Outliers: The Story of Success · chapter 3 · id outliers-c3-05-the-threshold-theory-of-iq----
“The threshold theory of IQ -- that above ~120, additional IQ points do not predict additional real-world success -- has been challenged by the Study of Mathematically Precocious Youth (SMPY), which found that even within the top 1%, higher ability predicted greater achievement.”
holdsconfidence: high⚠ extracted by pipeline, re-audit pending
Receipts
Scientific American: How to Raise a Genius (SMPY overview)source alive
The SMPY study found that even among the top 1% of ability, those in the top 0.01% were far more likely to earn doctorates, patents, and high-level academic positions than those merely in the top 1%.
Warne (2019), An Evaluation (and Vindication?) of Lewis Terman, Gifted Child Quarterlypaywalled — manual check queued
The idea that IQ above a threshold of around 120 ceases to matter is not supported by more recent longitudinal data. The SMPY data show linear predictive value continuing well beyond IQ 130.
This claim is a stable, citable object. If you can falsify a verdict, tell us — corrections are loud here.