In December, I was part of a panel discussion on the ‘Science of Space’ at the MPavilion.

I took part in the discussion alongside two amazing scientists from the The Florey Institute of Neuroscience and Mental Health, Dr Julie Bernhardt and Dr Emma Burrows.

Both Bernhardt and Burrows made reference to the idea of ‘enriching environments’ in relation to the impact of architecture on our brains. The basic principle is that the more stimulating the environment, the more potential for brain development and brain repair for stroke and dementia, among other conditions.

An enriching environment is an environment that provides the opportunity for socialization, physical, sensory and cognitive challenge. With my main area of interest being urban public space, I immediately started to think about the idea of enriching environments in relation to this context, particularly our streets.

Cities are generally places of stimulation, providing a high level of sensory experience, with the level of stimulation increasing as density increases. By density, I mean buildings, people, cultural diversity and difference.

In 1947, the ethologist John B. Calhoun experimented with the impacts of crowding on rats. Calhoun created an environment where rats were given everything they needed except space. The result was an initial growth in population followed by extinction. Calhoun concluded that overcrowding resulted in pathological behaviour, which he later coined a ‘behavioural sink.’ These results were widely assumed to be transferable to humans, painting cities as dangerous habitats. However, there is evidence to suggest otherwise.

Take the slum Dharavi in Mumbai for example, where a million people coexist in around one square kilometre. Notwithstanding some serious issues, including access to fresh water and waste management, you can still find full employment, 100 per cent recycling, vibrancy, innovation and a very strong sense of community.

More recently, city living has also been linked with several mental disorders including schizophrenia and depression. A 2009 meta-analysis by Dutch researchers found that people living in urban environments have a 20 per cent higher risk of developing anxiety disorders, and a 40 per cent higher risk of developing mood disorders. However, there is much evidence to support the many benefits of living in cities, particularly dense, compact cities.

In truth, to date, we know very little about how urbanization and density are changing our brains and our behaviour. We are only really beginning to explore these impacts, but given the rate of urbanization, density and diversity of our cities, such research is critical in understanding how to design cities that provide for our mental and physical health and well-being. This is arguably much more important than most of the factors applied in the numerous liveable city indices that are widely used to rank the quality of life in cities around the world.

Enriching environments and the role of stimulation raises some really interesting questions about what our streets, neighbourhoods, suburbs and the city should look and feel like. Enriching environments are most likely highly subjective in this context.

Consider two distinctly different Melbourne suburbs – Toorak and Brunswick. We might characterize Toorak as an affluent, very clean and well-maintained place. However, to some that creates a very dull, bland and boring environment. On the other hand, Brunswick is home to many who are less affluent. It is not as clean, nor as well-maintained as Toorak but is arguably more colourful, vibrant and exciting.

The urban sociologist Prof. Richard Sennett would probably categorise Brunswick as an ‘open city’ and Toorak a ‘closed city.’ Sennett and his esteemed wife, professor Saskia Sassen, are both concerned about the privatisation and regulation of our cities, particularly our public spaces, which results in (among other things) the exclusion of certain groups, such as the poor, immigrants, and the homeless. It also results in the sanitisation of public spaces and the loss of much of what really stimulates us in cities, namely the unexpected encounters with strangers, others and the traces people leave on the city, such as unapproved street art and installations (to name but a few).

Gentrification also plays a significant role in this respect, although it tends to create exclusive environments, enriching for those that can afford them. There is a real risk of our cities becoming rather bland and dull places, lacking in stimulation.

Some types of stimulation are better than others, and too much of some good types are also bad for us. The question is therefore how to mediate the bad and the excessive. One of the most important ways we can do this is through access to nature. Esteemed British artist Antony Gormley recently noted when commenting on the transformation of London, “human nature only makes sense in relation to nature, feeling the seasons and the elements.” Gormley was stressing the importance of our relationship with the natural world as cities become denser, because density is double-edged, bringing many benefits and potential risks.

In the 1980s, environmental psychologists Rachel and Stephen Kaplan provided a theory for the benefits of exposure to nature called Attention Restoration Theory, which is based on the ability of the natural world to fascinate us in a way that does not require our focused or direct attention. In other words, we can drift off into a dream-like state, consumed by the beauty and fascination of nature. In doing so, we allow our mental capacities to replenish.

To get access to nature, we can do a lot more than provide big parks and gardens, through green rooftops and other means. Critically, we need more ‘green’ on our streets and in our buildings. This is one reason we need bigger outdoor, and possibly indoor, spaces in apartments. It is also why we need more trees on our streets.

In this respect, the City of Melbourne deserves a lot of praise and thanks for their work in this area, which has been winning awards from around the world. However, we can do much more, particularly in terms of mandating more greenery in new buildings of all types. The integration of nature with our cities is therefore fundamental to our psychological and physiological comfort, reducing mental stress, reducing the impacts of the heat island effect and reducing air pollution.

We face two interrelated challenges that are paradoxically at odds with the current transformation of our cities. Firstly, how do we provide enriching urban public spaces without killing them through regulation and privatisation?  Secondly, how do we provide sufficient access to nature to mediate the negative impacts of overstimulation and bad stimulation?

The key will be in tackling both issues at the same time.