> Focusing on one part of the IQ test, the Raven's Progressive Matrices, they found that on average intelligence has risen the equivalent of 20 IQ points since 1950. IQ tests are designed to ensure that the average result is always 100, so this is a significant jump.<p>The problem is, that's about the <i>only</i> part that has risen. The limited number of subtests showing the gains has long been one of the big question marks about how the Flynn effect could possibly be about the underlying intelligence rather than an artifact (<a href="https://en.wikipedia.org/wiki/Flynn_effect" rel="nofollow">https://en.wikipedia.org/wiki/Flynn_effect</a>).<p>> This is a puzzle not just for the US, but for all countries demonstrating the Flynn Effect. "Does it make sense," Flynn wrote in one paper, "to assume that at one time almost 40% of Dutch men lacked the capacity to understand soccer, their most favoured national sport?"<p>This sort of point comes up often, but it's not a good point to make. The people discussing IQ tests typically have lived in a tight bubble their entire lives and have not meaningfully interacted with the general population. They typically have even less interaction with the populations of poor countries who might be comparable to long ago. For example, just today I was reading a Wired article which remarks offhand that "In some areas of the country, up to 40 percent of children under 5 are affected. The effects are mental as well as physical. A 2008 study by the National Intelligence Council found that a quarter of North Korean military conscripts are disqualified for cognitive disabilities". Flynn asks whether it's possible for a quarter of Dutch men at some point to not be able to follow soccer well; I ask whether it's possible for a quarter of North Korean men to be rejected by the notoriously voracious NK military because they are too stupid or mentally broken. The latter seems to be true, however...