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.

根據研究發現，２００８年最聰明的十四歲孩子的智力，只相當于１９７６年最聰明的１２歲的孩子。

倫敦皇家大學的研究者請８００名１３至１４歲的孩子，參加了一系列旨在評估他們對抽象科學概念，如體積、密度、數量、和重量的理解能力測試。

其結果與１９７６年與此相似的測試結果相比較。

在被稱為搖擺試驗的測試中，只有十分之一以上的人達到了需要“高水平思維”的最高級，遠遠低于１９７６年四分之一的結果。

在第二個評估數學思維能力的測試中，１９７６年有五分之一的孩子達到了高級，而最近的調查數據卻只有二十分之一。

不過，研究發現，兩代青少年的平均成績卻相似。

領導此次研究的邁克爾·Shayar教授說：“搖擺試驗根本不需要任何科學知識。它的目的是看人們是如何處理復雜的信息，并根據自己的需要把信息分類。”

他相信，腦力的衰退是在過去十至十五年內發生的，可能是因為國家課程的目標在于訓練孩子們考試的能力，以及孩子們休閑活動的改變，如打電腦游戲和看電視的時間過長而產生的后果。