In cartoon worlds, squiggly lines over characters are reserved for exceptionally smelly people. But in reality, everyone deserves those little kinks: Each of us is constantly emitting a steady stream of gases and microbes, as well as odors. And those gases may reveal more about us than what we last ate (and whether or not we agreed). Our gases can also reveal what we think about movies.
In a study involving 9,500 moviegoers, researchers found that the chemicals viewers emit while watching a movie vary reproducibly depending on the type of scene they watch. Specifically, the researchers noticed synchronized changes in the amounts of specific gases during funny and exciting bits of film. The finding, published in the journal Scientific Reports, provides a hint of evidence that humans can use volatile chemicals as signals, the authors argue. While much more data would be needed to support such a speculation, the authors still note that viewership ratings can be useful in judging whether movies are actually funny or exciting.
For the study, researchers connected a proton transfer mass spectrometer (PTR-MS) to the outgoing vents of a theater during 108 screenings of 16 different films, including Friend, The HobbitAnd carry. The PRT-MS measured 100 of the 872 volatile chemicals known to be emitted by humans, with a detection limit of sub-parts per billion.
Looking through the gas profiles of different audiences watching the same movie, the researchers noticed synchronized and reproduced spikes in certain chemicals. For example, the authors noted two peaks of isoprene – an insoluble gas associated with cholesterol synthesis in humans – at specific times during The Hunger Games: Catching fire. The peak moments, the authors report, correspond to “key moments in the film when the heroine’s dress catches fire and when the final battle begins.”
The researchers then went through each film and labeled each scene. The labels include sex, comedy, suspense and mystery. The researchers then analyzed the data with a supercomputer to look for more correlations between scene types and chemical emissions.
The researchers found the strongest chemical links to comedy and suspense/injury scenes. Injury scenes, a subset of stress, were associated with spikes in methanol, acetaldehyde, 2-furanone, and butadiene. “These could be interpreted as an evolutionarily advantageous warning/stand-down signal, if observable by others,” the authors speculate. However, this hypothesis may be evading simpler explanations, such as small physiological responses to different types of stimulation. Either way, the emission patterns could serve as objective measures of film quality, they conclude.
Clarification: This story has been updated to clarify that the authors’ speculation about chemical signaling between humans is not supported by the data presented here.
Scientific Reports2016. DOI: 10.1038/srep25464 (About DOIs).