Experiment shows best pupils are less able to analyse

The UK's brightest 14-year-olds are less clever than a generation ago, while their classmates of average intellect are more able, a study shows.

Michael Shayer, professor of applied psychology at King's College, University of London, tested the ability of 13- and 14-year-olds to think rationally and logically.

He compared the survey of 800 teenagers to a similar experiment he did in 1976.

His results for one part of the test showed that almost a quarter of 14-year-olds could think analytically in 1976, while just over 10% can now.

In another section, the high-level thinking skills had dropped from a fifth of 14-year-olds to just 5%.

However, average intellect had improved in a generation.

The findings, to be published in the British Journal of Educational Psychology, contradict national exam results which show a year-on-year rise in top grades in tests taken by 14-year-olds and in GCSEs and A-levels.

Shayer said: "Teachers are concentrating on giving the basic skills to more pupils, so the average ability goes up, but they fail to stretch the brightest so the high-end ability falls."

Shayer and his team examined the teenagers' understanding of abstract scientific concepts, such as density, volume and weight.

The students were asked to study a pendulum swinging on a string and investigate what caused it to change speed.

A quarter of pupils gained high marks in this in 1976, while just over one in ten did today.

In another test, pupils were asked to think about what made weights balance on a beam. A fifth gained good marks in this a generation ago, while just one in 20 did so today.

Shayer said his research showed children's responses were becoming quicker, but that they lacked the ability to think "anything but shallowly". "They are not as able to step back from reality and to reason," he said.

Shayer warned that unless the government urgently tackled the decline in higher-level thinking skills, the future supply of scientists would be compromised.

Professor Peter Tymms, director of the Centre for Evaluation and Monitoring at Durham University, said: "Now there's more emphasis on getting their maths right and less emphasis on their thinking skills."

"They were left to play and take objects apart more a generation ago," he said.

This month the education secretary, Ed Balls, scrapped national tests for 14-year-olds, known as Sats. He said a system of internal teacher assessment would be used instead from next year.