Is Very High Intelligence More Beneficial than Moderately High Intelligence?

Higher intelligence generally correlates with positive outcomes in education, career, and daily life. However, some researchers propose that beyond a certain point, additional IQ points provide diminishing returns. This concept, known as the threshold hypothesis, suggests that extremely intelligent individuals may not experience significantly better outcomes than those who are merely above average.

Proponents of this idea disagree on where the threshold lies. Gladwell (2008) and Simonton (1976) placed it at IQ 120, suggesting the top 9.2% of the population gains no additional advantages beyond this level. Feldman (1984) set it higher at IQ 150, affecting only 0.04% of people. They also differ on which outcomes are affected—some claim all life domains show this plateau, while others argue it applies only to emotional and educational results but not occupational success. Towers (1987) even suggested exceptionally high IQ (around 170) could harm social functioning and relationships.

Studying the exceptionally intelligent is inherently difficult due to their rarity. Only about 1 in 10,000 people have IQs of 156 or above, and merely 1 in 31,500 reach 160 or higher. The entire United States contains only approximately 10,300 individuals with IQs exceeding 160. Additionally, standard intelligence tests often cannot differentiate among the highly gifted—the popular WAIS-IV, for instance, caps at 145.

Despite these challenges, the best available research refutes the threshold hypothesis. Data from the Study of Mathematically Precocious Youth (SMPY), which includes over 2,300 individuals in the top 1% of IQ, reveals that benefits continue accumulating at higher intelligence levels. Within this elite group, those in the top quarter of the top 1% had dramatically higher odds compared to the bottom quarter: 3.56 times more likely to earn doctorates, 2.31 times more likely to achieve top 5% incomes, 3.01 times more likely to obtain patents, and 4.55 to 4.97 times more likely to publish literary or scholarly works (Lubinski, 2009).

Even at IQ 156 (top 0.01%), the pattern persists—over half earned doctorates compared to 30% of those at IQ 139. These individuals "constitute a precious human-capital resource" as outstanding cultural contributors (Kell, Lubinski, & Benbow, 2013, p. 648).

Other studies confirm these findings. Wai (2014) found the brightest quarter of top-1% teenagers earned doctorates at 1.52 times the rate of the least bright quarter. Coyle (2015) demonstrated that intelligence correlates with college grades across all ability levels with no plateau. Additional research shows progressively higher IQs predict earlier academic development and faster curricular advancement (Ruf, 2005).

Contrary to claims that extreme intelligence creates social difficulties, research finds no evidence of increased problems. Children with IQs above 130 and 144 show no more social or emotional issues than those in the 110-120 range (Guldemond et al., 2007). The theory of "overexcitabilities"—supposedly unique psychological challenges for the highly intelligent—lacks convincing evidence. In fact, high intelligence may protect against certain psychiatric conditions (Savage et al., 2018).

The threshold hypothesis crumbles under scrutiny from large-scale, quality research. Earlier support stemmed from small samples, flawed data, or misinterpretation. The evidence clearly indicates that intelligence benefits never plateau or diminish. However, intelligence alone doesn't guarantee success—interests, work ethic, specific abilities, educational opportunities, and supportive environments all matter. These outcomes remain probabilistic, and exceptional intelligence doesn't guarantee favorable results.





From Chapter 25 of "In the Know: Debunking 35 Myths About Human Intelligence" by Dr. Russell Warne (2020)