The Flynn Effect

Throughout the twentieth century, average scores on standardised intelligence tests rose steadily and substantially across the industrialised world, a phenomenon named after the political scientist James Flynn, who documented it with painstaking thoroughness. In country after country, each successive generation outperformed its predecessors, so much so that a person of merely average intelligence by the standards of a century ago would, if measured against today's benchmarks, appear conspicuously below par. The gains were largest not on tests of accumulated knowledge or vocabulary but on abstract, non-verbal puzzles designed to gauge reasoning stripped of cultural content. Because genes cannot change appreciably over three or four generations, the cause of this dramatic climb must （ 1 ） lie somewhere in the environment rather than in our biological inheritance. Something about the modern world, in other words, has been steadily reshaping the very way we think, and the tests were quietly registering that transformation without anyone at first fully appreciating its profound significance.

What, then, might account for it? Flynn himself favoured a subtle explanation rooted in habits of mind. Modern life, he argued, immerses us from childhood in abstraction and classification—we are ceaselessly asked to sort, to hypothesise, to reason about categories and symbols rather than concrete objects. A farmer of 1900 asked what a dog and a rabbit have in common might reply that one hunts the other; a schoolchild today will answer that both are animals. The second response, more abstract and taxonomic, is precisely what intelligence tests reward. On this view, （ 2 ）, our ancestors having simply worn different mental spectacles suited to a more practical and concrete existence. They were not less capable of solving the problems that confronted them; they had merely been trained by circumstance to approach the world through the lens of utility rather than abstraction, and the modern test happens to prize the latter cast of mind above the former, quietly rewarding those who have been schooled in it.

Intriguingly, the effect appears to have stalled, and in several affluent nations it has even gone into reverse in recent decades. Whether this represents a genuine decline in cognitive capacity or merely the exhaustion of the particular gains that modernity once conferred remains hotly contested. Some blame changes in schooling or the fragmenting effects of digital media; others suspect that the earlier rise was always destined to plateau once societies became thoroughly saturated with abstract thinking. Either way, the reversal serves as a useful reminder that the Flynn effect was never evidence that human beings are （ 3 ）; it measured, from the very beginning, a shifting relationship between minds and the particular demands that a given environment happens to place upon them. To mistake that shifting relationship for a straightforward change in raw intellectual horsepower is to misread the whole phenomenon entirely, and the recent plateau, whatever its ultimate cause, only underscores how contingent the earlier gains always were.