Tension in the (cinema) air

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No doubt you are familiar with the situation: you are enjoying an action thriller at the cinema. On screen the hero is fighting for his life. You are on the edge of your seat, following the action with bated breath and gripping the armrests of your seat. What you cannot see and probably do not even realise is that you are breathing differently than normal – taking somewhat shorter and flatter breaths. Your pulse has also accelerated. And most of your fellow cinema-goers are likely experiencing just the same thing. As a result, the air in the entire cinema theatre changes during this scene: because the audience is exhaling more, the levels of carbon dioxide and other chemical compounds in the room rise.

Exhaled air tells us a lot about the emotions in the theatre

Tension in the cinema air

This is true not only of this particular film sequence, but also of the entire film. Depending on whether they are exciting, funny, sad or boring, film scenes produce a characteristic pattern in the exhaled air – meaning that each film has its very own “air texture”. This is what researchers at the Max Planck Institute for Chemistry and Johannes Gutenberg University Mainz have discovered. Perhaps most spectacularly, the researchers do not need to see the film or the facial expressions of the audience to work out whether the audience is gripped by a particular scene or not – they simply analyse the exhaled air and can immediately tell which emotions the scene is currently triggering in the audience.

How do researchers analyse air in the cinema?

So how did the researchers come up with this extraordinary finding? In a cinema in Mainz, the capital of the state of Rhineland-Palatinate, they attached a tube to the ventilation system. The air extracted from the cinema was routed via the tube to a mass spectrometer. At intervals of 30 seconds, the instrument analysed the air while different films were being screened. Different genres were covered: comedies such as “The Secret Life of Walter Mitty” and “Buddy”, action films like “The Hobbit” and the science fiction thriller “The Hunger Games – Mockingjay 2”. The Institute of Computer Science at Mainz University assisted the Max Planck researchers with collecting and analysing the data.

A lot of tension in the air during “Mockingjay 2”

The chemical signature was particularly striking during “The Hunger Games”. “During the scene where the heroine is fighting for her life, the levels of carbon dioxide and isoprene in the air always rose sharply”, explains Professor Jonathan Williams, atmospheric chemist and group leader at the Max Planck Institute for Chemistry. Besides carbon dioxide, humans normally breathe out more than 800 other chemical compounds, among them isoprene. “Other compounds also increase during this kind of scene”, says Professor Williams.

Why is the cinema project also of interest in other areas?

The research project is about more than just cinema air as far as the atmospheric chemist is concerned. “In my research work I want to find out whether human breathing has any influence on the Earth’s environment and climate – as industry does, for example.” To do so, it is important to understand which chemical compounds are present in our exhaled air, and how they are influenced. “On the basis of our research findings so far, we can state clearly that our breath has no impact on the environment or climate”, says Williams. His research on cinema air is also of interest for instance to psychologists and the advertising industry, as its findings allow quick and objective measurements of how emotional stimuli affect an entire group of people without the need to conduct lengthy surveys.