Chemistry Can Reveal Your Emotions at the Movies

By Danielle Ferrante

A recent study has established a link between a movie scene’s emotional content and the chemicals people exhale as they watch it, giving the phrase “suspense is in the air” new meaning.

The Experiment 

Jonathan Williams is an atmospheric chemist at the Max Planck Institute for Chemistry in Mainz, Germany. His interest in measuring the levels of gases in the air started with his experiment at a soccer stadium in Mainz. Williams wanted to see if the fans’ breath would affect the levels of greenhouse gases in the air. The answer was no, because his findings yielded results on a very small scale — but he did notice that carbon dioxide levels increased when the fans cheered excitedly. This prompted Williams to investigate further in a more controlled environment: a movie theater.

More than 9,500 people viewed 108 screenings of 16 movies from different genres, scenes from each of which were assigned a label based on the average rating of 10 volunteers. The labels consisted of three parts: a general term such as “comedy” or “romantic;” a second set that was more specific and referred directly to the scene’s content such as “laughter” or “injury;” and an emotional assessment scheme that used two separate five-point scales, one ranging from happy to sad and the other from excited to calm. Each scene was assigned a label only when two thirds of the volunteers agreed.

During the movie the doors were closed to allow for a controlled circulation of air, which was measured for volatile organic compounds (VOCs) by instruments located outside of the room. The instruments captured those compounds then accelerated them with an electric field to determine what molecules they were made up of as well as how much of each molecule they contained.

The Results

Williams and his team found that certain scenes, primarily those that had people laughing or on the edge of their seats, produced the highest amounts of carbon dioxide and isoprene. Isoprene is the most abundant hydrocarbon measurable in the breath of humans. They attributed this spike to certain physical reactions such as increased pulse and breathing or tense muscle movements.

All living organisms, no matter how small, emit chemicals into the environment, and understanding how these chemicals interact can provide huge insights into the world around us. Going forward, Williams believes exhaled air measurements could allow scientists to investigate human metabolism in greater detail and even allow marketers to quickly measure how a group of people feel about their products.