ID’ing movies by fingerprinting the breath for isoprene

16.36, Tuesday 15 Sep 2020 Link to this post

I wonder what gaseous social cues we’re missing, working remotely.

Like, there’s that paper from 2016 about isoprene emissions in human breath…

First, attach a mass spectrometer to the outflow vent of a movie theatre. (They used a theatre for this experiment because it’s a closed box with lots of people in it, amplifying the signal. A good controlled environment.) Then measure the gas quantities every 30 seconds. And:

In Hunger Games: Catching Fire, for example, during the “suspense” scenes–when Jennifer Lawrence was in particular danger–the carbon dioxide, acetone, and isoprene levels in the theater air predictably increased.

Check out the graphs in this other article, which continues: Nearly identical peak-trough-peak patterns occurred during all four screenings of the film in December 2013, allowing the researchers to blindly identify the film just by looking at its unique, air-based fingerprint.

RELATED: you can also tell what someone’s watching by looking at the electricity consumption of the TV. Multimedia Content Identification Through Smart Meter Power Usage Profiles (2012, pdf) shows that if you measure power draw through a smart meter, twice a second, the fingerprint can identify the movie.

Now, it’s not clear whether isoprene changes are signals to one another, or simply byproducts of emotion-based reactions.

But, given an available signal, it would be crazy of the human body to not take it into account.

And if isoprene, then what else? Oxytocin has an effect when delivered into the nose - is it also exhaled, and so passed from one person to another? And other gases in the breath?


Non-verbal, non-visual coordination of small groups, carried in the breath.

The “energy in the room” will be dominated by those who project their breath more – i.e. those who look up and speak the most.

(That’s assuming that gas exhalation levels are equal between people. Given my hunch that charisma is physiological, maybe naturally dominant, charismatic people are simply isoprene super-emitters?)

Does a room carry the emotional memory of the people who were last in it? For how long? Does a sofa absorb isoprene and outgas it slowly over a period of weeks?

Are consensus, compromising political decisions better made in person or over gas-shielding video calls?

Is it possible to carry these group-coordination signals over the internet? Perhaps not as gas… but how about a tiny mass spectrometer next to my laptop mic as an isoprene sensor and, at the other end, mixing tension-inducing infrasound into the audio channel?

I wonder how a gas-sensitive alien would see the world.

Would lying, or broaching a difficult topic, look like a person blowing up a balloon? Would they see a group as a struggle between different coloured gases, slowly coming to an agreement – or, in a different group, fluctuating between different modes?

Like fireflies synchronising. (Could we think of movies as artificial synchronisers, isoprene metronomes for the group? What is we had 45 minute isoprene metronomes for teams, programmable for different types of meetings?)

Perhaps, through the alien, we’d discover that dogs remove isoprene from the air, but don’t emit it, or something like that. The alien would call pets “isoprene sinks,” and they would see them as functioning like the control rods in nuclear reactors that soak up the neutrons.

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