Researchers from German's Max Planck Institute and Johannes Gutenberg University have published a paper in Nature documenting the phenomenon whereby the volatile organic compounds exhaled by cinema audiences change in synchrony while the movie plays, with specific cocktails of chemicals exhaled in response to comedy and suspense.
They call these "event-type synchronous, broadcasted human chemosignals" and propose that they could be used to fine-tune advertising and movies by measuring chemicals emitted by test-audiences in screening rooms.
The study sampled the air in a German movie theater during screenings of Hunger Games 2, Dinosaurs 3D and Buddy during the 2015 Christmas break, with audiences of around 100 people per screening.
Interestingly, the two film scene labels with the most significant linkage to chemicals measured were "suspense" and "comedy". These could be interpreted as an evolutionarily advantageous alert/stand-down signal, if perceivable by others34. Humans possess a very well developed sense of smell35, and new evidence suggests that recall is more effective36, and our perception of faces changes with odours present37. Therefore the chemical accompaniment generated by the audience has the potential to alter the viewer's perception of a film.
There are several important consequences of our finding that human beings respond to audiovisual cues through breath emissions. Firstly, in the field of medicinal breath analysis, where chemical markers for diseases such as cancer are being sought2, emotionally induced emissions have the potential to confound disease marker identification. The strong response found here for "suspense" suggests that a patient's state of anxiety should be taken into account in future medicinal breath studies. These findings also have obvious industrial applications where an objective assessment of audiovisual material is sought from groups of people, for example, in advertising, video game design or in film making.
Cinema audiences reproducibly vary the chemical composition of air during films, by broadcasting scene specific emissions on breath
[Jonathan Williams, Christof Stönner, Jörg Wicker, Nicolas Krauter, Bettina Derstroff, Efstratios Bourtsoukidis, Thomas Klüpfel & Stefan Kramer/Nature]