by Bob Seitz
The Rising Curve
Long-Term Gains in IQ and Related
Published by the American
Psychological Association, 1998
Rising Curve" summarizes some of the latest findings regarding the Flynn
Effect - the fact that IQ's in the developed nations have been rising at
a steady rate of about 3 points per decade for at least the last 70 years
(21 points), and probably at least for the last 100 years (30 points).
In "The Rising Curve", two questions are addressed:
is a long, long book report, but the Flynn Effect is of monumental importance,
and its cause(s), and the meanings of its effects are still cryptic.
is causing the Flynn Effect?
Are these improvements real improvements in intelligence, or do they reflect
specialized skills that facilitate better test scores without, necessarily,
providing a corresponding advantage in daily life?
What We Know About the
(1) Gains in IQ appear to have begun in the 1800's at or near the beginning
of the Industrial Revolution.
(2) The Flynn Effect appears be caused largely or wholly by environmental
the migration of people from rural to urban settings, with its associated
greater mixing of the gene pool, might lead to heterosis ("hybrid vigor"),
the general consensus is that the 30-point-or-greater observed gains in
IQ are far too large to be caused by purely genetic effects. Furthermore
, the Flynn Effect has apparently masked the 2.5-point-per-century genetically
based drop in IQs (because the less intelligent were out-breeding the more
intelligent) that has lowered the average IQ by, perhaps, 5 points over
the past two centuries.
have been greatest on tests of "fluid g" (educing patterns), and small
to non-existent on the Wechsler (and other) "crystallized g" subtests of
vocabulary, arithmetic, and general information. In other words,
the average citizen in 1900 knew nearly as many words, was at least as
good at arithmetic, and was virtually as well-informed as are people today,
but apparently, was far less able to discern patterns and recognize trends
than is the average citizen today.
Flynn Effect seems to operate across at least the upper half of the Pearson
Type IV or log-normal distribution function for human intelligence.Unfortunately,
I haven't seen any discussions concerning whether, when we get to higher
IQ levels, these Flynn-Effect IQ gains over time are gains in deviation
IQ's or gains in ratio IQ's. (Near the center of the distribution function
for human intelligence, deviation IQ's and ratio IQ's are nearly identical.
However, as IQ scores depart from the mean, the two types of scores diverge
Flynn Effect has already shown its full effect by the time children take
IQ tests. Whatever causes the Flynn Effect, it seem to have
raised children's IQs about 30 points above what they might have been in
The jury is still out regarding whether IQs tend to rise throughout adult
life as a result of the Flynn Effect.
Flynn Effect is happening at very nearly the same overall rate in the twenty
largest industrialized nations (3 points of IQ per decade), although the
breakdown of verbal versus non-verbal may be somewhat different from country
Neisser begins by citing three conclusions that he draws from the available
last conclusion is predicated upon work performed by calculations performed
by S. H. Preston and C. Campbell* that suggest that, under certain circumstances,
differential breeding won't alter the mean.
Scores on Intelligence tests
are rising, not falling.
The black-white gap in U'.
S. school achievement has closed dramatically in recent years.
There is no convincing trend
that the fact that families with lower IQ's are having more children than
families with higher IQ's is leading to a lower IQ for the population as
Chapter 1 - Dr. Neisser's
"Rising Test Scores" (Overview)
In the 1920's the Average U. S. Male Had a Mental Age of 14 (IQ of 87.5)
Dr. Neisser observes that in the 1920's, the country was dismayed to learn
that the average U. S. male had a mental age of 14 (IQ of ~87-88).
S. IQ Scores Rose from World War I to World War II
The average scores made by U. S. citizens on the Army General Classification
Test (AGCT) during World War II were higher than the corresponding scores
made on the Army Alpha Test during World War I.
Cause of the Flynn Effect Is Felt to be Environmental, But Why Is It So
There is general agreement that the causative agent(s) for this 3-point-per-decade
rise in IQ's is environmental, but no single cause that has been identified
explains the 3-point-per-decade constancy of this rate of rise in U. S.
IQ's, or the similar 3-point-per-decade IQ increases in other developed
Role of Inherited Genetic Factors Seems to Increase with Age.
Average Black Is As Smart As the Average White in 1950.
The difference in average IQ between African-American children and Caucasian
children was one standard deviation between African-Americans in the 1930's
and it remained at one standard deviation in the 1980's. However, because
of the Flynn Effect, the average IQ of the U. S.' African-American sub-population
is now equivalent to the average Caucasian IQ in 1950... an effect small
enough to be attributable to environmental differences?
SAT Reading Scores Earned by African-Americans Have Partially Closed the
Gap with Caucasian Reading Scores
As recently as 1978, the average gap between black and white reading scores
was 1.1 standard deviations; by 1990 it had declined to about 0.6 standard
Chapter 2 - Dr. James
R. Flynn's "IQ Gains Over Time: Toward Finding the Causes"
Gains in Fluid g (True Intelligence?),
Small-to-Negligible Gains in Vocabulary, Arithmetic, and General Knowledge
British subjects gained 5.4 points per decade over 50 years on the Raven
Progressive Matrices (RPM), which is considered to be the best test of
pure fluid g (noting that fluid g, in turn, is considered to be the proper
measure of true intelligence), but only 1.3 points per decade over 45 years
on vocabulary subtests. Gains on the Raven Progressive Matrices have averaged
about 7 points per year in The Netherlands, Belgium, Israel, and until
1968, Norway, and about 4 points per decade in Canada. It's worth noting
that, in spite of "teaching to the test" and Kaplan and Princeton Review
coaching programs, not only have scores on the U. S. Graduate Record Exam
(GRE) and Scholastic Aptitude Tests (SAT) failed to rise over the years,
SAT scores actually dropped in the years leading up to 1995. Of course,
the SAT and the GRE tend to measure crystallized intelligence rather than
fluid intelligence. The reduction in the number of hours devoted in U.
