The rate of increase varies between nations, but on average, IQ scores have risen by three points per decade. But in Britain, research has found a reversal of this trend. This has also been the case in other nations, including Norway and Denmark (research is not extensive, but the implication is that declines may be occurring more widely).
A study in 2009 led by James Flynn himself and published in Economics & Human Biology compared IQ scores obtained by British teenagers in 1980 and 2008, using the same test. The average had declined by two points on average, but by as much as six points among teenagers in the top half of the IQ scale, a fall that wiped out the previous two decades of gains in that group. This added weight to a 2005 study on a sample of 500,000 young Danish men, tested between 1959 and 2004, showing that performance peaked in the late 1990s but then declined to pre-1991 levels. These findings conform with a pattern suggesting that the rise in IQ is slowing, and in some cases, going into reverse.
Scott Adams proposes a new measure of intelligence that takes into account the internet:
Now suppose you compare two people who have the same I.Q. scores, and both have blazing fast Internet connections, but one person is great at searching for information on the Internet, and interpreting it, and the other isn't so good. Now which of the two people is smarter? I would argue that the person who has the better Internet skills is effectively smarter, and possibly by a wide margin. Internet access means nothing if you don't know how to use it.