Are kids not as capable as they used to be?

According to an article in the UK's Guardian newspaper, recent research indicates that kids are developmentally 2-3 years behind where they were only 15 years ago. From the article:

New research funded by the Economic and
Social Research Council (ESRC) and conducted by Michael Shayer, professor of
applied psychology at King's College, University of London, concludes that 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.

"It's a staggering result," admits
Shayer, whose findings will be published next year in the British Journal of
Educational Psychology. "Before the project started, I rather expected to find
that children had improved developmentally. This would have been in line with
the Flynn effect on intelligence tests, which shows that children's IQ levels
improve at such a steady rate that the norm of 100 has to be recalibrated every
15 years or so. But the figures just don't lie. We had a sample of over 10,000
children and the results have been checked, rechecked and peer
reviewed."

This study was only designed to measure progress, and not uncover causes. However, Dr. Shayer offers some thoughts:

"We can speculate," he says, "but there's no
hard evidence. 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 is a potential new factor in the education reform equation: what if the kids just aren't as capable as they used to be?

Parental responsibility has always been the third rail in the education debates - what if this is a parenting issue, assuming Shayer is right about TV and video games being a likely culprit? Who's got the guts to take parents to task, and will parents, who are also affected by our culture of immediate gratification, be willing to take the hard path of turning off the TV and the PlayStation in favor of spending time outdoors?

And how does a need for experiential play align with high-stakes testing starting in the 3rd grade?