S. public schools to "core subjects" from 1,000 hours in 1940 to 300 hours
in 1995, together with the fact that many students who would not previously
have attempted college began to take the SAT, may help to explain this
divergence. (Recently, SAT scores have again begun to rise.)
Could Our 1900 Ancestors Have Been Able to Understand Baseball With Such
Dr. Flynn cites an example given by Arthur Jensen comparing a baseball
enthusiast with an IQ of 75 with a learned colleague with a high IQ and
no interest in baseball. The high-IQ colleague knew far more about baseball
than did the 75-IQ baseball enthusiast. The baseball enthusiast wasn't
able to tell how many players there were on a baseball team, or the names
of their positions. He didn't know the names of any of the Big League players.
Dr. Flynn argues that if the past century's gains in IQ scores represented
a true gain in intelligence, the average citizen in 1900, with an average
IQ of 70, wouldn't have been able to understand the U. S. national sport
of baseball. Dr. Flynn feels that Flynn Effect gains cannot be true gains
in intelligence. Otherwise, our forefathers wouldn't have been able to
run the world, or to produce the intellectual products that they did.
[Reviewer's Remarks: Note, though, that we are (a) talking about
one anecdote, and (b) about apples and oranges. First, we don't know the
IQ of the learned colleague. Second, we are talking about a sample of one.
Third, the Flynn Effect gains have been largely in non-verbal IQ. General
information, vocabulary, and the ability to perform arithmetic have changed
relatively little over the past 100 years. Is it possible that the baseball
enthusiast in 1900 might have had a verbal and general-information IQ of
87 or higher, and a non-verbal (pattern recognition) IQ of 63? Could such
an average individual have been capable of keeping up with the Yankees
and the Dodgers, particularly when his culture immersed him in it? (Please
be warned that your reviewer is an amateur speculating entirely outside
of his field of endeavor.)
Arthur Jensen argues: "But each person's crystallized intelligence would
closely parallel his or her fluid intelligence in the person's own culture."
However, the Flynn Effect has seen fluid intelligence rise considerably
faster than crystallized intelligence, and doesn't seem to support that
generalization... if, in fact, these rising IQ scores reflect rising intelligence
rather than some other phenomenon.
On the other hand, on the Flynn-Jensen side of this argument, if
I postulate that the average IQ was 70 in 1900, I have a problem explaining
writers with the erudition and command of language demonstrated by O. Henry
in his "Gentle Grafters" stories, or Emily Dickenson, Longfellow, Poe,
Wordsworth, Byron, and other great 19th century writers and poets. Also
there had to be readers who could appreciate them. And how does one explain
Thomas Jefferson and Benjamin Franklin, or the great 19th-century mathematicians,
scientists, and philosophers? Thomas Jefferson's ratio IQ has been estimated
at 170. If we subtract 30 points for the Flynn Effect, we're left with
a ratio IQ of 140. Converting this to a deviation IQ yields a present-day
deviation IQ of about 136. Could someone with a present-day IQ of 135 to
140 write the Declaration of Independence and the Constitution of the United
States? Another way to estimate the IQ's of Thomas Jefferson and Benjamin
Franklin might be to suppose that they had IQ's at the 1-in-100,000 level
among the colonists. That would correspond to a ratio IQ of about
190. Subtracting 30 points from it and converting it to a present-day deviation
IQ would give us about 150. However, since these historic figures were
verbally (as opposed to conceptually) closer to their present-day levels,
we might assign a verbal ratio IQ of 175 to Jefferson and Franklin, corresponding
to verbal deviation IQ's of about 160, with a present-day "conceptual"
IQ of about 140. Would that be high enough?
A more-correct way to calculate this might be to observe that in a population
whose mean IQ is 70, the 1-in-100,000 level should probably occur at a
ratio IQ of ~133.
Also, the average 4-or-4½-year-old today should be as ready for
school as the average 6-year-old was in 1900. Is that the case? It also
suggests another curiosity. At birth, mental age is virtually zero. However,
in principle, it should now be rising at nearly half again the rate at
which it climbed in 1900. So how do today's toddlers fare on tests that
ask them to, viz., "Touch your nose" compared to toddlers in Alfred Binet's
day? Are they able to perform these cognitive feats at earlier ages? If
the rise in g that the test scores indicate is real, people today should
be roughly twice as smart as the citizens of 1900. How would that play
out in terms of uttering first words, first sentence, vocabulary at a given
age, etc. (Vocabulary in infancy would seem to follow acquisition rules
different from total vocabulary in adulthood, since it would seem to be
constrained more by readiness for speech than by cultural demands.)
review of Chapter 8, below, quotes Dr. Richard Lynn's confirmation that
motor development and other indications of intelligence among 2, 4, and
6-year-olds are in fact far beyond those of children a century ago.
Test Scores Rise 47 Points Over 90 Years!
