“Intelligence” is in quotes because it is a fraught subject
for technical and political reasons, raising issues of its
nature, how it is tested, and the uses of results. This
cursory overview is even less reliable than other pages
on this site.
Intelligence is meant to be a generalized measure of
overall ability, or potential ability: its proponents claim
that it is getting at an underlying feature which is independent
of specific skill development or learning achievement.
The problem is that it is difficult to get a consensus
about what "intelligence" actually is:
"The power of good responses from the
point of view of truth or fact" (Thorndike)
"A biological mechanism by which the effects
of a complexity of stimuli are brought together and
given a somewhat unified effect in behavior" (Peterson)
"The ability to carry on abstract thinking"
"The ability to adapt oneself adequately
to relatively new situations in life" (Pintner)
"The capacity for knowledge, and knowledge
"The capacity to acquire capacity"
"Viewed narrowly, there seem to be almost
as many definitions of intelligence as there were experts asked
to define it" (Sternberg 1987)
- Francis Galton (1884) measured head size, reaction
time etc., but found no correlations
- Alfred Binet (1905 on) devised tests to determine
ineducability (to meet the requirements of a new French
law prescribing schooling for all educable children)
and formulated the idea of "Mental Age" from
which developed the idea of the "Intelligence
Quotient" (see below)
- Lewis Terman (at Stanford University) adapted and
standardised the Binet tests for American children (1916,
and routinely revised since) known as the "Stanford-Binet"
- David Wechsler developed the Wechsler Adult Intelligence
Scale in 1939
Tests on the Net
Intelligence Quotient (IQ)
Mental Age x 100
So if the Mental Age = Chronological Age, IQ = 100, the
notional average. The distribution of IQ supposedly follows
a normal distribution curve (or "Bell Curve"),
and assessment of "superiority" and "inferiority"
is determined by the number of statistical Standard Deviations
above and below the mean.
However, the "Flynn effect" suggests
that IQ scores have been rising over time, so that the initial
norm of 100 is no longer valid. This is of course problematic
because of different approaches to measurement.
The Bell curve referred to in
and Murray's (1995) famous (or notorious) book is simply
the normal distribution curve which IQ tests were set up
to plot. 68% of the population come within one standard
deviation of the mean, and 95% within two standard deviations.
The 1986 Stanford-Binet Test —one of the accepted standard
tests—examines four broad areas of intelligence, which are
supposed to be independent of each other, and not
However, there is considerable argument as to whether
these are simply more specific manifestations of a more
general underlying feature, known as the g factor.
The g (for "general") factor is arrived
at by factor analysis of results from tests and is suggested
as the main underlying component, supplemented by components
relating to more specific aptitudes. Critics suggest g
is an artifact of method, since Spearman was a statistician
rather than a psychologist, although it is conceded that
“intelligence” may have a hierarchical structure.
At the other end of the scale is the notion of
intelligences, suggested by Howard Gardner.
Clearly, high intelligence may be expected
to correlate significantly with educational achievement.
The correlation is positive, but declines substantially
as students proceed through the system:
| Primary school
| College 0.4-0.5
Figures from US. terminology from
et al (1993)
Factors in Educational Achievement
As the correlation figures show, intelligence alone is
not sufficient to account for academic achievement: it is
certainly necessary, but beyond a certain threshold, it
is by no means clear how much.
As education progresses, other factors come into
play, such that the limits are determined by the strength
of the weakest link in the chain.
Intelligence has been a fraught political issue,
ever since Francis Galton attempted to measure ability
to support his eugenic theories. Early abuses in the
United States included compulsory sterilisation of people
with low IQ
- In the UK, Sir Cyril Burt's work on IQ was the basis
of selection at 11+, in the 1944 Education Act. In the
1970s, Burt was accused of fraudulent results because
some of his findings were too significant: he
appears to have been rehabilitated, but there are still
some unanswered questions.
- Arthur Jensen (1969) was accused of racism when
he suggested that white children were more intelligent
than blacks (and that Asian children were brighter than
either). Latterly, the controversy has been revived
by Herrnstein and Murray (1995) and publication of Chris
Brand's book The g Factor was abandoned
at the last minute in 1996 because of concerns about
his self-confessed "scientific racism"
For critical reviews of these issues see
There is considerable debate over the hereditary component
in intelligence, and the picture is getting more complicated
all the time, but at least one school believes that intelligence
can largely be identified with "problem-solving skills"
or even forms of pattern recognition and that as such it
can be taught. (Feuerstein,
more accessible account—
What does this mean in practical terms for teachers?
The construct of "intelligence" was the
most potent psychological notion affecting educational policy
in the last century. In 1958, in "The Rise of the Meritocracy,
1870-2033" Michael Young envisaged a world in which intelligence
was the sole determinant of status in society: re-reading it
today it sometimes seems quaint, but sometimes uncannily accurate
In practice, the label has been used mainly for labelling—whether
the unforgiving watershed of the 11+ exam in the UK, until the
introduction of the comprehensive system, or more currently
the application of "Atherton's law": "The amount
of attention paid to teaching and learning is in inverse proportion
to the perceived ability of the students." The discourse of
"bright" versus "thick" or "stupid"
still pervades the informal and unaccountable judgements of
teachers on students. It remains their traditional exculpatory
angle. But apart from that, what can you do with it?
For some people, it has been a life- (or at least career-)
saver: the discrepancy between this measure of potential and
those of achievement has shown that they were severely under-estimated.
Einstein is the classic case, but IQ was not an active factor
in his ignominious early career. On the other hand, its record
as a self-fulfilling prophecy outweighs this: the
and Jacobson study epitomises the issue.
(For the record: at age 14,
my score on the full Stanford-Binet battery was 158—but only
because I was able to persuade the tester that some of my answers
were just as valid as the standard ones. If he had been any
good, he would never have betrayed by his expression that some
of them were "wrong"! I've been suspicious ever since.)
Find it online at www.questia.com
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