"11- and 12-year-old children in year 7 are "now on average between two and three years behind where they were 15 years ago", in terms of cognitive and conceptual development."
And what of the cause?
" I would suggest that the most likely reasons are the lack of experiential play in primary schools, and the growth of a video-game, TV culture. Both take away the kind of hands-on play that allows kids to experience how the world works in practice and to make informed judgments about abstract concepts."
This certainly would make sense if reports that television in particular are linked to poor educational outcomes (1) and 'modest adverse effects' on cognition of TV viewing particularly by the under 3s (2) are true.
It is certainly part of the thesis of Dr Aric Sigman in his new book 'Remotely Controlled' which contains some interesting ideas.
'Children are less able than they used to be' http://education.guardian.co.uk/schools/story/0,,1693061,00.html
1) Association of television viewing during childhood with poor educationalachievement. Hancox RJ, Milne BJ, Poulton R. Arch Pediatr Adolesc Med. 2005 Jul;159(7):614-8.