Next, Dr. Flynn discusses measurements by John Raven, Jr., of Raven Test
scores made by people with birth dates ranging from 1877 to 1967. Dr. Raven
found that British test-takers born in 1877 solved 23 of the 60 problems,
earning Raven-derived IQ's of about 74, compared with those born in 1967,
who solved 55 of the problems and exhibited Raven-derived IQ's
of 121. This represents a gain in fluid g over the 90 years of 47 points
of IQ, or roughly 50 points per century. Of course, those born in 1877
taking the test in 1942 at the age of 65 might have suffered age-related
decline in test scores. However, simple auxiliary tests suggest a scoring
decline for them of less than 10 points.
would have expected a Flynn-Effect overall IQ gain of 27 points over the
90 years between 1877 and 1967. If 47 points were the gain in Raven-Progressive-Matrix
scores, then we would have expected a gain of only 7 points in vocabulary,
arithmetic, and general knowledge. (assuming both components were equally
weighted on relevant IQ tests.) Actually, as we've seen, British scores
in those crystallized areas rose about 1.3 points per decade, corresponding
to an 11-12 point gain in verbal IQ's over the 90-year period. It isn't
too difficult to imagine someone in 1902 with an IQ of 88 by 1992 standards,
to have understood cricket, particularly when he was immured in it. Here
again, Dr. Flynn introduces his "understanding baseball" argument, and
here again, the hypothetical disparity between fluid g and crystallized
g, if such a notion is valid, suggests that Britishers born in 1877 might
have understood cricket well enough, while remaining quite poor (by 1992
standards) at Raven-type pattern recognition.]
Our Children Are So Smart, Why Don't Their Teachers Know It? If Our Grandparents
100 Years Ago Were So Stupid, How Did They Cope With the World?
Dr. Flynn next quotes studies of Wechsler and Stanford-Binet test scores
that show an overall IQ gain on these tests of about 25 points between
1918 and 1995. However, he observes that the Wechsler subtests show no
gains in arithmetic reasoning, small or nil gains for vocabulary, and negligible
gains for general information. Then he asks, "If one regards the present
generation as if it were a gifted class with a mean IQ of 125, where are
the reports from teachers of long experience that children today surprise
them with their speed of learning and sheer intelligence? If one treats
past generations as if they were a special needs class with a mean IQ of
75, one finds no evidence of widespread problems in coping with everyday
life. The frustration of our within-generation expectations concerning
enhanced cognitive skills, seems to imply that IQ gains have not been accompanied
by intelligence gains."
[(i.) These IQ gains would total about 10 points over a 30-year
teaching career, with a gain of about 4 points in verbal, arithmetic, and
general information capabilities. I'm not sure that teachers could detect
that. I can look back at my maternal grandparents, born in the 1870's,
and can't tell you how they would score on IQ tests. My grandmother had
to quit school after, perhaps, the fifth grade. I think my grandfather
graduated from the eighth grade. My grandmother took care of her house
all day. My grandfather arose at 4:30, made cottage cheese, and then performed
various odd-job services for his small-town dairy business. At night and
on weekends, my grandfather sat in front of his barn and hob-nobbed with
other townsmen or traded horses. Both of them read the newspaper, but neither
of them were immersed in intellectually stimulating environments, nor were
their friends and associates. There was much more farming and blue-collar
work in 1900 than there is today. I could imagine that they were well-adapted
to their world but, with skills of "book-larnin'" abstraction that had
been allowed to atrophy through lack of stimulation, they might have done
poorly as fortyish adults on IQ tests, especially if they were to have
taken them "cold". If Scrabble champions can learn in excess of 250,000
words, surely my grandparents could have learned the 20,000 to 30,000 words
they would have needed to be fully literate in their day and ours. Arithmetic
had to be performed with pencil and paper before adding machines prevailed.
(ii.) If the amount of time invested in the "core curriculum" has dropped
from 1,000 hours in 1940 to 300 hours today, could it be that children's
rising IQ's have been taxed to learn approximately what they learned 60
years ago with allegedly less than 1/3 rd of the classroom instruction
time that they received 60 years ago? (Of course, they may be learning
much-more-useful information today than they did then.) Also, extracurricular
activities today are an order of magnitude more extensive and intensive
than they were in 1940.
(iii.) Our present rate of technical progress is remarkable, drawing upon
people whose IQ's would seem to have been too low for such intellectual
contributions in 1940.
(iv.) There is the suggestion of many more extraordinary prodigies these
days than reached my ears in the 1940's. One never heard about children
who started to read at the age of one, except for William Sidis, and, in
1945, Merrill Kenneth Wolfe. Reading at 3 was considered extraordinary
in those days. This is an important question. If this is true, it would
argue in favor of biological or very early environmental factors as opposed
to cultural influences. Of course, it's also possible that cases in which
children started to read in the neighborhood of 12 months didn't make it
into the media. It seems to me that it would be helpful to know whether
prodigies existed in the 20's and 30's who spoke their first sentence at
or around 6 months, and who began to read at or around 12 months.
One indication that reading at 12 months was considered beyond the pale
might be found in Eric Temple Bell's description of Karl Friedrich Gauss,
"The Prince of Mathematicians" in his "Men of Mathematics". Bell wrote,
"In all the history of mathematics, there is nothing even approaching the
precocity of Gauss as a child. Though it seems incredible, Gauss showed
his caliber" [found an error in his father's arithmetic] "before he was
three years old."
"Before this, the boy had teased the pronunciations of the letters of the
alphabet out of his parents and their friends and had taught himself to
read. Nobody had shown him anything about arithmetic."
The fact that Dr. Bell considered Gauss' story incredible would seem to
imply that he had never heard of a similar story. (Of course, there would
have been William Sidis, reading the New York Times at 18 months, but Sidis
is the stuff of legends even today.)
