It's a big part of the reason I stopped teaching. It's so disappointing to see somebody make such rapid progress, start getting distracted by digital entertainment including social media, and then see all their potential (alongside extensive wasted effort on my part) just flushed down the toilet.
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A sharp but, in my opinion, very related tangent is the Flynn Effect [1]. It was the observation that IQs were increasing over time. IQ tests are always normalized such that the mean is 100 with a standard deviation of about 15. However, Flynn observed that the absolute score of a 100 in e.g. 1950 was higher than it was in 1920 and similarly on forward. Until the 1990s.
Sometime in the 1990s this all changed. In numerous developed nations the Flynn Effect has reversed. Now, for the first time ever, a 100 IQ score would be less today than in e.g. 1985 in many developed nations. And the declines have been quite dramatic reducing on the order of 1-2 points per decade. Keep in mind that 1/15 = 0.07. Somebody who is at the average of 100 would be ahead of about 50% of people. Reduce that by just 1 point he's dropped 0.07 sigmas and is now only ahead of 47% of people. And that's a population level event recurring each and every decade!