Dalla seconda guerra mondiale a fino al 1975, il QI medio è cresciuto in maniera piuttosto rapida. Poi, almeno in alcuni Paesi, l’effetto sembra essersi annullato e la crescita del QI ha cominciato a regredire.
Come mai? In quest’articolo di Slate viene spiegato in quali direzioni va la ricerca e quali ipotesi sono state sollevate.
“It’s wrong to hint that scores on tests of memory and abstract thinking have been falling everywhere, and in a simple way. But at least in certain countries—notably in Northern Europe—the IQ drops seem very real. Using data from Finland, for example, where men are almost always drafted into military service, whereupon they’re tested for intelligence, Dutton showed that scores began to slide in 1997, a trend that has continued ever since. Similar trends have been documented using data from Denmark, Norway, and Sweden. At some point in the mid-1990s, IQ scores in these countries tipped into decay, losing roughly one-fifth to one-quarter of a point per year. While there isn’t any sign of this effect on U.S. test results (a fact that surely bears on our indifference to the topic), researchers have found hints of something similar in Australia, France, Germany and the Netherlands.
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