Take my breath away: analysis of the air exhaled by a cinema audience reveals their emotional responses

31 August 2016

In this month’s Physics World, science writer Stephen Ornes explains how compounds in the breath exhaled by a cinema audience reveal their reactions throughout a film.

Physics World September 2016

Can a film truly be breathtaking? Understanding a single person’s lifestyle, activity and health by analysing the contents of their breath is nothing new, but now research has shown it is possible to decipher the emotional responses of a whole crowd of people, all at the same time, simply by studying what compounds they exhale.

Researchers from the Max Planck Institute for Chemistry in Mainz and the Johannes Gutenberg University of Mainz, both in Germany, studied around 9,500 moviegoers as they watched films such as The Hunger Games: Catching Fire and The Hobbit: Desolation of Smaug and then monitored the concentration and type of the compounds they released into the air.

Devices placed in the outgoing ceiling ducts of a cinema screening room measured molecules in the air, known as volatile organic compounds (VOCs), exhaled by the audience. With one human breath containing more than 200 VOCs, many of which are generated by living cells and metabolic processes in the body, the compounds can reveal a lot about the biological activity of someone, including their emotive responses.

Joachim Pleil, an analytical chemist with the US Environmental Protection Agency at Research Triangle Park in North Carolina, US, and editor-in-chief of the Journal of Breath Research, explains that usually people don’t even think that the air we exhale could provide such a valuable biochemical insight. “The breath is basically garbage,” says Joachim Pleil. “You breathe it out, [and then] you ignore it.”

The researchers were able to spot patterns of certain concentrations of VOCs exhaled that correlated to specific scenes in the movies, including the moment Katniss’s dress catches fire in front of all of Panem before she re-enters the Hunger Games. They were even able to work backwards from the breath readings and predict when scenes of suspense or comedy had occurred; this means their technique is potentially a useful tool for reading people’s emotions.

Outside the world of cinema, relating what we exhale to how we feel could be used in the future for health and threat assessments, marketing or even for lie detection tests.

“This could be a valuable resource for trying to deduce what people think without giving them the opportunity to lie about it,” says Pleil. “There is huge potential for discovery within crowd breath research.”

Also in this issue:

  • Features: Crystallography without crystals – using free-electron lasers to study structure
  • Lateral Thoughts: School experience – meet the physics teacher who transitioned from male to female
  • Features: Census of the cosmos – how Gaia will revolutionize astronomical measurement

Access the September issue digitally now

Also new this month: Special report on China

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