In effect, the cinema is a small scale analogue of the on-going planetary scale increases in CO 2 in which additional anthropogenic CO 2 sources from fossil fuel usage must equilibrate with the slow uptake rates into the ocean, vegetation and soils 28. This is some 2 to 8 times the current ambient background levels (400 ppm), but well below the European indoor standard limit of 3500 ppm. People exhale air with circa 4% CO 2, so that as the audience arrives, CO 2 levels increase, rapidly at first and then more slowly as the equilibrium value is approached after about ninety minutes, reaching levels between 1000–2400 ppm. 400 ppm) as ambient air is continually drawn through the cinema from outside. Prior to a film starting in the empty cinema, CO 2 approximates to background levels (ca. 1a, large CO 2 peaks can be observed between 26 th and 30 th December, each corresponding to the screening of a particular film. Data was collected at 30 second time resolution and with sub-ppb(10 −9) detection limits to investigate potential causal links between the audiovisual stimuli and audience emitted chemicals.įigure 1 shows sections of the CO 2 data measured in air from the Mainz Cinestar cinema. During the films, audiences were subjected to audiovisual stimuli while outside air was directed into the cinema through floor vents and out through ceiling vents (normal operating practice) and in the outflow, the concentration of over 100 trace gas species was measured using proton transfer reaction mass spectrometry(PTR-MS) and infra-red spectroscopy. To screen groups of people for potential emotion signaling molecules at natural levels we have conducted a largescale study involving more than 9500 cinemagoers who viewed 108 screenings of 16 different films (including comedy, horror and romance, see Table 1a). Generally, studies reported to date have been small in scale (number of people and measurements), subjectively assessed 13, 14 and often with unnaturally high concentrations of bioassays, due to the analytical methods available. Despite reported chemosignal volatiles in human tears affecting testosterone levels 12, armpit and sweat odours interpreted as fear signals 13, 14, 15, sleeping babies responding to lactating breast volatiles 16, 17, 18 and menstrual synchronization 19, no human pheromone (an evolved chemical signal between humans) has been reliably and reproducibly identified 20.
Yet the extent, or even existence of airborne chemical communication between humans remains controversial 10, 11. The atmosphere has been shown to be an effective conduit for chemical communication between plants and plants 7, plants and insects 8, insects and insects 9. Such chemicals may act as signals, eliciting wide ranging responses 5, 6. Such methods can be applied to research fields such as psychology and biology and be valuable to industries such as film making and advertising.Īll living organisms from the smallest plants and bacteria to trees and primates emit chemicals into their local environment 1, 2, 3, 4. These event-type synchronous, broadcasted human chemosignals open the possibility for objective and non-invasive assessment of a human group response to stimuli by continuous measurement of chemicals in air.
Application of scene labels and advanced data mining methods revealed that specific film events, namely “suspense” or “comedy” caused audiences to change their emission of specific chemicals. It was found that many airborne chemicals in cinema air varied distinctively and reproducibly with time for a particular film, even in different screenings to different audiences. In order to determine whether these emissions vary predictably in response to audiovisual stimuli, we have continuously monitored carbon dioxide and over one hundred volatile organic compounds in a cinema. Human beings continuously emit chemicals into the air by breath and through the skin.