different responses, the test data may not be very
useful. In some instances, clients may remember on
the second occasion their responses from the first
time. Or they may develop a kind of “test-
wiseness” from the first test that influences their
scores the second time around. In still other cases,
clients may rehearse between testing occasions or
show practice effects. For all these reasons, another
gauge of reliability is sometimes used—equivalent-
forms reliability. Here, equivalent or parallel forms of
a test are developed to avoid the preceding problems.
Sometimes it is too expensive (in time or money)
to develop an equivalent form, or it is difficult or
impossible to be sure the forms are really equivalent.
Under such circumstances, or when retesting is not
practical, assessingsplit-half reliabilityis a possibility.
Thismeansthatatestisdividedintohalves(usually
odd-numbered items versus even-numbered items),
and participants’scores on the two halves are com-
pared. Split-half reliability also serves as one possible
index of a test’sinternal consistency reliability.Do the
items on the test appear to be measuring the sameBOX7-1 The Bell CurvePerhaps no other psychology book in recent times has
generated as much controversy as Herrnstein and
Murray’s (1994)The Bell Curve. Briefly, Herrnstein and
Murray argue that, since the 1960s, the United States
has become increasingly divided based on the cognitive
or intellectual ability of its citizens. What has emerged
is a class labeled the“cognitive elite”who are primar-
ily concentrated in a small group of occupations (e.g.,
doctors, lawyers, professors) that essentially screen for
high IQ. Although intelligence is a product of both
genetic and environmental factors, our country’s
attempt to“equalize”the environment for all (i.e.,
give everyone the same opportunities to succeed)
ironically leads to a situation in which the genes we
inherit are the primary source of individual differences.
In a sense, Herrnstein and Murray contend, this will
only serve to widen the gap between the haves and
the have-nots in coming generations. The authors also
present evidence supporting their position that cogni-
tive ability/intelligence is the most important predictor
of outcomes such as financial stability, success in col-
lege, welfare dependence, producing“illegitimate”
children, and criminal behavior. They also review the
data on ethnic/racial differences in IQ and argue that
efforts to raise IQ scores through educational programs
or programs such as Head Start have not produced
positive long-term effects. Finally, Herrnstein and
Murray provide a number of prescriptions for remedy-
ing the current disparity, including overhauling affir-
mative action policies for education and the workplace
as well as returning decision-making power to local
governing bodies.
Most of the negative reaction to this book
appears to be based on disagreement with the authors’
prescriptions for social policy and, at times, appears to
take the form of ad hominem arguments. In addition,some critics have taken issue with the methodology,
analysis, and interpretation of some of the empirical
studies cited and discussed in the book. On the other
hand, a group of experts in the field of intelligence
published a brief article in theWall Street Journal
(Arvey et al., 1994) that outlined“mainstream”con-
clusions among researchers on intelligence. Many of
the points made inThe Bell Curveare consistent with
these conclusions. The experts, however, stopped short
of prescribing social policy based on these conclusions.
Alderfer (2003) argues that psychologists have not
gone far enough in highlighting the limitations of the
empirical analysis presented inThe Bell Curve. Alderfer
remains unconvinced by the authors’“scientific argu-
ments,”including the heritability of intelligence as
well as the relations between IQ and social problems
(e.g., poverty, unemployment, welfare, imprisonment).
According to Alderfer, socioeconomic status is perhaps
the major contributing factor for racial differences in
IQ and is the third variable responsible for the appar-
ent association between IQ and social problems.
Therefore, he urges psychologists to focus their ener-
gies on combating injustices, including racism, that
lead to poorer achievement.
Finally, Sternberg et al. (2005) presented a series
of compelling arguments that highlighted the lack of
consensus, even today, as to the definition and mea-
surement of intelligence, as well as the fact that the
concept of“race”is actually a social construction
without biological or genetic basis. Furthermore, both
IQ scores as well as heritability estimates for intelli-
gence are highly variablewithinracial groups. There-
fore, the lack of precision in defining intelligence and
the great variability in estimates within groups limit
any conclusions that can be drawn regarding the rela-
tions between IQ and race and genetics.THE ASSESSMENT OF INTELLIGENCE 195