Intellectual Outliers: Are There Sex Differences, and Are the Smart
Getting Smarter?,” in Current Directions of Psychological
Science by a trio of Duke University researchers looks at what
is happening to IQ and math ability scores at the highest end of
the IQ distribution – the top 5 and to 0.01 percent, respectively.
About three decades ago, New Zealand political scientist James
Flynn found that average IQ scores were increasing at a rate of
0.33 points per year. The Duke researchers find that IQ scores at
the high end are basically increasing in line with the overall
general trend.The researchers also wanted to see if there were sex differences
in math and verbal scores. An earlier study that looked at the
students who scored in the top 0.01 percent on SAT-Math found the
male-to-female ratio was 13.5 to 1. Their data finds that that
ratio shrank to 4 to 1 and has remained more or less stable for the
past two decades. They conclude:
The fact that we continue to find sex differences in math
ability within the very smartest group means that sex differences
in math ability are likely part of the explanation for female
underrepresentation in high-level math and science careers.
They stress that math ability is a small part of the
explanation. Looking again at the top 0.01 percent on the verbal
tests they find:
These ratios primarily favored females, ranging between one and
two females for every male, and like the gender ratios for math
ability scores, they also appear to have been stable across
With regard to overall IQ score trends in the top of the
distribution, they find:
Using multiple measures from the SAT, ACT, and EXPLORE tests, we
examined whether the Flynn effect occurred for the intellectual
outliers (i.e., the top 5% of scorers). Overall, the effect
appeared to be concentrated on the measures of math (or nonverbal)
ability, with small gains or no gains on the other measures. The
gains on these measures of math ability (amounting to an increase
of 0.33 IQ points per year) are similar to the average rate of gain
found in studies focusing on the general distribution; therefore,
this right-tail finding links directly with the broader literature
on the general population….
These findings demonstrate for the first time that scores among
the entire distribution (including the right tail) have risen at a
relatively constant rate. The Flynn effect may also explain why an
increased number of gifted students has been identified in recent
years: Gifted programs often have cutoff scores that do not change
over time, which may correspondingly lead to a higher proportion of
students attaining that cutoff score.
What is boosting IQ scores among the smartest? The Duke
We think our findings suggest that enhanced cognitive
stimulation may play a role in the right-tail gains. For example,
the rise of digital culture and video games may be involved.
Play video games – it’s for the kids!