(v.) At the same time, no one should suppose that verbal, arithmetic, and
general information skills among the brightest 19th-century literati were
significantly inferior to present-day intelligentsia. The writings of the
better-known poets and authors of the 18th and 19th centuries, such as
O. Henry, Emily Dickinson, Wordsworth, Lowell, and other wordsmiths, leave
little doubt regarding their vocabularies, their abilities to use them,
and their far-ranging funds of knowledge. In like manner, their logophilic
audiences had to possess the verbal capacities to understand and appreciate
One factor that might enter into these deliberations is that of the cognitive
and knowledge-based demands imposed by one's culture. Nineteenth century
culture would have placed demands upon one's knowledge of arithmetic that
may have been lessened by the appearance of calculators, automatic cash
registers, and computers. Vocabulary requirements probably haven't changed
much since I was a child, and they might have declined slightly since then.
(One yardstick might be to compare the 1930's Readers Digests' "How to
Increase Your Word Power" with the same vocabulary lists today.)
Could it be that fluid g, and its potential
for higher levels of crystallized intelligence, has risen as dramatically
as it seems to have risen, but that our current cultural milieus don't
Dr. Flynn continues,
"Problems remain even for those who abandon g but who accept the idea the
distinction between the Raven as a measure of fluid intelligence and the
Wechsler-Binet tests as adding a dimension of crystallized intelligence.
Theory posits a functional relationship between these two, so that a problem
that afflicts one transfers to the other. Take the problem of putting past
generations at a mean IQ of 70 or 80 on tests of fluid intelligence. Such
populations should not be capable of soaring much above that in crystallized
intelligence, the skills they need to deal with the real world." "It is
quite another thing to imagine people acquiring normal levels of knowledge
and vocabulary if their fluid intelligence never, during their entire
lives, rose much above the level of mental retardation."
seems to me to be wrong with this syllogism, since Dr. Raven's study shows
that, as a matter of record, my grandparents' generation had arithmetic
skills, general knowledge, and vocabulary levels not terribly far below
our own, and at the same time, fared badly (by today's standards) on the
Raven-Progressive-Matrix test of fluid g. If their overall IQ scores stood
at 70, then their verbal IQ's must have been ~90 and their fluid-g IQ's
~50... unless, of course, somehow, these Flynn-Effect IQ gains aren't really
Could Be Causing the Flynn Effect?
Next, Dr. Flynn examines possible causes for these IQ gains.
(i.) Nutrition: An obvious candidate is better nutrition. However,
height gains are attributed to better nutrition, and these gains tapered
off in the 1970's and have been minuscule since the 1980's. Further, studies
of the impact of nutrition upon IQ have shown little correlation once children
are nourished above the serious malnutrition level. For example, famine
among the Dutch during World War II had no effect upon IQ. Likewise, the
Great Depression failed to halt the upward march. Anyway, this wouldn't
explain the continuing 3-point-per-decade rise in IQ's. Beyond that, in
1900, a large fraction of the population lived on farms. It's not clear
that they were malnourished (although important minerals, such as iodine
and important vitamins were sometimes missing from their diets, particularly
during the winter, when fresh fruits and vegetables were unavailable).
(ii.) Test Sophistication
Increasing test sophistication seems like another likely candidate, but
first, the gains are too great, and second, such gains should have run
their course decades ago. Studies aimed at this question have failed to
uphold test sophistication as a significant factor. The argument upholding
increased test sophistication as the cause of the Flynn Effect was, to
quote Dr. Flynn,
"The last generation was scrupulous and painstaking, the present generation
tends toward personal liberalism. The former wasted time trying to get
every item correct; the latter are prone to intelligent guessing and finish
more items within the allotted time."
"The hypothesis............has now been proved false. John Raven analyzed
his own test and reported that responsible test takers persist to the end.
In addition, people do not get items right or wrong by guessing but by
mastering or not mastering rules that govern the orderliness of the matrix
(Raven, Raven, & Court, 1995, p. G59)."
Dr. Flynn says,
"The first subhypothesis, concerning better teaching of school-learned
content, has already been falsified by the pattern of IQ gains over time.
As I have shown, gains drop as one goes from Raven's type tests to performance
tests to verbal tests to Wechsler subtests like Arithmetic, Information,
and Vocabulary. This implies that the gains tend to disappear when material
closer to the learned content of the school curriculum is tested.
"This leaves the second subhypothesis, namely, that schools are teaching
better decontextualized problem-solving skills. Perhaps they are, but the
hypothesis is empty unless (a) these school-taught skills are identified;
(b) they are linked to the problem-solving skills used on IQ tests, particularly
culture-reduced tests of fluid g; and (c) they are linked to some kind
of real-world problem solving or, the greatest puzzle, it is explained
why there is no such link. The very fact that children are better and better
at IQ test problems logically entails that they have learned at least that
kind of problem-solving skill better, and it must have been learned somewhere.
However, simply to assert that the enhanced IQ test skill can be equated
with some enhanced school skill is arbitrary and vacuous."
Socio-Economic Status and Urbanization
"Using algebra, one can show that even if urbanization totally eliminated
[farmers and rural workers], only 3.2 points of the 24-point gain would
be explained. Calculation of the IQ gain of children whose parents had
urban occupations gave a similar result: Only 3 points of the total sample's
estimate of the effect of the total package is possible, but an estimate
of 6 points is plausible and tallies with the Dutch data. There, 5 points
out of 20 were explained by a package of Socio-Economic Status plus test
sophistication plus education."
(v.) Looking for National Differences
industrialized nations show roughly comparable rates of gain in average
Raven-Derived IQ's. However, Israel showed a small gain from 1969 through
1974, and then a rapid gain (of 8 points over a 10-year period) after that.
