Wednesday, March 12, 2008

The Architecture of the Brain

Terminal 2 at Charles de Gaulle Airport. Walking to the gates from security (entering at the left) the large-numbered gates are on the left hand side, small-numbered gates on the right.

Many people who pass through Charles de Gaulle airport find it confounding and very easy to get lost. According to Paris-based neuroscientist Stanislas Dehaene, this may be because of the way our brains are wired. Dehaene studies how humans process numbers, and he has located a particular part of the cerebral cortex where our understanding of number and quantity seem to reside. A recent New Yorker article by Jim Holt explains Dehaene's research.

While the different areas of the brain are tapped for particular tasks, the circuitry is intermingled, making each part responsible for multiple calculations and functions. It appears that our sense of location and place exist in the same area as our sense of numbers. Dehaene made this discovery a few years back during an experiment on number comparison. He noticed that participants responded better to large numbers when they held the response key in their right hand, but they understood small numbers better when they held the response key in their left hand. Interestingly, when the subjects were asked to cross their hands, the effect was reversed. Holt explains:

"The actual hand used to make the response was, it seemed, irrelevant; it was space itself that the subjects unconsciously associated with larger or smaller numbers. Dehaene hypothesizes that the neural circuitry for number and the circuitry for location overlap. He even suspects that this may be why travellers get disoriented entering Terminal 2 of Charles de Gaulle Airport, where small-numbered gates are on the right and large-numbered gates are on the left."

This has launched an industry to see how the architecture of the brain can impact actual architecture—how our relationship with numbers influences our relationship to space.

Dehaene's studies offer other interesting insights into how different cities function. He analyzes what it is about the brain that makes numbers sometimes so easy and sometimes so hard. Our brain, he says, can easily map 1-3, but higher numbers become increasingly fuzzy and require some thought. When numbers are far apart, like 1 and 99, we are more likely to intuitively know the higher values and less likely to be confused than when the numbers are close, like 7 and 8. More, our very language and how we represent numbers impact our capacity to do math. "The fundamental problem with learning mathematics is that while the number sense may be genetic, exact calculation requires cultural tools—symbols and algorithms..."

Languages like English and French are more cumbersome than the linear and efficient Cantonese. In French, for example, numbers use a confounding base of twenty, so the word for 99 is quatre-vingt-dix-neuf, literally "four twenty ten nine." Chinese is much simpler and the numbers are more succinct. The average French and American four year old child might be able to count as high as 15, a Chinese child can easily count to 40. And as adults, they can hold more numbers in their head at one time. It would seem, then, that the architecture of the brain and an understanding of how we process numbers via language may also have an effect on the economic development of cities in a global economy.