Among adolescents of of low ability and older age, the Flynn Effect has reversed in the US, leading to worsening IQ over time.
With n>10,000 US adolescents, study suggests disparities in cognitive ability may be widening with a positive Flynn Effect for above avg IQ and a negative Flynn effect for below avg IQ (and gifted women "benefiting" the most):
The Matthew Flynn Effect: Flynn Effect (IQ scores > ~3 points/decade) + Matthew Effect (to those who have more shall be given, from those who have not, even what they have will be taken away). New study finds smart getting smarter, dumb getting dumber.
IQ inequality is growing over time in the US, with increases only at the high end
Inequality is getting worse - in intelligence as well as in money
"A negative Flynn Effect for those with low intellectual ability suggests widening disparities in cognitive ability."
Wow. In a large, representative sample, researchers found: • No Flynn Effect overall • A Flynn Effect for the most cognitively able but a negative Flynn Effect for the least • A Flynn Effect for younger teens but a negative Flynn Effect for older ones