In the Mood

A new way to map human cities.

Cities aren't just buildings, sidewalks, buses, and the odd pigeon. They're masses of people--and so, complex cauldrons of emotion. Chart those emotional currents, and you better understand the city.

Christian Nold, an artist and lecturer at the University College London in the UK, has embraced that notion in its most literal sense. His Bio Mapping project outfits people with technology that tracks their moods as they stroll city streets. The resulting maps could encourage community discussion of regeneration, crime, pollution, and noise.

"It's a participatory process of making sense of the neighborhood," says Nold. Here's how it works: Each person is fitted with a rig that tracks galvanic responses via the skin's perspiration, just like a lie detector. Participants wear two finger sensors like thimbles over their index and middle fingers; a wire connects the cuffs to a handheld electronic device carried in a shoulder bag.

Participants also carry GPS devices so they can be tracked as they wander through a neighborhood. After an hour, Nold downloads the data and uses software he wrote to overlay the emotions onto a Google Earth map. With the participants, he writes captions explaining the mood swings. (Typical: "Scary area," and "argument with Mum.") The resulting map for Greenwich, England, available at, is color-coded by relative arousal levels.

So far, Nold has recruited almost 600 people in more than 15 cities to participate. He says he often records heightened arousal at traffic crossings. A decision to go left or right causes some anxiety. And he sees spikes where people turn corners. "Walk around corners and new vistas open up," he says.

It's not clear if the system picks up the embarrassment that comes from walking around with goofy-looking thimbles on your fingers.

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