PARIS: Humans have an inborn, intuitive grasp of numbers that varies sharply from one person to the next and is closely linked to advanced maths skills, says a study released Sunday.
In experiments with teenagers in the United States, scientists discovered that children whose "approximate number system" (ANS) was highly developed were also good in school-taught mathematics from an early age.
The ability to roughly estimate quantities in the blink of eye – without any training – has also been found in monkeys, rats and four-month-old infants, and probably has deep evolutionary roots, said the authors.
Deep evolutionary roots
"It is difficult to overstate the importance of the 'number sense' for all kinds of animals," said lead researcher Justin Halberda, a cognitive scientist at Johns Hopkins University in Baltimore, Maryland.
"Maximising your search for food, finding a seat on the bus, recognising the difference between a mating call and an alarm call in a particular species of bird by the number of warbles – all of these require the ANS," he explained.
Previous research had shown that an innate sense of numbers is entirely controlled by a non-verbal region of the brain called the intraparietal sulcus. But to do exact arithmetic and precise calculations, humans require language, which is governed by another part of the brain.
Wide variation
Halberda and two colleagues tested this hard-wired ability to judge quantities by showing 64 fourteen-year-olds a series of images containing between 10 and 32 blue or yellow dots.
In some images – flashed for only one-fifth of a second – there were twice as many dots of one colour. In other images, however, the ratio was closer to parity (with, for example, seven yellow dots and eight blue) and thus much harder to discern.
The results showed a wide variation in the capacity to pick the colour with the most dots at least 75 per cent of the time, suggesting that some people are simply much better at such lightning-fast 'guesstimates'.
