Flynn Effect - Possible End of Progression

Possible End of Progression

See also: Dysgenics and Fertility and intelligence

Jon Martin Sundet and colleagues (2004) examined scores on intelligence tests given to Norwegian conscripts between the 1950s and 2002. They found that the increase of scores of general intelligence stopped after the mid-1990s and declined in numerical reasoning sub-tests.

Teasdale and Owen (2005) examined the results of IQ tests given to Danish male conscripts. Between 1959 and 1979 the gains were 3 points per decade. Between 1979 and 1989 the increase approached 2 IQ points. Between 1989 and 1998 the gain was about 1.3 points. Between 1998 and 2004 IQ declined by about the same amount as it gained between 1989 and 1998. They speculate that "a contributing factor in this recent fall could be a simultaneous decline in proportions of students entering 3-year advanced-level school programs for 16–18 year olds." The same authors in a more comprehensive 2008 study, again on Danish male conscripts, found that there was a 1.5 points increase between 1988 and 1998, but a 1.5 points decrease between 1998 and 2003/2004. A possible contributing factor to the recent decline may be changes in the Danish educational system. Another may the rising proportion of immigrants or their immediate descendants in Denmark. This is supported by data on Danish draftees where first or second generation immigrants with Danish nationality score below average.

In Australia, 6–11 year olds IQ, as measured by the Colored Progressive Matrices, has shown no increase from 1975–2003.

In the United Kingdom, a study by Flynn (2009) found that tests carried out in 1980 and again in 2008 show that the IQ score of an average 14-year-old dropped by more than two points over the period. For the upper half of the results the performance was even worse. Average IQ scores declined by six points. However, children aged between five and 10 saw their IQs increase by up to half a point a year over the three decades. Flynn argues that the abnormal drop in British teenage IQ could be due to youth culture having "stagnated" or even dumbed down. He also states that the youth culture is more oriented towards computer games than towards of reading and holding conversations. Researcher Richard Gray, commenting on the study, also mentions the computer culture diminishing reading books as well as a tendency towards teaching to the test.

Lynn and Harvey have argued that the causes of the above are difficult to interpret since these countries have had significant recent immigration from countries with lower average national IQs. Nevertheless, they expect that similar patterns will occur, or have occurred, first in other developed nations and then in the developing world as there is a limit to how much environmental factors can improve intelligence. Furthermore, during the last century there is a negative correlation between fertility and intelligence. They estimate that there has been a dysgenic decline in the world's genotypic IQ (masked by the Flynn effect for the phenotype) of 0.86 IQ points for the years 1950–2000. A further decline of 1.28 IQ points in the world's genotypic IQ is projected for the years 2000–2050. Similarly but looking at phenotypic IQ, Meisenberg has argued that both higher GDP and IQ independently reduce fertility. The study argues that "at present rates of fertility and mortality and in the absence of changes within countries, the average IQ of the young world population would decline by 1.34 points per decade and the average per capita income would decline by 0.79% per year."

If there have been declines in national IQs this may have causes other than those proposed above. In an essay published online in The Lancet, two researchers have warned that exposure to industrial chemicals may be responsible for a "silent pandemic" of brain development disorders.