Scary Movies Fill the Air in a Cinema with Fear Pheromones

Gauging fear pheromones in movie-theater air indicates audience tension levels.

Posted Nov 04, 2018

Scary movies are dominating the box office. According to a November 3 article in Forbes magazine, the latest Halloween sequel has raked in over $200 million worldwide and Marvel Comics’ spooky Venom has grossed just as much in the United States alone. The Motion Picture Association of America (MPAA) gave Halloween (2018) an R rating due to ”horror violence and bloody images, language, brief drug use, and nudity.” Some parents think Venom is way too scary for children under 13 and should be R-rated; nevertheless, MPAA only gave the film a PG-13 (parents strongly cautioned) based on what they describe as “intense sequences of sci-fi violence and action, and for language.”

J. R. Eyerman/The LIFE Picture Collection/Getty Images
Formally-attired audience sporting 3-D glasses during an opening night screening of "Bwana Devil," the first full-length color 3-D (a.k.a. 'Natural Vision') motion picture, at Paramount Theater in 1952. 
Source: J. R. Eyerman/The LIFE Picture Collection/Getty Images

The MPAA created their movie rating system in 1968 as a tool for parents to determine if a particular film was appropriate for their children of different ages. Movie studios avoid R ratings like the plague because 13- to 16-year-old teens buy a lot of movie tickets and age restrictions limit box office potential. R-rated stands for “Restricted” and means that any filmgoer under 17-years-of-age must be accompanied by a parent or adult guardian. That said, oftentimes, the makers of really scary horror films can negotiate a PG-13 rating by making some last-minute edits to appease the MPAA. Unfortunately, movie ratings are highly subjective and, until now, there wasn’t a scientific way to gauge whether or not a particular movie is actually kid-friendly.

For the first time, a group of researchers from the Max Planck Institute for Chemistry in Mainz, Germany has identified a quantifiable measurement for determining the appropriate age rating for a movie based on the amount of fear pheromones released into the air while an audience is screening a film. The journal PLOS ONE published these findings October 11 in a paper, “Proof of Concept Study: Testing Human Volatile Organic Compounds as Tools for Age Classification of Films.”

Humans emit a wide range of volatile organic compounds (VOCs) through our skin and when we exhale. The composition of these emissions is influenced by environmental factors that trigger various emotional states. For this study on parental guidance ratings, the researchers assessed multiple VOCs in movie-theater air based on 135 screenings of 11 different films. The data was collected over eight weeks from two separate cinemas and involved over 13,000 filmgoers.

As you can see in the YouTube video above describing this study, the Max Planck researchers found that the amount of a pheromone called “isoprene” in the cinema air was correlated with how the movie industry had rated a film. For example, a G-rated film that was deemed appropriate for all ages would result in audience members secreting much less isoprene into the air than a slasher film rated NC-17 (No one 17 and under admitted).

Microscopic amounts of isoprene are released into the air whenever we move our muscles. The more stressed out and nervous moviegoers are during a particular scene in a film, the more people tend to wriggle in their seats, and the audience collectively emits more isoprene into the air.

"Evidently, we involuntarily squirm back and forth on our cinema seat or tense our muscles when we become nervous or excited," Jonathan Williams, group leader at the Max Planck Institute for Chemistry and senior author of this paper, explained in a statement. “Isoprene appears to be a good indicator of emotional tension within a group. Our approach could, therefore, provide an objective criterion for deciding how movies should be classified.”

Audience Members Create Unique Pheromone-Related Fingerprints in the Air

Beyond the realm of movie ratings, this research is fascinating because it suggests that we might be able to “smell” fear in the air on an unconscious level. For this study, the scientists hooked up a mass spectrometer to the cinema’s ventilation exhaust system and tracked changes in air composition every 30 seconds. Their equipment is so sensitive that it can pick up minute quantities of human VOC at ppt levels of "one part per trillion."

With more research, this technology could be fine-tuned as an empirical tool for objectively measuring the degree of fear elicited by a scary horror movie such as the latest Halloween. In disputable cases between a PG-13 or R rating with movies like Venom, the exact amount of isoprene created by a test audience could help the MPAA give parents more science-based ratings. Someday, in addition to the current parental rating system, there might also be a "Human VOC" rating given to films based on the quantity of human volatile organic compounds an audience released while viewing the movie. 

Jonathan Williams is currently collaborating with researchers at the Max Planck Institutes in Frankfurt and Nijmegen to investigate specific airborne chemical fingerprints created during a wide range of emotional states. For this research, his team will measure human VOCs being emitted by individual study participants under more stringent laboratory conditions than is possible in a movie theater. The million-dollar question is whether other human emotions beyond fear-based responses leave identifiable VOC signatures in the air. Stay tuned!


C. Stönner, A. Edtbauer, B. Derstroff, E. Bourtsoukidis, T. Klüpfel, J. Wicker, J. Williams. "Proof of Concept Study: Testing Human Volatile Organic Compounds as Tools for Age Classification of Films." PLOS ONE (First published: October 11, 2018) DOI: 10.1371/journal.pone.0203044

Jill D. Fenske and Suzanne E. Paulson. "Human Breath Emissions of VOCs." Journal of the Air & Waste Management Association (First published online: December 27, 2011) DOI: 10.1080/10473289.1999.10463831