Educability-and-Group-Differences-1973-by-Arthur-Robert-Jensen

288 Educability and Group Differences
The ‘better-designed* studies referred to are the two unpublished
studies (Theunissen, 1948; Falmagne, 1959); they report no evidence
of infant motor precocity in their African samples (which were from
different parts of Africa than those of other studies). I have not had
the opportunity to examine these unpublished theses at first hand, but
it is interesting that, as the only studies which have not reported
advanced development in Negro infants, Warren seems to regard
them as the only studies which are methodologically sound. I do
not concur in this conclusion. Though many of the other studies
surely cannot be held up as methodological paragons of rigorous
measurement and statistical inference, the striking magnitude of the
differences observed and the great consistency of the many studies
by different investigators using various techniques lends a weight
to the preponderance of evidence which cannot be dismissed by
two studies, whatever their methodological excellence, based on
different African subpopulations. In such a case, the difference in
results is much more likely due either to sampling differences or to
true subpopulation differences, rather than to methodological faults
which would have caused all other studies to yield opposite conclusions.
One almost wonders if Dr Warren’s rather extreme weighting
of the evidence toward the weakest possible conclusion is an illustration
of Bertrand Russell’s remark that ‘an intransigent perfectionism
is the last refuge of the skeptic’.
It seems apparent that the overall consistency and convergence of
many lines of evidence which point in the same direction must have
been largely ignored by Dr Warren in summarizing his conclusions.
He does not mention studies (e.g., Naylor & Myrianthopoulos, 1967;
Harrison, Weiner et al.y1964, p. 347; Nelson & Dean, 1959) which
show Negro infants’ advanced development in physical characteristics
such as rate of bone development (determined from X-rays showing
the rate of ossification of cartilage), the earlier eruption (by an
average of one year) of the permanent teeth, and the greater maturity
of brain wave patterns seen in electro-encephalograms. Nor is there
mention of those American studies, with the exception of Bayley’s
(1965), which are methodologically sound and more sophisticated
than most of the African studies (Pasamanick, 1949; Knobloch &
Pasamanick, 1953; Williams & Scott, 1953; Durham Education
Improvement Program, 1966-7a, b), and all of which report advanced
motor development of Negro as compared with white infants.
Of all existing studies, including the unpublished studies referred
to by Dr Warren, Bayley’s (1965) is based on the largest (1,409
infants) samples of Negroes and whites (and also the most representative
of the U.S. Negro and white populations). The standardization
and carefulness of testing procedures and the complete adequacy of