Cox-Terman-Merrill IQ scale

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In genius studies, Cox-Terman-Merrill IQ scale refers to []


In 1916, Lewis Terman, in his “The Measurement of Intelligence”, building on the earlier work of Alfred Binet (1905), Henry Goddard (1910), and William Stern (1912), introduced the following IQ scale:[1]

Terman IQ scale (1916) 2.jpg

In 1926, Catherine Cox, Lewis Terman, and Maud Merrill expanded the upper range of Terman’s scale, by ranking the IQs of the top 300 geniuses, from the Cattell 1000, born between 1450 and 1850, calculated IQs up to 225. The following, to exemplify, are their top 20 geniuses according to AI IQ (age 1-16 range IQ) or IQs for “individuals rated on the evidence of their behavior and performance in childhood and early youth” (pg. 47), as opposed to AII IQ (foldout table not available), referring to individuals “in the first period of young manhood”, wherein “C” stands for Catherine Cox, “M” stands for Maud Merrill, and “T” stands for Lewis Terman:[2]

AI IQ top 20 (Cox, 1926).jpg

TCM-Hollingworth-BPT IQ table

The following is a summary of the original 1916 Terman IQ scale, the 1926 Cox extended historical geniuses range IQ scale, along with the late 1930s critical analysis of the former by Leta Hollingworth, as discussed below, and the mean Cox-Platt-Buzan-Thims IQs, which show the "only two" established IQs, historically speaking, according to consensus of the previous century's work on calculating historical IQs of geniuses, that can can be trusted as being semi-accurate estimations, as the future might see things; all other calculations being subject to personal bias and or lack of time-delayed digestion of the work of the genius, which thereby indicates that the exact IQ "number" that seemingly differentiates "genius" from "very superior intelligence" is yet to be determined:[3]

IQ Terman Classification


| Cox-Terman-Merrill Classification


| Hollingworth




225 Goethe (M calculation)
210 Goethe (CTM mean)
205 Leibnitz
200 Grotius and Wolsey
199 Newton
195 Pascal and Sarpi
190 9 geniuses
185 11 geniuses
180 28 geniuses
175 23 geniuses Darwin
170 24 geniuses
165 53 geniuses
160-180 Genius Cutoff Up.png
160 42 geniuses
155 39 geniuses
150 13 geniuses
145 15 geniuses
Above 140 "Near" genius or genius Up.png
140 8 geniuses Up.png
135 8 very superior intelligences
130 Drake and Grant
125 Massena
120-140 Very superior intelligence
110-120 Superior intelligence
90-110 Normal, or average, intelligence


In 1938, Leta Hollingworth, after studying about 20 children she had found that tested in the 180+ range, began to argue, in various publications, that Terman’s childhood tested “IQ of 140” was too low to be the IQ criterion of the “genius” level, in that it engulfed too much of the sum human population for what was a rather rare phenomena, historically speaking; to quote:

“The term ‘genius’ has been use by Terman—and following him by many others—to denote children testing at or above 140 IQ. In the light of the developmental data herein presented, it would appear that the term ‘genius’ is misapplied, unless we wish to define ‘geniuses’ persons who represent approximately the best fourth of all students being graduated from American colleges.”
— Leta Hollingworth (1942), Publication (pg. 247) [4]

This, of course, in history of American education, has resulted in many children being labeled as “geniuses”, when in fact they were not, or did not turn out to be geniuses in adulthood, akin to a form of reverse psychology based on mis-aligned test score definitions. Hollingworth’s view is summarized as follows:

“This text also presented the opportunity for Hollingworth to discuss the definition of genius, upon which—she conceded at the time of the publication—there was still disagreement as to the corresponding IQ score (Hollingworth, 1942). However, she felt that Terman's original estimation of 140 IQ provided too large a population for a phenomenon that was thought to be so rare. Hollingworth and Terman also differed in their perception of genius. Terman's five volumes were titled Genetic Studies of Genius, as he had from the outset labeled children with a qualifying IQ score "geniuses." Hollingworth, however, felt that the term "genius" should only be applied once students had been acknowledged in their fields as top producers. This usually occurred after they had graduated from university. Only those in the top 1% could make the contributions that would rate at the genius level and only after some type of work recognized by experts in the field as exceptional (Hollingworth, 1938). She also highlighted that once children began to near 170 IQ, difficulties were likely to occur as they often were misunderstood and had very few "likeminded" peers. Highly and profoundly gifted children had distinctive social and emotional needs that differed from the average gifted child. She also suggested that emotional education might be even more paramount than pure intellectual training.”
— Jennifer Jolly (2018), A History of American Gifted Education (pg. #)

The exact cutoff for Hollingworth’s IQ definition of “genius”, supposedly, has been stated at 160 to 180 range (as shown above); her unfinished collected works were published posthumously, as Children Above 180 IQ: Stanford-Binet Origin and Development (1942), by her husband.

End matter


  1. Terman, Lewis. (1916). The Measurement of Intelligence: an Explanation of and a Complete Guide for the Use of the Stanford Guide for the Use of the Stanford Revision and Extension of the Binet-Simon Intelligence Scale (classification of intelligence, pg. 79; I.Q., pg. 53, etc.). Houghton Mifflin Co.
  2. (a) Cox, Catharine. (1926). Genetic Studies of Genius. Volume II. The Early Mental Traits of Three Hundred Geniuses (Arc) (pdf) (ratings, pg. viii; Goethe IQ 225, pg. 163). Stanford University Press.
    (b) Cox IQ (subdomain) – Hmolpedia 2020.
  3. Cox IQ (subdomain) – Hmolpedia 2020.
  4. (a) Leta Hollingworth (subdomain) – Hmolpedia 2020.
    (b) Jolly, Jennifer. (2018). A History of American Gifted Education (pg. #). Routledge.

External links

  • IQ scale (subdomain) – Hmolpedia 2020.
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