From 1968 through 1980, the gain in Norway declined from about 7.2 points
per decade to about 2.4 points. These anomalies might offer clues to the
causative factors that are behind the Flynn Effect.
pooled all the countries' data to arrive at a curve that is essentially
a straight line with a slope of 6 points per decade. He concludes,
"The pattern is unsettling. It is as if some unseen hand propelled scores
upward at an unvarying rate between 1952 and 1982, a rate of 6 points per
decade, with individual nations scattering randomly around that value."
Interestingly, Belgium has the highest-listed average Raven-derived IQ
level, at 112.
(i.) Similar gains are found in all the nations for which data exist.
(ii.) Culture-reduced tests show gains averaging about 6 points per decade.
Performance tests show about 3-to-6-point-per-decade improvements. Verbal
tests show increases of 3-points-per-decade or below. Tests close to the
content of school-taught subjects such as arithmetic reasoning, general
information, and vocabulary show little or no gains.
(iii.) The fact that these gains are fully present in young children means
that these causal factors are already acting in childhood. It's unknown
whether or not they tend to raise IQ's throughout life.
(iv.) The first set of causal factors involved test-taking sophistication,
but these are evidentially weak. The second set of factors include nutrition,
socio-economic status, urbanization, eradication of childhood diseases,
effects of the Depression and WW II, upgrading of preschool environment,
TV, and education. Since 1950, these factors only seem to account for 17%
to 20% of the observed rise.
"I am convinced that neither giftedness (the capacity to learn more quickly
and make creative leaps) nor understanding-baseball intelligence (the capacity
to absorb the usual rules of social behavior) has increased significantly.
But even I believe that enhanced problem solving in the test room must
signal some kindred gains in problem solving in the real world, however
subtle. Identifying these two effects and comparing them could provide
a priceless guide from effect to cause."
Chapter 3 - Dr. Carmi
Schooler's "Environmental Complexity and the Flynn Effect"
Dr. Schooler argues that the Flynn Effect gains are real. She questions
(as I have questioned above) whether the projected IQ of 75 in 1900, though
with IQ-90-to-100 vocabulary, arithmetic skills, and general knowledge,
would be comparable to an IQ of 75 today. However, she doesn't discuss
whether someone in 1900 with an overall IQ of 75 (by today's standards)
and a "pattern-recognition" IQ of 50 would have been able to run the world
Chapter 4 - Patricia
M. Greenfield's "The Cultural Evolution of IQ"
Dr. Greenfield argues that the pattern of the Flynn Effect enhancements,
favoring non-verbal improvements over verbal improvements, must be culturally
driven. She cites an 11-point average rise in IQ scores among East Tennessee
mountain children between 1930 and 1940 as their school environments improved.
She then invokes increased visual imagery beginning with movies and continuing
on to video games. She argues that
"The analysis presented in this chapter leads to the conclusion that nonverbal
IQ tests are, in fact, more, not less, culture sensitive than verbal tests.
Indeed, this fact has been known since the 1950s, mainly because of research
in Africa (see Wober, 1975, for an excellent summary of research on ability
testing in Africa). Why is this the case? ....nonverbal or performance
tests do rely on their own language of visual conventions. As I have shown,
even the name culture reduced is a misnomer for visual tests such
as the Raven Progressive Matrices."
She concludes with a section entitled, "If IQ Is Going Up, Are People Becoming
More Intelligent?" She says,
"My answer is yes but in very specific ways. These ways include
everyday examples such as provided by the legion of computer-literate hackers."
Chapter 5 - Wendy M.
Williams' "Are We Raising Smarter Children Today? School- and Home-Related
Influences on IQ"
In the 1930's, mean educational attainment in the United States was 8-9
years, which meant that non-high-school graduates were taking IQ tests.
In the 1990's, mean educational attainment is 14 years."
Dr. Williams agrees with Dr. Greenfield that culture-reduced tests may
actually be culture-enhanced. She identifies many possible causes arising
during the latter half of the 20th century but doesn't address the fact
that the Flynn Effect began no later than the early 20th century, and that
the rises have been approximately constant over time. However, she presents
some interesting facts.
Reading Becoming a Lost Art?
With the prevalence of TV and video games, reading, like arithmetic, is
becoming a lost art. She suggests comparing Raven test scores of children
who have access to TV and/or video games with those who do not.
Classroom Teaching Stresses Insight and Understanding vs. Yesterday's Rote
She also observes that there has been a major shift in the classroom away
from declarative knowledge (knowing facts) to procedural knowledge (knowing
how to) and strategies. Also, taxonomic, categorical reasoning is emphasized.
Thus, a question such as, "What is the boiling point of water?" might better
have been answered by the 1930's student, whereas a "complete-the-series"
question such as 3 5 7 9 11 13
__ , might better be answered by a 1990's child.
Academic Learning Time Has Dropped from 1,000 Hours in the 1930's to 300
This must almost certainly place downward pressure on the learning of facts,
information, and vocabulary. Happily, offsetting factors are maintaining
such learning at approximately the 1930's levels, while accompanying this
with gains in "pattern-recognition intelligence" or, perhaps, fluid g.
to the Test" Has Become Prevalent.
This active teaching of test-taking strategies could be resulting in some
improvements in test scores.
The Home Environment Has Changed
Among the changes in home environment, she lists,
Chapter 6 - Marian Sigman's
and Shannon E. Whaley's "The Role of Nutrition in the Development of Intelligence"
Trend Toward Smaller Families
Greater Educational Attainment
Trend Toward Urbanization
Changes in Parental Style
Changes in Stress Levels Affecting
Pregnant Women and Their Babies
Improvements in Health and Nutrition
These two women are arguing that improved nutrition must have played some
role in rising intelligence, but,
"At the same time, we are convinced that the rise in intelligence is not
due entirely to nutrition."
