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Here's another figure that combines a few authoritative datasets/ meta-analyses about IQ and PISA (scholastic aptitude) scores over time (partly the same as the ones I posted a few days ago). All of these are based on very large samples, so measurement error is very low. What to make of this?

14/9/26, 12:24 pm1 repost2 likes

Sebastiaan Mathôt

@cogsci.nl

14 Sept

I mislabeled the OECD-23 results as Europe in the figure. This group also includes a number of non-European countries, such as Japan and Australia.

Sebastiaan Mathôt

@cogsci.nl

14 Sept

Historically, IQ has increased dramatically, and in some forms this has happened across the world. This is the well-known Flynn effect. When looking at global IQ, this trend seems to continue at least in some places up to around 2010 (and then the data stops).

Sebastiaan Mathôt

@cogsci.nl

14 Sept

However, when looking at (some) EU countries, the trend seems to have reversed, with IQ peaking in the late 90s and declining up to 2010 or so. There appears to be no reliable data after this point. However, European PISA data suggests a continuing decline.

Sebastiaan Mathôt

@cogsci.nl

14 Sept

Of course, PISA tests are not direct IQ tests. However, historically these scores correlate very highly (and can be converted), so PISA scores are a reasonable proxy for IQ.

Sebastiaan Mathôt

@cogsci.nl

14 Sept

Why do I post this? Substantial evidence suggests that cognitive abilities are declining across the board, at least in some parts of the world. If true, this is a worrying trend that could have real consequences. I feel this should not be brushed aside, as often happens. ("It's just …")