the difference between the groups as a whole. But
there are other statistical differences between different
population groups that are widely known in a different
context – across the generations.Smarter than your mum
Intelligence researchers throughout the world have had
a collective headache for 35 years – and there have been
no indications of it beginning to fade. The headache was
triggered in 1984, when scientists were introduced to a
mysterious phenomenon by James Flynn, who was then
a professor of political studies at the University of Otago
in New Zealand. Flynn had become aware that the
companies that design intelligence tests were needing
to revise them regularly. Either they had to make the
questions slightly more difficult, or they had to adjust
the score system. The companies were doing it to main-
tain the bell curve rule – that the test scores of a large
group of people must always result in a normal distribu-
tion with an average of 100. If people got better at the
tests, the testing companies have to mark them down,
or make the tests harder.
Flynn discovered that the
general trend in the companies’
adjustments was to make the
questions harder. So as tests
became ever more difficult over
time, better mental capacities
were required to get the same IQ
score as someone tested earlier.
While it was widely known
that the tests were being
adjusted, Flynn was the first to
calculate the consequences, and
he found out that the effect was
much larger than anyone had
suspected. The numbers them-
selves weren’t huge. Through
the 20th century, tests were
adjusted so it became averagely
0.3 IQ points harder to get the
same score from one year to the
next. Such an annual rise
doesn’t seem much, but it means a lot when scientists
compare the IQ of different generations.
James Flynn has scrutinised results of the IQ tests
that many nations use when they accept recruits into
the military. The consequence is very clear once the
results are cleansed of the adjustments made to the
tests over the years. If the average of soldiers tested in
1992 is the usual 100, those tested 50 years earlier in
1942 would have had an average IQ of only 73.
The Flynn effect demonstrates that the population as
a whole became ‘smarter’ over the generations, all the way
up through the 1900s. The development is the same in all
the 35+ nations he has studied. In spite of much specula-
tion, intelligence researchers have not found any clear
explanation of the effect. Flynn himself believes that it is
to be found in the external environment – the time and the
society in which we grow up. In particular, developments
in education have meant that ever more people have
learned to think in the way that is rewarded in IQ tests.As Flynn once said “We educate people to take the
hypothetical seriously, to use abstractions, and to link
them logically.”
Better nutrition, global rises in GDP, and the minimi-
sation of infectious diseases which can affect develop-
ment are other possible contributing factors to what is
known as the Flynn effect.
Yet there is every indication that the Flynn effect is
decreasing, and even reversing. The most recent military
IQ tests of some nations, such as the Nordic countries,
show that the effect has become invisible since 2000.
Our most recent new soldiers are no more intelligent
than the soldiers of the late 1990s.
The Flynn effect and the lack of a certain explanation
for it reveal weaknesses in the way in which scientists
measure intelligence. Following Flynn’s discovery, it’s
clear that an IQ score does not paint an accurate picture
of a person’s intelligence without including information
on the time when the test was made.
Others have criticised IQ tests and the whole idea of
the g factor for painting too narrow a picture of our
mental capacities. According to these critics, intelli-
gence should be defined in a totally different and much
broader way.Many intelligences
Maybe we do not have just one, but rather a long series
of different intelligences which function completely
independently of each other. That is the essence of the
theory of intelligence introduced by American psycholo-
gist Howard Gardner in 1983. He disagreed with the idea
of a central g factor that makes up the basis of all our
intellectual capacities. Instead Gardner listed a total of
seven intelligences, and has since expanded his theory
to include another two. Apart from the classic subjects
included in traditional IQ tests, Gardner’s theory also
includes capabilities such as musicality, physical abili-
ties, and social intelligence. The mission of his contro-
versial new theory was clear:
“While we may continue to use the words ‘smart’
and ‘stupid’, and while IQ tests may persist for certain
purposes, the monopoly of those who believe in a single
general intelligence has come to an end. Brain scientists
and geneticists are documenting the incredible differen-
tiation of human capacities, computer programmers are
creating systems that are intelligent in different ways,
and educators are freshly acknowledging that their
students have distinctive strengths and weaknesses,” he
wrote in 1999.
Gardner’s theory about intelligences has received
much attention, and it was particularly well-received by
teachers. The theory focuses on the fact that children
learn in different ways, and so individual approaches,
also known as learning styles, are needed in order for
individuals to benefit the most from their education.
Intelligence researchers are not very enthusiastic.
Some criticise Gardner’s theory for being too broad and
for working with factors that are impossible to measure.
Others consider it a problem that the many capabilities,
talents and interests included in the theory undermine
the very concept of intelligence. So most intelligence
researchers still stick to the classical understanding ofThe monopoly
of those who
believe in a single
general intelligence
has ended.INTELLIGENCE RESEARCHER HOWARD GARDNER
on the idea behind his theory about several intelligences.HA
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74 | SCIENCE ILLUSTRATED
HUMANS INTELLIGENCE