They argue that it may not be valid to compare increases in height with
increases in intelligence. They warn that,
"A diminution in the federal food programs has the potential to cause a
fall in intelligence analogous to the rise that has been documented up
to this time".
Chapter 7 - Reynaldo
Martorelli's "Nutrition and the Worldwide Rise in IQ Scores"
Dr. Martorelli concludes,
"...it is reasonable to suggest that the remarkable nutritional improvements
that occurred in many countries during the second half of the 19th and
the first half of the 20th centuries probably resulted in improved intellectual
performance. However, intelligence test scores continued to increase in
northern Europe and the United States at an undiminished rate into the
late 1980s, after the disappearance of nutritional deficiencies and poor
physical growth during early childhood."
"One key reason for rejecting nutrition as an explanation of recent trends
in intelligence test scores is that cohorts of young adults in Scandinavian
countries, The Netherlands, and the United States measured since 1970 are
unlikely to be undernourished during critical childhood phases of development,
yet available evidence does not indicate the plateau in IQ scores that
would be expected."
"A second reason is that there is no conclusive evidence that greater intakes
of vitamins and minerals affect cognitive performance among schoolchildren
in developed countries."
Chapter 8 - Richard
Lynn's "Support of the Nutrition Theory"
IQs Have Increased Along with Heights.
Head Sizes and Brain Sizes Have Also Increased.
When One Homozygotic Twin Has a Larger Brain Size Than the Other (as a
Result of Better Prenatal Nutrition), It Has a Higher IQ.
The Fact That Nonverbal Rather Than Verbal intelligence Has Risen Is Consistent
with Dr. Lynn's Nutritional Model
"Fourth, the type of abilities that have shown the greater secular increases
in intelligence are precisely those that are most affected by nutrition,
namely the nonverbal reasoning abilities, sometimes called fluid intelligence,
rather than the verbal-educational abilities, sometimes called crystallized
In the twin studies cited in (3), the twin with the larger brain had a
higher fluid intelligence. Also, nutritional supplements tend to raise
Full Flynn Effect Is Showing Up In 1-to-2-Year-Olds, Which Could Be Mediated
Only By Nutrition.
Dr. Lynn observes that "the full magnitude of the
Flynn Effect, as assessed by the Wechsler tests, has occurred among 4-
to 6-year-old children as well as among schoolchildren and adults (Flynn,
1984), and it has also been present among 1- to 2-year-olds assessed by
infant intelligence and motor development tests (Hanson, Smith, & Hume,
1985)." This leads Dr. Lynn to conclude that only
nutrition could produce the full Flynn Effect this early in life.
Dr. Lynn argues that the improvements shown with the Raven Progressive
Matrices are spurious, transfer-of-training results, but that,
"The IQ gains on the Wechsler tests, amounting to approximately 3 IQ points
per decade, should be regarded as genuine increases of intelligence,..."
Dr. Lynn credits the 2.7 IQ points per decade rise in British 5- to 11-year-olds
on the Coloured Progressive Matrices over the 33-year-period 1949-1982
(Lynn & Hampson, 1986) as more significant because all the children
were learning math in school throughout the period, so that the school-learning
factor is controlled. He also notes that this 2.7-point-per-decade IQ increase
is close to the 3-point-per-decade increment found in a number of countries
on the Wechsler.
Chapter 9 - Robert
M. Hauser's "Trends in Black-White Test-Score Differentials: I. Uses and
Misuses of NAEP/SAT Data"
Dr. Hauser observes that the NAEP (National Assessment of Educational Progress)
tests are mandatory whereas the SAT test is self-selected by students who
plan to go on to college.
references Ceci's study that schooling raises IQ score by about 2 to 2.5
points of IQ per year of study.
Dr. Hauser observes that between 1970 and the late 1980's, black-white
reading test-score differences decreased by 50%, the mathematics differentials
decreased by 25% to 40%, and the gaps in science by 15% to 25%. However,
he also points out that there is cause for concern in the 1990-1992 data,
where these gains appeared to be eroding.
Chapter 10 - David
W. Grissmer's, Stephanie Williamson's, Shiela Nataraj Kirby's, and Mark
Berends' "Exploring the Rapid Rise in Black Achievement Scores in the United
This paper. like the preceding paper, is primarily about African-American
test scores rather than the Flynn Effect.
Chapter 11 - Stephen
J. Ceci's, Tina B. Rosenblum's, and Matthew Kumpf's "The Shrinking Gap
Between High- and Low-Scoring Groups: Current Trends and Possible Causes"
authors use the shrinking gaps between blacks and whites to argue that
black IQ's, that have stubbornly remained about 1 standard deviation below
white IQ's since 1918, are finally rising... i. e., that the black-white
IQ gap may finally be closing. However, they're also worried about the
fact that black test scores seem to be dropping again.
They observe that a "dumbing down" of American (but not British)
textbooks occurred beginning after World War II (Hayes, Wolfer, and Wolfe,
1996). They also found that the same cohorts who were exposed to these
"dumbed down" textbooks in school experienced later declines in their verbal
(but not math) SAT scores in direct proportion to their years of exposure.
This dumbing down of books affected the SAT patterns of even the highest
scoring group, those with a verbal score of over 700; their numbers were
diminished despite the greatly expanded pool of test-takers.
Chapter 12 - Kim Hsiung
Huang's and Robert M. Hauser's "Trends in Black-White Test-Score Differentials:
The WORDSUM Vocabulary Test"
This study focussed upon black-white vocabularies, upon vocabularies measured
over time, and upon vocabulary scores tallied by year of birth. The WORDSUM
vocabulary surveys were based upon carefully chosen 10-word lists of vocabulary
selected by R. L. Thorndike. Women and men did equally well on the tests.
