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How civil engineers change our brains

March 13, 2012

Puzzle: Why do civil engineers build bends into motorways/freeways when there is no geological or geographical need to?

Has it ever occurred to you as you drive across a flat, featureless plain, why the motorway/freeway’s arrow straightness periodically veers into a gentle curve?  Curves cost tens of millions, so if it was to avoid the property of some stubborn small farmer, that was one expensive deal. But engineers have to build these curves, even if there is no protesting property-owner or gaping chasm in their path. Why?

The answer lies in the fragility of our brains, and in particular of a brain system that allows us to concentrate on undemanding, routine activities – like driving across a featureless plain. But you also need it for studying, reading, following a lecture or listening for your flight to be announced at the airport.

The system is called the vigilant attention system, or the sustained attention system, and is controlled by the right half of your brain – particularly outside surface of your right frontal lobe. It is also closely linked to a chemical messenger in the brain called noradrenaline. People with attention deficit hyperactivity disorder have real problems with this type of attention and many of them have chronically low levels of noradrenaline in their brains which makes them restless, sensation seeking, and attracted to alertness-boosting drugs like nicotine.

But what has this got to do with civil engineers? – The critical feature of this attention system is that it is internally driven – ie you keep your mind on the road/book/lecture in spite of the fact that the road/book/lecture has no attention-grabbing features about it. The jargon here is that your attention is endogenously controlled.

Contrast this with situations where your attention is externally controlled – by a really stimulating computer game, by a very exciting or sexy movie or by the narrative tension of some brilliantly-scripted film. Here your attention is in the hands of the director – they have your brain like putty in their hands – and in particular your right hemisphere vigilant attention system. Here our internal control system can have a rest, because it is externally controlled. People with ADHD have much less difficulty attending in this sort of situation – which can be a puzzle for their relatives and even some doctors who can’t understand how they can concentrate for hours on ‘Medal of Honor’ but only for seconds on reading a textbook.

Civil engineers figured this out long before cognitive neuroscientists like me did and began to build bends into roads so that they could externally control the attention of drivers and stop them driving off the road.

I have never been to the Middle East, but I believe that in some desert areas, the roads are built arrow straight for hundreds of miles – and the roadsides are, I am perhaps unreliably told – littered with crashed and burnt out cars and trucks.

So, the next time you drive across a flat plain and find your fingers tightening on the steering wheel to steer round the gentle curve, consider the tens of millions of euro/dollars/yen that have been spent to change the firing of a few million  cells in your brain.

PS If you feel inclined, you can read more about this brain system here:

2 Comments leave one →
  1. brucehood permalink
    March 19, 2012 7:54 pm

    Ah so that explains, the Fall of the Roman Empire. If they had just put some bends in their damn straight roads, they would have lasted for another 500 years.

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