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Vintage etching of phrenological diagram with definitions of the various areas of the human skull. (Cinders McLeod/Photo Illustration)
Vintage etching of phrenological diagram with definitions of the various areas of the human skull. (Cinders McLeod/Photo Illustration)

Is city living harming your brain? Add to ...

Human brains like to be busy and are designed to be attentive to the slightest change – which makes them a worthy adversary for the challenges posed by the modern city.

That contest is increasingly urgent, as the process of urbanization kickstarted by the Industrial Revolution becomes the global norm. Studies say five million new people migrate or are born into cities each month in Africa, Asia and the Middle East. A dozen years from now, 60 per cent of the world will be urban; by 2100, cities will host three-quarters of humanity.

And as we cluster, the ancient animal brain we’re born with has to contend with an urban norm where the rapidity of change could become overwhelming.

“Biological evolution is slow,” says Jay Pratt, professor of psychology at the University of Toronto. “If you look at the acceleration of human cultural evolution, moving from villages to towns to cities, it’s happened so much faster than any biological systems with our lifespan could keep up with.”

Cities fascinate cognitive scientists because they constantly test our neurological range: There’s no better place to entice, stimulate and distract the wandering mind.

The urban form is a metaphor for the mind – an interdependent network that has to make order out of a chaotic flow of non-stop sensory information.

“There’s a tremendous flexibility and plasticity in the brain,” says Prof. Pratt.

One of the most striking examples was demonstrated in a brain-scan study of London cab drivers by researchers at the city’s University College: They were shown to have an enlarged posterior hippocampus, the part of the brain associated with navigation, presumably because of the advanced mental mapping required by their job.

Since the hippocampus seemed to grow over a cab-driver’s career, this appears to be the brain adapting, not just the job attracting people with suitable skills.

That ability to extend memory and spatial processing is encouraging. But London cabbies are also clearly a special case. Memory is a very selective and specific component of experience.

Colin MacLeod, professor of psychology at University of Waterloo, points out the difference between driving your own car to a restaurant in a new part of town and taking a cab.

“If another person is driving,” Prof. MacLeod says, “the next time you go to the same place, you may find you don’t have a clue how to get there. Presumably you weren’t encoding the relevant information – you weren’t paying attention.”

Yet attentiveness has a complicated relationship with memory. While the brain can’t store all of the city’s potential information at the level of instant accessibility, we realize as we navigate neighbourhoods that we’ve held onto knowledge we didn’t realize we had – the location of a dry cleaner en route to work, the eerie feeling that a certain street is coming up on the right.

“There are arguments in cognitive literature that we encode sequence information virtually for free – that it’s almost automatic even if it’s of no immediate use to you,” says Prof. MacLeod.

The mental Goldilocks dilemma: Too little stimulus or too much?

In this sense, our brains are hungry for what a city provides. “Humans enjoy being engaged,” says Prof. Pratt. “We don’t like living in sparse environments.”

A straight, flat, empty path in some rural Arcadia frustrates our state of vigilance much more than a busy city intersection – it’s hard to drift off in Times Square, whatever its other problems. But cities also impose tradeoffs between attentional capture and what psychologists call volitional control.

Our minds are remarkably good at driving a car through a complex urban intersection, carrying out a goal. Yet add a flashy advertising display by the side of a high-traffic street and the brilliant brain instinctively gets suckered in by the flickering brightness: For one dangerous moment, you look away.

In 2011, according to the U.S. National Highway Transportation Safety Board, 3,331 people in the United States were killed in crashes involving a distracted driver. Researchers at Carnegie Mellon found that the brain activity associated with driving is reduced by 37 per cent when you’re using a cellphone.

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