The most intelligent 14-year-old in 2008 is now only on a par with the brightest 12-year-old in 1976, according to the findings.

Researchers at King's College, London, asked 800 children aged 13 and 14 to take a series of tests which measured their understanding of abstract scientific concepts such as volume, density, quantity and weight.

The results were compared with a similar exercise in 1976.

In a test known as the pendulum test just over one in ten were found to have reached top grades which demanded a 'higher level of thinking', a significant drop from the 1976 result of one in four.

In a second test, which assessed mathematical thinking skills, one in five youngsters in 1976 had achieved high grades whereas the figure from the most recent study was only one in 20.

But average achievement was found to be similar in teenagers from both generations.

Professor Michael Shayar, who led the study, said: "The pendulum test does not require any knowledge of science at all. It looks at how people can deal with complex information and sort it out for themselves."

He believes that the decline in brainpower has happened over the last ten to 15 years and could be a result of national curriculum targets which drill children for tests as well as changes in children's leisure activities, such as an increase in computer games and television watching.

根据研究发现，２００８年最聪明的十四岁孩子的智力，只相当于１９７６年最聪明的１２岁的孩子。

伦敦皇家大学的研究者请８００名１３至１４岁的孩子，参加了一系列旨在评估他们对抽象科学概念，如体积、密度、数量、和重量的理解能力测试。

其结果与１９７６年与此相似的测试结果相比较。

在被称为摇摆试验的测试中，只有十分之一以上的人达到了需要“高水平思维”的最高级，远远低于１９７６年四分之一的结果。

在第二个评估数学思维能力的测试中，１９７６年有五分之一的孩子达到了高级，而最近的调查数据却只有二十分之一。

不过，研究发现，两代青少年的平均成绩却相似。

领导此次研究的迈克尔·Shayar教授说：“摇摆试验根本不需要任何科学知识。它的目的是看人们是如何处理复杂的信息，并根据自己的需要把信息分类。”

他相信，脑力的衰退是在过去十至十五年内发生的，可能是因为国家课程的目标在于训练孩子们考试的能力，以及孩子们休闲活动的改变，如打电脑游戏和看电视的时间过长而产生的后果。