Friday, 20 January 2006

Brains, Geometry, and Justice

From Reuters :
Amazonian hunter-gatherers who lack written language and who have never seen a math book score highly on basic tests of geometric concepts, researchers said on Thursday in a study that suggests geometry may be hard-wired into the brain.

Adults and children alike showed a clear grasp of concepts such as where the center of a circle is and the logical extension of a straight line, the researchers report in this week's issue of the journal Science.

Stanislas Dehaene of the College de France in Paris and colleagues tested 14 children and 30 adults of an Amazonian group called the Munduruku, and compared their findings to tests of U.S. adults and children.

"Munduruku children and adults spontaneously made use of basic geometric concepts such as points, lines, parallelism, or right angles to detect intruders in simple pictures, and they used distance, angle, and sense relationships in geometrical maps to locate hidden objects," they wrote.

"Our results provide evidence for geometrical intuitions in the absence of schooling, experience with graphic symbols or maps, or a rich language of geometrical terms."

Geometry is an ancient field and Dehaene's team postulated that it may spring from innate abilities.
"The spontaneous understanding of geometrical concepts and maps by this remote human community provides evidence that core geometrical knowledge, like basic arithmetic, is a universal constituent of the human mind," they concluded.

And from the Pretoria News :
Fairness, empathy and retribution are fundamental drivers of society, helping to shape laws, the judicial systems to carry them out and also individual relationships.

But where do these powerful forces come from?

Neuroscientists at University College London believe they have found evidence in the brain which helps answer this question - and may also explain a distinction between the sexes when it comes to the business of punishment.

Men, they believe, are likely to take pleasure when they see someone punished for an unfair act, but women are likely to feel badly for the culprit.

In a clever two-phase experiment, the researchers recruited 32 male and female volunteers, as well as four others who were undercover actors hired to play the role of volunteers.

In the first part of the experiment, the group played a game of mutual investment in which they had to give money to one of their number. The recipient could decide for himself how much to give back from the profits.

He or she could hand back up to triple the investment, but at little reward to himself; or he could hand back little or nothing, thus maximising his own gains but at the investor's cost.

One actor was cast in a generous role, always giving lots of money back to his partners, while another actor was cast as a mean person, giving back little and sometimes nothing at all.

Body language by the volunteers, confirmed later in questionnaires, showed that they did not like the actors who had cheated on them. "Fair" players, in contrast, were rated as more agreeable, more likeable and, remarkably, more attractive.

In the second phase, the same volunteers were each placed in a magnetic resonance imaging scanner, a device which shows blood flows within the brain.

The volunteer was then given a demonstration of a mild shock - the equivalent of a short beesting - and then watched as the actors, standing next to the scanner, got the same painful treatment. When a "fair" actor received a shock, the scanner showed empathy among all the volunteers.

In males and females alike, the images showed activation of the anterior insula/fronto-insular cortex and anterior cingulate cortex. Previous research has showed that these parts of the brain cause the feeling of distress when one sees someone else in pain.

When an "unfair" actor got a shock, the anterior insula/fronto-insular cortex and anterior cingulate cortex lit up again among most female volunteers.

But in men, these empathic areas showed no increase in activity. What was activated in a big way, though, was the nucleus accumbens, the part of the brain associated with the satisfaction of reward. This activation was not seen in most female volunteers.

The study appears in the British science weekly Nature. Author Tania Singer said the results showed that fairness in social situations "shapes the nature of the emotional link we have to other people".

Singer said: "We empathise with others if they co-operate and act fairly. But in contrast, selfish and unfair behaviour compromises this empathic link."

These fundamental responses at individual level have played a key role in social evolution, believed Singer. They would explain for instance why communities everywhere draw up laws or codes to punish or sideline those who cheat and freeload on the majority.

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