White men and women born in the 1909-1919 time frame averaged 6.5 correct
answers; blacks born during that period averaged 4 successes. As
birth dates rose, the whites gradually dropped to 6 correct answers, while
the black word count rose to 5.5. When socioeconomic background and years
of schooling were controlled, subjects in the age ranges from 30-39 and
from 40-49 scored about 0.3 words (5%) higher than subjects 20-29, while
subjects 50-59 and 60-65 showed no advantage over test-takers who were
20-29. When social background is controlled there has been a downward trend
for both blacks and whites. Average levels of paternal and maternal schooling
has grown by 5 years among whites, and by 7 years among blacks. "Our examination
of word frequency ranks suggested that the difficulty of WORDSUM items
may have increased over the decades." In other words, the drops in vocabulary
scores for both blacks and whites may have been a result of the words on
the tests becoming less familiar.
Chapter 13 - Richard
Lynn's "The Decline of Genotypic Intelligence"
Dr. Lynn concludes that differential birthrates between the smarter and
duller layers of the population have resulted in a genetic decline of about
5 points of IQ over the last 200 years.
Chapter 14 - Irwin
D. Waldman's "Problems in Inferring Dysgenic Trends for Intelligence"
writer devises some reasons why Dr. Lynn's conclusions might be incorrect.
Chapter 15 - Samuel
H. Preston's "Differential Fertility by IQ and the IQ Distribution of a
The author concludes, on the basis of genetic calculations, that if relatively-bright
children born to low-IQ parents can move up to mate with high-IQ partners,
then dysgenic trends need not prevail. Dr. Preston concludes,
"There is no reason to believe that higher fertility among persons of lower
IQ will lead to a deterioration in the IQ distribution over time. This
intuition appears to be based upon an assumption that IQ groups are isolated
from one another and that children always inherit the IQ of their parents.
However, there is substantial mobility from parent to child in IQ scores,
and this mobility is sufficient to offset the effect of fertility differentials
on IQ trends. What matters for IQ distribution is how the current pattern
of fertility differentials relates to those of the past---those that have
given rise to the current distribution. It is necessary to understand IQ
transmission as a macro-level population process to appreciate how fertility
differentials affect the IQ distribution."
Dr. Preston isn't saying that this dysgenic threat can't happen---only
that it doesn't have to happen, and, given realistic assumptions about
the world, it's more likely that it isn't happening than that it is.
Chapter 16 - John C.
Loehlin's "Whither Dysgenics? Comments on Lynn and Preston"
Dr. Loehlin first observes that in the United States, this dysgenic trend
that caused an average IQ decline of 5 points over the past two centuries
has slowed almost to a halt, because smaller family sizes are now found
with lower-IQ as well as higher-IQ families. In second-world countries
like Mexico, this dysgenic trend is probably at its peak, while in third-world
countries like Kenya it hasn't yet started, since both high-IQ and low-IQ
parents are having large families. Dr. Loehlin agrees with Dr. Lynn that
this dysgenic trend has produced an IQ decline of about 5 points in 200
He then analyzes Dr. Preston's results, but concludes that in the first
world, over the last 200 years, this dysgenic trend has been real, and
has presumably lowered IQs by a few points. He also underscores the fact
that the Flynn Effect must--and does--greatly override this dysgenic trend.
"Thus, there remains a paradox here: a rising tide raising leaking boats,
if you will. I do not think that the analogy holds in all respects: that
there is some point at which the boats sink to the bottom, and the rising
tide becomes irrelevant. Nevertheless, I do not believe that it is sensible
to ignore the possibility altogether, and I think that it is a notion like
this one that underlies Lynn's concerns."
Dr. Loehlin mentions the
possibility of intrafamily eugenics, in which the husband and wife select,
from among the sperm and ova they produce, those they deem genetically
most desirable for their offspring. Instead of taking genetic pot-luck,
they would select from their available genetic options. The technology
for accomplishing this isn't quite here yet, but might become available
within the next decade or two. He also mentions the possibility of encouraging
a positive eugenic trend by providing child-care facilities for graduate
Summing It All Up
Whatever else is true, the Flynn Effect is certainly a striking phenomenon.
Two problems that arise in discussing it are:
These Gains Should Be Exponential, Not Linear!
If something is increasing at a rate of 3% a decade, it's increasing exponentially.
In a century, the associated overall gain should be 35% as opposed to 30%
if the gains were simply additive. If it's increasing by 2.7% a decade,
the 100-year multiplier would be 31%. Dr. Flynn's composite curve for the
rate of rise of Raven's test scores from 1952 to 1982 in Chapter 1, Section
E, subsection v, shouldn't be a straight line. It should be an accelerating
curve, with a slope of, e. g., 5.5 points per decade for the first decade,
6 points per decade for the second decade, and 6.5 points per decade for
the third decade, since that's how exponentials work.
Is the Flynn Effect Boosting Ratio IQs Or Deviation IQs?
As long as we're dealing with IQs that are close to the mean, there isn't
much difference between ratio IQs and deviation IQs. A 30-point change
in the ratio IQ corresponds to a 28-point change in the deviation IQ. However,
a 50-point decrement in the average deviation IQ translates into a 60-point
drop in the ratio IQ. John Raven found that British citizens born in 1873
had an average Raven-IQ score that is 47 points less than that of the British
born in 1967 (see Chapter 2-C, above). Extrapolating that to today, we
might postulate, for the Britisher born in 1873, an IQ ~50 points
below that of his great-great-grandson, born in 1973, insofar as inductive
reasoning and pattern recognition (and perhaps, ease of learning) is concerned.
