Although Dr. Lewis M. Terman set an IQ cutoff of 135 for his famous ‘termite‘ study, scorers above 150 and 180 have also been studied, although not surprisingly the sample sizes are small.
From the Feldman, D. H. study:
Among the subjects in Terman’s five-volume study Genetic Studies of Genius (1925-1959), 26 scored 180 IQ or above (7 women and 19 men). Follow-up studies of the Terman group have been carried out over a 50-year period, the most recent being done in the late 1970s by Robert and Pauline Sears (Sears, 1977; Sears & Barbee, 1978). The “Termites,” as they were called, are now in their seventies. In none of these follow-ups was the group who scored above 180 singled out for comparison with the rest of the sample. In order to make such a comparison for this study, 26 subjects were selected at random from Terman’s original 1,500. The lives of these 15men and 11 women were compared with those of the 26 who had scored 180 or above on the Stanford-Binet. Few formal analyses were made; by and large, impressions are reported from a careful reading of each of the 52 files.
The comparisons made in this article are between two groups of academically talented individuals. It would be a very different thing indeed if we were to compare the above-180 IQ group with a group of average IQ individuals. This is more or less what has been done in the Terman studies for the sample as a whole. The rationale for comparing two groups with high IQ group and an average group. On this basis, the 180 IQ group might reasonably be expected to stand out from the 150 IQ group as dramatically as the comparison of very gifted to average. Is this in fact the case?
Briefly, the answer is yes and no, perhaps more no than yes. As a group, the above-180 IQ sample is distinguishable in certain respects from its somewhat less gifted peers, but the differences are not as pronounced as one might have imagined. Let us consider some of the ways that the two groups of individuals appear to be similar and dissimilar.
However, the author admits the results were somewhat underwhelming, although the highest of scorers were overall successful academically and in professional life:
For the men we have a substantially different story. For both groups there is a consistently high degree of professional achievement, although not without exception. There is a small number of distinguished men in the above-180 IQ group and a larger number of successful, but not outstanding, individuals. For the above-180 IQ group, we find an internationally known academic psychologist, a highly honored landscape architect, a judge, and a promising pollster who took his own life at age 28. For the 150-IQ group there are no exceptional achievers, but most of the subjects have been productive and successful. Two professors, two engineers, two accountants, a physician, a lawyer, an army colonel, several executives, an electronics teacher, a winery owner, and a lemon grower complete the list.
I lol-ed at the lemon grower part.
On the whole, one is left with the feelings that the above-180 IQ subjects were not as remarkable as might have been expected. Without question they have done better than the general population in most major categories and there is some evidence (although not a great deal) that they were more successful in their careers than the 150 IQ group. But, when we recall Terman’s early optimism about his subjects’ potential, and the words of Hollingworth (1942) that “the children who test at above 180 IQ constitute the “top” among colleges graduates,” there is the disappointing sense that they might have done more with their lives.
Part of the reason for the possible disappointment is that the methodology for calculating IQ may have resulted in inflated scores, from the Hollingworth Mega Society link:
I’ve mentioned above the extraordinary stories of extraordinary children like Michael and Maeghan Such children are presumably quite rare, occurring at the one-in-many-million level. But even though Dr. Hollingworth seems to have thought that her children above 180 IQ were very rare, seemingly, they weren’t that rare even in her own time, occurring once in every 10,000-to-25,000 children. It may be that there were children in 1920 who said their first sentence at 6 months, and who began to read at or shortly after 12 months.
Be that as it may, the answer that would help us to decide how much (if any) of the Flynn Effect is a true improvement in intelligence is the frequency of occurrence of today’s children who can do what Leta Hollingworth’s children could do at the ages cited in the case histories below. If 1 in every 1,000 or 1 in every 2,000 of today’s young children rival Dr. Hollingworth’s children above 180 IQ, then perhaps we can entertain the idea that the Flynn Effect is actually a boost in true intelligence.
IQ scores of the past, such as for Terman’s study, unlike today, were calculated based on ‘mental age’, not standard deviation. This meant that a 6-year-old who scored as well a 9-year-old would have an IQ of 150. A child who learns to read at 4 instead of the typical age of 6-7, could imply an IQ of 150. The problem with this methodology are three-fold: on a normal distribution, an IQ above 180, given a mean of 100 and a standard deviation of 15, confers one-in-a-million rarity, but learning to read early or 4-year-old scoring as well as a 7-year-old on an IQ test, although impressive and implies an IQ of 180 in terms of mental age, is not one-in-a-million rarity. Second, mental age conversion fails for adults. Although a 5-year-old reading a 10-year-old level is something that can be quantified, a 20-year-old reading a 40-year-old level is nonsensical. Nowadays, unlike a century ago, due to the Flynn Effect and the abandonment of mental age in favor of Wechsler scales, IQs above 150 are more ‘legit’ and such high scorers seem ‘smarter’ than high scorers of the past, which is probably why child prodigies of today are more successful, especially in STEM fields, than prodigies of a century ago, and possibly explains the somewhat underwhelming results of the Terman study. But it also means, reported IQ scores above 150, if the subject is over 50-year-old or so, are inflated and that the ‘real’ IQ is probably 135 or so. Third, mental age calculations can results in IQs that are nonsensically high; for example, scores above 240 have been reported, although when converted to a deviation-based score implies a 1/trillion rarity.
But also, as to be expected for such high scores, the sample sizes are small. Even if none of Terman’s >150 subjects or Hollingworth’s subjects were enormously successfully academically in terms of producing landmark results, this may be more of a function of the limited sample size than the failure of high IQ to predict success, but also academic success has a subjective and random element to it too. It’s possible for two researchers of equal IQ to know the same stuff, but one of them by pure luck or other factors, is credited for a discovery. And, of course, there is more to life than just academic success.