“The inequality that matters,” as they used to say:
In a large US-representative adolescent sample, a Flynn Effect was found for IQs ≥ 130, and a negative effect for IQs ≤ 70
IQ changes also differed substantially by age group
A negative Flynn Effect for those with low intellectual ability suggests widening disparities in cognitive ability
Findings challenge the practice of generalizing IQ trends based on data from non-representative samples
So maybe yes — beware!