Race and Intelligence

Type of psychology: Biological bases of behavior; intelligence and
intelligence testing
Fields of study: Biological influences on learning; general issues in
intelligence; intelligence assessment
The relationship between race and intelligence has long been the subject of heated debate
among social scientists. At issue is whether intelligence is an inherited trait or is
primarily attributable to environmental influences.
Key concepts
• intelligence quotient (IQ) tests
• nature versus nurture
• twin studies
In 1969, educational psychologist Arthur Jensen published an article in the
Harvard Educational Review titled “How Much Can We Boost I.Q. and Scholastic
Achievement?” He attempted to explain multiple findings that whites,
on the average, outperform blacks by about 15 points on intelligence quotient
(IQ) tests. His major conclusion was that racial differences in intelligence
are primarily attributable to heredity and that whites, as a racial
group, are born with abilities superior to those of blacks.
Jensen, as well as William Shockley, presents the hereditarian hypothesis
of intelligence. It argues that some people are born smarter than others and
that this fact cannot be changed with training, education, or any alteration
in the environment. Because they believe that African Americans as a group
are not as smart as Caucasians, they suggest that special programs, such as
Head Start, which are designed to help disadvantaged children improve in
school achievement, are doomed to fail.
In contrast to the hereditarians, Urie Bronfenbrenner and Ashley Montagu
can be described as environmentalists. They believe that although intelligence
has some genetic component, as do all human characteristics, the
expression of intelligent behavior is defined, determined, and developed
within a specific cultural context. Therefore, what people choose to call intelligence
is primarily caused by the interaction of genetics with environmental
influences. Environmentalists believe that a person can improve in
his or her intellectual functioning with sufficient changes in environment.
Richard Herrnstein and Charles Murray’s The Bell Curve (1994) reopened
the issue of heredity versus environment in the attainment of intelligence.
The authors argue that Caucasians are inherently superior to African
Americans in IQ levels, presenting a mass of statistical evidence to support
their position. Critics of The Bell Curve attack it on a number of fronts. There
is a failure to separate hereditary from genetic variables. The definition of
race proves a difficult one. The IQ tests themselves come into the same culture
bias category. The statistical tests hide more than they reveal. There is
difficulty replicating Hernnstein and Murray’s results. The defects mount
up rather quickly.
Much of the hereditarian argument is based on two types of studies: those
comparing IQ test performances of twins and those of adopted children. Because
identical twins have the same genetic endowment, it is thought that
any differences observed between them should be attributable to the effects
of the environment. Hereditarians also suggest that one should observe
more similarities in the IQs of parents and their biological children (because
they share genes) than between parents and adopted children (who
are biologically unrelated and therefore share no genes).
Statistical formulas are applied to comparisons between family members’
IQs to determine the relative contributions of heredity and environment.
Using this method, Sir Cyril Burt in 1958 reported a heritability estimate of
.93. This means that 93 percent of the variability in intelligence could be explained
genetically. People have also interpreted this to mean that 93 percent
of the intelligence level is inherited. Jensen has more recently reported
heritability estimates of .80 and .67, depending on what formula is used.
Hereditarians have also pointed out that when they compare African Americans
and Caucasians from similar environments (the same educational
level, income level, or occupation), the reported IQ differences remain.
This, they argue, supports their view that heredity is more important than
environment in determining intelligence. The same arguments have been
made for the work of Hernnstein and Murray.
For environmentalists, it is not so much the reported IQ differences between
different racial groups that are in question. Of more concern are the
basic assumptions made by the hereditarians and the reasons they give for
the reported differences. Not surprisingly, environmentalists challenge the
hereditarian arguments on several levels. First, they point out that there is
no evidence of the existence of an “intelligence” gene or set of genes. They
say that scientists have been unsuccessful in distinguishing the genetic from
the environmental contributions to intelligence.
Environmentalists also refute the assumption that IQ tests adequately
measure intelligence. Although IQ has been noted to be a good predictor of
success in school, it turns out to have little relationship to economic success
in life. S. E. Luria reports an analysis that shows that the son of a Caucasian
businessman with an IQ of 90 has a greater chance of success than an African
American boy with an IQ of 120. This example calls into question what
actually is being assessed. It is not at all clear that “intelligence” is being measured—
especially as there is no generally accepted definition of intelligence
among social scientists.
The definition of race is also problematic. Although most people may
identify several racial groups (such as African, or black; Caucasian, or white;
and so on), Montagu and many other social scientists agree that race is a
pseudoscientific concept, used as a social or political category to assign social
status and to subordinate nonwhite populations. Because of intermingling among different cultural groups, it is also difficult to identify strict biological
boundaries for race, which in turn makes genetic interpretations of
racial comparisons of IQ differences much less meaningful.
In addition to questioning what IQ tests measure, many psychologists
have criticized IQ tests as being biased against individuals who are culturally
different from the mainstream group (Caucasians) and who have not assimilated
the white, middle-class norms upon which the tests were based. Tests
developed in one culture may not adequately measure the abilities and aptitude
of people from another culture, especially if the two cultures emphasize
different skills, ways of solving problems, and ways of understanding the
world.
Environmentalists have also criticized the research and statistical techniques
used by the hereditarians. It is now widely acknowledged that the
data reported by Burt, upon which Jensen heavily relied, were false. In many
different studies, he came up with the same figures (to the third decimal
point) for the similarities between IQ scores for twins. This is statistically impossible.
He also did not take into account how other variables, such as age
and gender, might have produced higher IQ values in the twins he studied.
Rather, he assumed that they shared genes for intelligence.

It is also charged that the concept of heritability is misunderstood by the
hereditarians. This is a statistic that applies to groups, not to individuals. If
one states that the heritability estimate of a group of IQ scores is .80, that
does not mean that 80 percent of each IQ score is attributable to genetics,
but that 80 percent of the difference in the group of scores can be attributed
to genetic variation. Therefore, according to the enviromentalists, it is incorrect
for hereditarians to establish heritability within one group (such as
Caucasian children) and then apply that figure to a different racial group
(such as African American children). 707