The racial gap in
average IQ is one of the
most important factors in modern American life. We
can tell how important it is because
we aren`t allowed to talk about it. The IQ gap is
rather like the
dog that didn`t bark in the Sherlock Holmes story,
palpable by its absence.
"If racial equality is America`s goal, reducing
the black-white test score gap would probably do more to
promote this goal than any other strategy that could
command broad political support." [
Next Achievement Test
, The American Prospect, Sept/Oct
When the 1960s-1970s burst of
spending failed to deliver quick results, however, the
topic was slowly driven out of
For example, last week the
New York Times ran what seems like its 100th article
recent years on the racial gap in school
Slow in Closing Gaps Between Races," by Sam
Occam`s Razor would suggest that the simplest and
thus most likely explanation for the persistent gap in
achievement is the equally persistent gap in aptitude.
But you aren`t supposed to mention that in the NYT.
Fortunately, a debate at the
American Enterprise Institute in Washington D.C. this
Tuesday morning, November 28, from 10 to 12 will address
this issue frankly:
The Black-White IQ Gap: Is It Closing? Will It Ever Go
Murray, along with his late
Richard J. Herrnstein, coined the term
"Flynn Effect" in recognition of the work done
by Flynn on the worldwide rise in raw IQ scores. Since
the 1940s, social scientists have known that the average
number of questions answered correctly on IQ tests has
been going up over time, requiring test-makers to make
scoring more rigorous. Flynn, in the 1980s, did the most
to bring this curious phenomenon to wide attention.
There have been
suggestions that it should have been called the “Lynn
Effect”, after British psychometrician
Flynn, a political scientist at
University of Otago in New Zealand, and
William Dickens of the Brookings Institute published
Americans reduce the racial IQ gap: Evidence from
standardized samples" in Psychological
Science. Looking at some major IQ tests such as the
Armed Forces Qualification Test, the Wechsler, and
the Stanford-Binet, they argue for a 4 to 7 point
decline in the gap between 1972 and 2002.
you`re wondering, this would be substantially bigger
than could be accounted for by increases in
interracial marriage, or in
mixed race people changing their designation from
white to black.)
changes over time in relative IQ scores is a challenging
problem. Variations in the precise methodologies of IQ
tests can affect the outcome substantially.
you don`t need to worry much about how, exactly, IQ
tests are constructed, since it`s not all that hard to
come up with one that`s at least roughly accurate. An
old saying among psychometricians is that
"Life is an IQ test." In other words,
practically all cognitive phenomena measurable are
positively correlated with the
general factor of intelligence. So it`s almost
impossible to devise a test that`s completely wrong.
On the other
hand, tracking subtle changes over the years raises
subtle technical questions.
analogous topic of the height of
NBA basketball players. No matter whether you
measure them with a doctor`s scale, yardstick, tape
measure, or just eyeball them, you will still come to
the quite correct conclusion that the average NBA player
Yet, if you
are trying to figure out whether they are still getting
taller over the years, methodology matters.
official NBA statistics, they are not. The
average height of an NBA player at the beginning of
the 2005-2006 season was 6`-7.18", down from 6`-7.36" 20
surprising, considering how much more globalized the
pool of athletes from which the NBA draws has become.
If you want
to be absolutely certain that pro basketball players
aren`t getting any taller, though, you`d need to
carefully investigate whether there were any changes
over time in how the NBA obtained these heights. Perhaps
the league used to allow players to
exaggerate their heights more, so they really are
getting taller? Or perhaps the soles of the sneakers
they wear when being measured have become thicker,
meaning they are actually getting shorter?
IQ tests change over the years in ways that are hard to
when the military`s Armed Forces Qualification Test was
standardized on a nationally representative sample of
15-23 year-olds in 1980, the white-black gap was an
oddly large 18.6 points (on a scale where non-Hispanic
white IQ is 100 and the standard deviation is 15).
Subsequent analysis showed that the unusually low
scores achieved by black males on the AFQT in 1980 were
caused by more blacks being likely to give up and not
finish the imposing105-page long paper-based test after
they realized they weren`t going to score well enough to
be allowed to enlist. (From 1992 through 2004, virtually
all enlistees in the
U.S. military had to score at least at the
30th percentile in IQ.)
In 1997, the
AFQT was re-standardized. But now it is given on a
computer that adjusts to how well the test-taker is
doing. If you miss a lot of early questions, the
program will then give you easier questions. This makes
taking the test less discouraging for low IQ
individuals, so that somebody who, say, would have given
up halfway through the old 105-page test and gotten a 65
might keep going and get a 75 instead.
On the new
computerized AFQT in 1997, the
white-black gap narrowed…to 14.7 points.
difficult question: how much of the relative black gain
on the AFQT of 3.9 points over 17 years was due to
changes in the test—and how much to actual improved
performance by blacks.
methodological alterations have, on the whole, been
biased in favor of higher minority scores. Test
publishers have been under
relentless pressure to eliminate any questions that
might appear biased against blacks.
the SAT scuttled its notorious "yacht
is to regatta" analogy question back in the
mid-70s. Then, to accommodate the
University of California`s attempt to evade
Proposition 209`s ban on affirmative action in
college admissions by finagling the entrance exam,
the SAT eliminated analogies entirely in this
This kind of
fiddling with the test could cause a modest rise in
wouldn`t be huge, however, because the tests were always
less biased than the media claimed. For example, blacks
did just as well, relatively speaking, on the
"regatta" question as on the overall Verbal SAT
test. And I wouldn`t be surprised if ridding the SAT of
analogies backfires and lowers the average black score
because African-American humor is quite oriented toward
analogy, simile, and metaphor: "Yo mama is so fat,
Flynn and Dickens came up with are quite curious. They
found strikingly different black IQs at different ages:
"95.4 at age 4, 90.5 at age 12, 87.0 at age 18"
"Our data give a current IQ for blacks age 24
of 83.4 or exactly 1.1 SDs below whites."
discrepancies could be explained by two contrary models
(or a combination of the two):
- Blacks could be getting smarter down through the
recent decades, and this massive increase just
hasn`t had time to filter through to black adults.
- Or blacks could be getting less smart compared to
whites as they age.
Then, the pseudonymous boys at
the Gene Expression blog
delved into this topic, looking at more IQ studies
than Flynn and Dickens did. At my suggestion, "Darth
graphed the average black IQ found by numerous
studies with year of birth on the horizontal axis:
line tracks average scores of black children, which are
now up around 89. The red line is for teens, now up to
87; the green line for young adults, now at 85, down a
few points from earlier; and the pink adult line has
long been flat at 85.
to show that young blacks born in the years leading up
to 1975 saw rising IQ scores. That`s not too surprising.
Those were prosperous years with black life improving in
many ways. I would guess that a shortage of calories for
pregnant black women stopped being a problem around
then. I wouldn`t be surprised if average height of
blacks grew quickly during those years too.
the results are more ambiguous.
Twin studies have shown that the heritability of IQ
tends to go up as you get older and create your
own environment—one more in touch with your particular
genetic predilections than the environment your parents
provided for you.
suggests an interpretation of this graph: that the
much-derided public schools, which are constantly
blamed for the poor performance of blacks, are actually
relatively good job of getting blacks to exercise
their brains, thus narrowing the white-black IQ gap
among the young.
problem comes when blacks leave the school system and
choose a lifestyle for themselves. They apparently fail
to impose enough intellectual rigor on themselves to
maintain the positive trend.
In any case,
rare public debates like the Flynn-Murray match-up on
Tuesday are oases in the intellectual desert. This
country very much needs more.