The city as interface (part two)

Posted August 18, 2010 in user centred design  |  No Comments so far

NB: this post is a continuation of “The city as interface (part one)“, published on 6th August 2010

The modern city is a built environment whose purpose isn’t just to house and feed us. It offers us access to both information and capability, and it has evolved ways to help us to understand and navigate its considerable complexity.

In this sense the city is an interface and the people within it, residents and visitors alike, are its users. But the city is not a passive interface. It is a highly responsive one which evolves continually over time.

This constant development is the result of many social and economic factors which I’m not going to explore here. Instead, I’m going to look at two mechanisms that help cities become more effective the more they are used – adaptability and feedback.

Multiple layers of experience

Many modern cities are so complex that even if you spend your whole life in one you’ll never fully understand it. London’s taxi drivers experience physical changes in their brains after spending years memorising its street map, which is just one of the city’s many layers. So what hope is there for the visitors experiencing it for the first time?

The fact is that cities are not allowed to be complicated. If they can’t successfully accommodate outsiders, the outsiders won’t stay, and the city won’t be a city for much longer. The city must therefore be adaptive – it must offer a range of experiences to its users based on the extent of their familiarity and expertise.

A first-time visitor must be able to access the features they need to use without being confused and obstructed by those they don’t. Cities achieve this by using transport networks to negate their geography, or by having certain locals (such as London’s taxi drivers) learn the intricacies so that others don’t have to.

Locals have a better background knowledge of the city so, like power users of a computer system, most things they do become habitual, almost instinctive. But the interface of the city still accommodates their needs. An example of this in many cities is the bus system, which tends to be optimised for locals at the expense of outsiders.

Computer interfaces have similar ways of providing a layered experience to users, and the less specialised the interface the more layers there are. The Nintendo DS has a specific purpose, so its interface has very few layers. More advanced users might configure the clock or change wireless settings, but there’s little else to do apart from load a game:

Systems like Mac OS or Windows are very different. There is a “welcoming” layer aimed at newcomers in which commonly used applications and features are highly visible, and many people use an OS for years without moving on from this layer. But under the surface there are other layers – the registry, the command line, the process list – which can seem intimidating but are essential tools for other users of the system.

Multi-purpose interfaces fail if they intimidate new users with difficult features, and they also fail if they force experienced users to wear kid gloves. A strong interface, like a successful city, will accommodate both user types and all the grey areas in between.

Becoming a part of the interface

When we “use” cities,  they use us too. They incorporate us into the experience offered to other people – we become part of the show. Here’s an example.

One morning last week I was walking to my local tube station. Before long I started to sense that something was wrong. As I got closer to the station this conviction grew, and eventually turned out to be correct: the station was shut and all hell was breaking loose.

How did I know there was a problem? I hadn’t received a text alert or seen any signs. Instead, I’d used something that many city dwellers use all the time, often without knowing – the city’s feedback mechanism.

On that morning I noticed, almost subconsciously, that there were more people than normal on the pavements. Several people apparently dressed for work were walking away from the tube station, or looking confused and directionless. It was subtle but noticeable, and as I noticed it my behaviour changed also. Before long I was part of the feedback mechanism, part of the crowd whose behaviour informed others that the tube station wasn’t working.

The city is full of behavioural patterns that we observe, follow, and unwittingly learn from all the time. Their importance can’t be overstated. Remove the flow of humanity and the city becomes a surreal, frightening place, a sensation that was exploited by the film 28 Days Later.

The inherent eeriness of an empty city

It’s only recently, in the age of social software, that computer interfaces have developed the ability to emulate this sort of feedback mechanism. Older interfaces couldn’t reflect aggregate user behaviour in the experiences offered to individual users. But in today’s online environment things are different.

When you browse Amazon, your navigational choices are used by the system to influence the choices that subsequent visitors will see. When you watch a video on Youtube, you add to its view count in a way that’s visible to others. And if you removed the flow of users from Twitter or Facebook you’d be left with literally nothing at all.

Modern interfaces are starting to use feedback mechanisms similar to those that cities have been using for centuries. Our use of the system affects the system, and affects how others experience it too. The dividing line between the user and the interface becomes a blur.


Analogy is a slippery slope. Successful interactive interfaces may well have lots in common with successful cities, and we may well think of the city as an interface, but the analogy shouldn’t be taken too far. Cities have spatial constraints that computer systems don’t share, and they tend to be the result of long-term evolutionary design processes rather than centrally directed ones.

But even with these differences in mind there’s a lot we can learn from how cities function as interfaces. Cities solve problems that interactive systems have only recently become sophisticated enough to have. If we can understand those problems well enough, the modern city can be a treasure trove of inspiration and insight to designers of future interactive systems.

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