London, July 28 (IANS): Why is a similar task done efficiently by one person and not-so-well by the other? Scientists now have the answer.

The brains of more intelligent people are capable of solving tasks more efficiently which is why they have superior cognitive faculties - referred to as the “neural efficiency hypothesis” by Swiss researchers.

Although it ceased being a hypothesis quite some time ago, neural efficiency is now being accepted by experts as an undisputed fact.

"When a more and a less intelligent person are given the same task, the more intelligent person requires less cortical activation to solve the task,” said Elsbeth Stern, professor for research on learning and instruction at ETH (Swiss Federal Institute of Technology) in Zurich.

While working with Stern, study co-author Daniela Nussbaumer also found evidence of this effect for the first time in people possessing above-average intelligence for tasks involving what is referred to as working memory.

"We measured the electrical activity in the brains of university students, enabling us to identify differences in brain activity between people with slightly above-average and considerably above-average IQs,” explained Nussbaumer.

The researchers found no differences in brain activity in either group of subjects when they performed very easy or very difficult tasks.

They did, however, see clear differences in the case of moderately difficult tasks.

"All subjects succeeded in solving the moderately difficult tasks but the highly intelligent subjects required fewer resources to do so,” the authors noted.

The study also suggests that it is impossible to "exercise" working memory.

"If subjects practice a certain task for a prolonged period, they improve with time,” the authors noted in a paper appeared in the journal Intelligence.

Stern and her peers also showed that people who have practiced certain tasks do not have any advantage over their unpracticed counterparts when confronted with new, yet similar tasks.