Sixty-eight percent of IQ scores fall between 85 and 114 indicates average intelligence. A score above 130 indicates strong intelligence and a score below 70 may indicate mental retardation. But it turned out that the average intelligence was higher compared to earlier tests.

For one type of intelligence test (Raven’s Progressive Matrices), Flynn was able to compare data over the time span of nearly a century. His conclusion was that a person, who scored in the top 10 percent around a hundred years ago, would now be categorised in the bottom five percent.

That means someone who would be considered bright around a century ago, would now potentially be considered borderline retarded. Overall, test takers in America gained 17 IQ points between 1947 and 2001. And the Flynn effect is accelerating. The annual gain from 1947 through 1972 was 0.31 IQ point, but by the 1990s it had increased to 0.36.

Other tests that measure education-driven skills haven’t shown the same steady gains and neither can this be attributed to improved nutrition, as general improvement in diet levelled off in most industrialised countries shortly after World War II – the same time that the Flynn effect was increasing.

There is debate, however, about whether the rise in IQ scores also corresponds to a rise in intelligence, or simply a rise in skills related to taking IQ tests. The Ravens Test that Flynn looked at (like the majority of IQ tests) consisted of problems involving icons, recognising shapes, correlation between objects and so on.

These aren’t skills accumulated by reading Chaucer and learning to speak Latin. They are, however, similar to those needed while using everyday technological appliances – from VCRs, microwave ovens and thermostats to more recently playing video games or figuring out the iOS7 on an iPhone.

That abstract type of reasoning required is, in many ways, perfect practise for taking IQ tests. Solving a puzzle in Tomb Raider or using spatial geometry in Tetris or completing a mission in Grand Theft Auto requires logic and problem solving that reading a book doesn’t.

According to research for the book IQ and the Wealth of Nations, the top five Countries with the highest IQs are Hong Kong, South Korea, Japan, Taiwan and Singapore. The bottom five comprises Equatorial Guinea, Ethiopia, Sierra Leone, Democratic Republic of the Congo, and Zimbabwe. The countries are at the top are technologically advanced (where video games are also hugely popular) and at the bottom are ones that are far less developed.

The people who dismiss video games often fail to note that, unlike film or television, they are not passive activities. You are constantly being asked to solve puzzles (of various sorts) to progress. Rather than focusing on the occasional dead (digital) person in Tomb Raider and games like it, perhaps we should be noting the problem solving abilities that were required to get that far through the game in the first place. Those skills are the same problems solving abilities by which we measure human intelligence.