But if that 50 points represents 50 points of deviation IQ, then we're
looking at 60 points of ratio IQ! While an elegant and knowledgeable talker,
that average Britisher would have had the pattern-recognition and intellectual
capacities of today's 6-year-old!
I suspect that the changes documented as the Flynn Effect are operating
on something more like mental age and ratio IQs than the less-meaningful
deviation IQ. Ratio IQs are based upon mental ages, and mental ages are
additive. I have found both concepts useful, and it may be so in this case.
But even if the Flynn Effect affects mental ages rather than deviation
IQs, the average Britishman born in 1873 would have sounded competent,
but would have had the pattern-recognition and intellectual capacities
of today's 8-year-old... more plausible, but still not very plausible.
It Might Be Convenient to Define Three Interpretations of What's Happening.
Flynn Effect is 0% Real, 100% Artifact
is more or less Dr. Flynn's position. Dr. Flynn feels that there must be
some real-world benefits attributable to the enhanced problem-solving skills
that underwrite these rising IQ scores, but he doesn't believe that underlying
intelligence has increased significantly. One of the ideas is that tests
like the Raven are actually highly culture-dependent. Of course, lesser
gains have been registered on other tests such as the Wechsler and the
Stanford Binet, but these could also have profited from our ever-more-stimulating
environment. People in 1900 were just as bright as we are today, although
they wouldn't have scored as well on our IQ tests.
One of the problems with this scenario is that we don't know how to train
people to permanently raise their scores on arbitrary IQ tests by 30 points.
The Abecdarian and Milwaukee Projects (and others) represented all-out
attempts to boost children's IQs, beginning shortly after birth. Long term,
it's doubtful that the permanent gains exceeded 5 points of IQ in adulthood.
On the other hand, if IQ tests mean anything at all, the Flynn Effect has
boosted people's IQs by 30 points by more. If so, this would suggest a
startlingly-large environmental influence upon IQ.
Flynn Effect is 50% Real, 50% Artifact
Effect partially represents an increase in our underlying intelligence,
effectively raising it by than 33% over the past century. Today, the average
citizen in the industrialized nations has a 1900-equivalent mental age
of about 21.33 years, a ratio IQ of 133 on their scale, and a deviation
IQ of 130 on their scale.
sounds more plausible, since it's a compromise. Now we're trying to train
someone with a ratio IQ of 75 to reach a verbal, arithmetic, and informational
level of IQ 88-90. Their brightest individuals, with ratio IQs above 200,
would only have fallen above our (deviation) IQ-143 level.
The Flynn Effect is 100% Real
The Flynn Effect represents an increase in our underlying intelligence
(fluid g), effectively doubling it over the past 100 years. Today (according
to this scenario), the average citizen in the industrialized nations has
a 1900-equivalent mental age of 32 and a ratio IQ of 200 compared to the
average citizen in 1900. This intellectual gain hasn't been fully realized
in the culturally-mediated areas of vocabulary, arithmetic, and general
information because we've developed inferential capabilities rather than
rote-mechanical knowledge. Also, reading and arithmetic have sagged a bit
because of TV. However, we've managed to learn in 300 hours a year about
as much as we learned in 1,000 hours a year of drill in 1900.
There are a couple of sticking points with this scenario. We're postulating
the idea that the society of the late 1800's was able to train individuals
with ratio IQs of 50, or deviation IQs of the order of 60, to nearly the
level of today's average citizen in the areas of arithmetic, vocabulary,
and general information. But we're unable to do that with our "mentally
challenged" with IQs of 60. Also, the 19th century's brightest individuals,
with ratio IQs above 200, would have been only a little brighter than our
average indviduals today. And a mental giant like William Sidis would have
been a seemingly-impossible intruder in such an era. (However, it might
be worth noting that William Sidis was considered to be sui generis.
In 1900, it was newsworthy when a child began reading before the age of
are dilemmas with all three of these scenarios. As mentioned above, efforts
to train people to score higher on IQ tests have never produced gains of
more than a few points. Yet we're seeing 30% gains over a 100-year period--or
42% gains from the perspective of someone back in 1900. Are these gains
environmentally-inspired... something that most psychometrists might well
have considered impossible? Is environment far more important in
the nurturing of intelligence than we've been led to suppose (assuming
that the Flynn Effect is truly boosting intelligence)?
assume that the Flynn Effect isn't truly emblematic of rising intelligence,
then we have to explain how people are able to consistently score better
on IQ tests when we haven't been able to find any way to train them to
do this. How can they score better in the testing room without being able
to "score" better in the world outside the testing room?
assume that the Flynn Effect is truly indicative of rising intelligence,
then we have to explain how the citizens of the nineteenth century and
before, were able to perform as well as they did with present-day core
IQs of no more than 50 or 75.
a middle-ground assumption that the world of 1900 had an average IQ of
75 doesn't make it easy to fathom how they could have done what we know
they did. Based upon this scenario, their brightest individuals--Maxwell,
Dirac, Einstein, Heisenberg, Sir James Jeans, Sir Arthur Eddington--couldn't
have had deviation IQs above a present-day level of, perhaps, 160.
It's exciting to think that IQ scores have risen as much as they have.
If the Flynn Effect really represents even a partial increase in average
intelligence, it would seem to me to bode bode well for the future of humanity.
IQ gains of this caliber are stunning in the light of all the painstaking
research that has been performed showing how little effect environmental
factors have seemed to produce on IQ scores.
What do you think about this?
enough, there is current evidence that in the United States, the Flynn
Effect has been running 3.5% to 4% since 1980.