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Racial Differences in IQ but Not in Intelligence
Let us now consider how the definition of intelligence as processing can aid
in answering the question of what causes differences in IQ among groups of
people. Theoretically, the answer depends on whether group differences in processing
accompany group differences in IQ. I would assume that in the absence
of processing differences among groups, differences in IQ are most likely due to
cultural influences.
We are also aided in understanding group differences in IQ by noting those
that must be due to culture. Schooling effects are a clear instance of group
differences in IQ that must be due to the presence of differences in the culture's
provision of information. A comprehensive review of the extent to which various
factors associated with schooling have their effects on IQ is provided in Ceci
(1991). I focus on studies of children who were born just before or just after an
arbitrary cutoff date for school entry. The fact that one was born before or after
an arbitrary date obviously has nothing to do with either one's genetic plan or with
the physical effects of the environment on the brain (i.e., with factors that
influence processing). But being born before or after a particular date may have
a great deal to do with whether a child is in the fourth or the fifth grade by the age
10 and, consequently, with how much that child has been taught by the age of 10.
Cahan and Cohen (1989) conducted the archival study of the effects of cutoff dates for school entry on intelligence test scores. They administered portions of 12
different standard IQ tests to over 11,000 fourth, fifth, and sixth graders attending
the state-administered elementary schools in Jerusalem in 1987. The results were
unambiguous. Schooling affected raw intelligence test scores on all 12 tests,
including the Raven Progressive Matrices (Raven, Court, & Raven, 1975). I
mention the Raven test because it is highly g loaded (Jensen, 1993a) and, by
implication, has been thought not to be subject to cultural influence. Cahan and
Cohen (1989) have concluded that schooling is the major reason that intelligence
test scores increase with age.
As one might expect, schooling effects owing to cutoff dates have also been
found for other tests of knowledge such as reading and mathematics (Morrison,
Griffith, & Alberts, 1997). Schooling effects, however, have also been found for
tasks that one would usually consider to be elementary cognitive tasks and
unlikely to be subject to cultural influences. Cognitive tasks influenced by
schooling include phonetic segmentation (Bentin, Hammer, & Cahan, 1991;
Morrison, Smith, & Dow-Ehrensberger, 1995), short-term recall (Ferreira &
Morrison, 1994; Varnhagen, Morrison, & Everall, 1994; Morrison et al., 1995),
and mental arithmetic (Bisanz, Morrison, & Dunn, 1995). Tasks that appear to be
tests of processing are subject to schooling effects. Hence, the definition of
processing must be derived from a theoretical understanding of the task in
question and not simply assumed on the basis of the superficial characteristics of
the task. I return to the discussion of cultural influences on what appear to be
elementary cognitive tasks as I discuss racial differences in IQ. For the moment,
however, bear in mind that schooling effects provide a clear example of the
influence of a cultural factor on what are conventionally designated as tests of
intelligence, achievement, and basic cognitive functioning. Schooling effects must
reflect the influence of the culture on what one knows. Thus, tasks affected by
schooling must be, to some degree, culturally influenced.
Racial differences in IQ are a prime example of the application of the
procedural guideline that I suggest for the determination of group differences in
IQ. Differences in average IQ between Blacks and Whites on the order of about
1 standard deviation (about 15 IQ points) are well documented (Jensen, 1985) and
are present as early as 3 years of age (Fagan & Monfie, 1988; Peoples, Fagan, &
Drotar, 1995). I make no attempt here to trace the history of the arguments that
have been made for the causes of racial differences in IQ. The interested reader
may consult the historical discussions contained in Block and Dworkin (1976) or
the references cited by Neisser et al. (1996). Suffice it to say that there are those
who lean toward a genetic explanation and those who favor a cultural explanation
of Black-White differences in IQ.
I accept the evidence for IQ differences between Blacks and Whites at face
value. Theoretically, I ask if the presence of racial differences in IQ is accompanied
by differences between Blacks and Whites on measures of the spontaneous
processing of information. If so, the search for the causes of Black-White
differences in IQ should be directed toward genetic or physical environmental
factors. If not, the search should concentrate on cultural influences.
As I noted in my discussion of schooling effects on IQ, performance on some
elementary cognitive tasks may be culturally influenced. Thus, one must be
cautious in attributing racial differences in IQ to processing differences on the basis of any or all cognitive tasks. A case in point is the study reported by Jensen
(1993b) of 585 White and 235 Black schoolchildren whose reaction times were
measured on what appeared to be simple information-processing tasks. Jensen
used four tasks, which varied in the time taken for successful solution. The easiest
task was a simple reaction time task in which the time taken to lift one's finger
from a home key on presentation of a signal from a single source was measured.
A slightly more demanding task measured the same reaction times when the
signal to respond came from any one of eight sources. In a more complex
discrimination task, reaction time was measured when three signals (out of eight)
were activated at once and the child had to decide which of the three was located
at the greatest distance from the other two before reacting. The most demanding
task was the measurement of reaction times over a series of mental arithmetic
problems involving addition, subtraction, or multiplication of single-digit
numbers.
Jensen's results (taken from the data given by Jensen, 1993b, in his Appendices
A and B) indicated that mean reaction times for Blacks and Whites did not
vary on the two simple tasks but did differ on the two more demanding tasks. As
noted in the summary of schooling effects, age of school entry alters performance
on tests of short-term memory and the speed of solution of mental arithmetic
problems. Thus, the present theory suggests that the pattern of Jensen's (1993b)
results may actually indicate the influence of a cultural factor on the performance
differences of Blacks and Whites. The suggestion of the present theory as the
reason for Jensen's results could easily be checked by using Jensen's four reaction
time tasks in a study of children (of the same race and the same age) whose
birthdates fall just before or just after an arbitrary cutoff date for school entry. If
children of the same age who varied in schooling did not differ on Jensen's simple
tasks but did differ on Jensen's more demanding tasks, it would mark the more
demanding tasks (but not the simple tasks) as subject to cultural influences. The
cultural factors affecting Black-White differences, of course, may not be the same
as those influencing schooling effects.
In my own program, I have obtained IQ scores for 299 preschoolers at 3 years
of age, who, as infants, were tested for attention to novelty. Attention to novelty
is a processing task that does not vary for children of various school ages and is
applicable from birth to senescence (Fagan & Haiken-Vasen, 1997). Of the 299,
35 children were Black, and 264 were White. All came from middle-class,
suburban homes. Their parents, as a group, did not differ in level of education. In
addition, I participated in a multisite, national study of 70 high-risk infants (34
White and 36 Black) from predominantly lower-class families, who were tested
for visual attention to novelty as infants and for IQ on the Bayley Scales of Infant
Development (Bayley, 1969) at 2 years of age (Fagan & Shepherd, 1992). Finally,
as part of a dissertation by Haiken-Vasen (1995), we tested 96 schoolchildren (64
Black and 32 White), with a mean age of about 9 years (SD = 2.6), who were
attending church-affiliated schools. The schoolchildren were tested for both visual
attention to novelty and, on the Peabody Picture Vocabulary Test (Dunn & Dunn,
1981), for IQ. The specific procedures for testing the visual novelty preferences
of older children and adults are given in Fagan and Haiken-Vasen (1997). With
the exception of briefer study times, however, testing of attention to visual novelty.
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