Found this at Gladwell.com.
Twenty years ago, a political philosopher named James Flynn uncovered a curious fact. Americans – at least, as measured by I.Q. tests – were getting smarter. This fact had been obscured for years, because the people who give I.Q. tests continually recalibrate the scoring system to keep the average at 100. But if you took out the recalibration, Flynn found, I.Q. scores showed a steady upward trajectory, rising by about three points per decade, which means that a person whose I.Q. placed him in the top ten per cent of the American population in 1920 would today fall in the bottom third. Some of that effect, no doubt, is a simple by-product of economic progress: in the surge of prosperity during the middle part of the last century, people in the West became better fed, better educated, and more familiar with things like I.Q. tests. But, even as that wave of change has subsided, test scores have continued to rise – not just in America but all over the developed world. What’s more, the increases have not been confined to children who go to enriched day-care centers and private schools. The middle part of the curve – the people who have supposedly been suffering from a deteriorating public-school system and a steady diet of lowest-common-denominator television and mindless pop music – has increased just as much. What on earth is happening? In the wonderfully entertaining Everything Bad Is Good for You (Riverhead; $23.95), Steven Johnson proposes that what is making us smarter is precisely what we thought was making us dumber: popular culture.