable," says Jörg Wicker, one of the authors of the study.

In cinemas, moreover, there are generally many people exposed to the same visual stimuli at the same time, and they are enclosed in a fairly small space.

Our odor reveals film content

The research reveals that human volatile emissions recorded inside movie theaters are linked "to the semantic content of the films shown".

The experiment involved a multiplex for a duration of 4 weeks, during which the odors emitted by more than 9 thousand spectators, who watched six different films, were analyzed.

To better narrow the scope of the research to easily recognizable emotions, the researchers selected six films in total: Peter Jackson's "The Hobbit," "Hunger Games: The Girl on Fire" and "Machete," plus two family comedies and a horror film, "The Marked Ones."

Well, the results of the curious research are astounding: the scientists found that certain VOCs become predominant based on the type of scenes the film offers to the movie theater audience.

Blood and violence-laden scenes, for example, had high emissions of ammonia, which makes perfect sense since ammonia is also found in sweat - a typical human reaction to anxiety and stress, including visual stress.

In addition to ammonia, audiences subjected to horror and bloody scenes emit a lot of acetone, a compound that is generally associated with physical activity and anxiety.

In front of the comedies and good feelings, there was a predominance of formaldehyde: the data, explain the scientists, is more than compatible with healthy laughter in the hall, because formaldehyde is known to be one of the "pollutants" most present in the human body, due to the natural decay of artifacts and buildings that employ it.

Suspense or particularly romantic images, on the other hand, are associated with the emission of isoprene, a VOC similar to acetone, connected to the excitement of physical movement and the archaic urge to escape.

A comical touch to the research, which definitely deserved the IG nobel, is given by the analysis of the scenes that presented accidents: the emission most present inside the room is that of siloxanes, absolutely not present inside the human body. "It would seem to make no sense" admit the scientists, until you realize that siloxanes are present in a large amount of cosmetics and shampoos.

Facing an accident on the screen, explain the researchers, "viewers tend to get hot and therefore undress", releasing into the air the residues of creams, cosmetics and perfumes.