Gifted Issues Discussion homepage Forums GT Research genetic basis for intelligence

Steve Hsu is a physics professor who also does research on intelligence. Below are some quotes from slides of a presentation he gave.

http://duende.uoregon.edu/~hsu/talks/g_colloquium.pdf
Investigating the genetic basis for intelligence
and other quantitative traits
Steve Hsu
University of Oregon and BGI

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General factor of intelligence

SAT, GRE heavily g-loaded: high correlation with g or IQ;
”SAT is an IQ test”
IQ: mean 100, SD 15 (normally distributed)
SAT (M+V): mean 1000, SD  200 (1995 ”recentering”)

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The far tail

Roe study (1950’s): 64 randomly selected eminent scientists had
IQs much higher than the general population of science PhDs.
Almost all of the eminent scientists in the sample scored above
+(3-4) SD in at least one of M / V categories.
Mean score in both categories was roughly +4 SD.
Average for science PhDs around +2 SD, so eminent group
highly atypical among scientists.
Positive returns to IQ > +2 SD in scientific research?

[The cited study is from the book "The Making of a Scientist" by Anne Roe]

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Your kids and regression

Assuming parental midpoint of n SD above the population
average, the kids’ IQ will be normally distributed about a mean
which is around +.6n with residual SD of about 13 points. (The
.6 could actually be anywhere in the range (.5, .7), but the SD
doesn’t vary much from choice of empirical inputs.)
So, e.g., for n = 4 (parental midpoint of 160 – very smart
parents!), the mean for the kids would be 136 with only a few
percent chance of any kid to surpass 160 (requires  2 SD
fluctuation). For n = 3 (parental midpoint of 145) the mean for
the kids would be 127 and the probability of exceeding 145 less
than 10 percent.