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

Culture-biased Tests 297
land in the city cost more than land in the country’ ‘Why are
laws necessary’) (Shuey, 1966, p. 407; Plotkin, 1971, p. 6). Negroes
actually score lowest on the Block Design subtest, a non-verbal
test requiring the subject to copy patterns of increasing complexity
with a set of sixteen colored one-inch blocks. This is probably
the least culture-loaded subtest of the WAIS. This is not a result
peculiar to the Wechsler tests. In general, Negroes obtain higher
scores on tests which by any reasonable criteria appear to be more
culture-loaded than on items that are less culture-loaded.
This has been demonstrated most dramatically in a study by
McGurk (1953a, 1953b, 1967). He compared the performance of
Negro and white 18-year-old high school students on highly
culture-loaded as compared with minimally culture-loaded intelligence
test items. For this purpose, to quote McGurk (1967,
p. 374), ‘A special test was constructed, half the questions of which
were rated as depending heavily on cultural background (the
culture questions) while the other half were rated as depending
little on cultural background (the non-cultural questions). Each
set of questions yielded a score - either a culture score or a nonculture
score.’ McGurk found that the ‘Negroes performed better
(relative to the whites) on the culturally loaded questions’ (p. 378).
This comparison was based on Negro and white groups selected
in such a manner that ‘Negroes and whites were paired so that the
members of each pair - one Negro and one white - were identical
or equivalent for fourteen socio-economic factors’ (p. 379).
How can we understand such seemingly paradoxical results,
which are the rule and not the exception In order to find the
answer, I have carried out item analyses of many kinds of intelligence
tests, seeking those which discriminate the most and the
least between Negro and white subjects, as well as between white
lower and middle SES subjects. When one brings together large
numbers of test items solely on the basis of whether they discriminate
minimally or maximally between Negro and white (or low
and middle SES) samples, the answer to the paradoxical findings
becomes apparent. All intelligence tests are intentionally devised
so that the items vary in difficulty, usually beginning with the
easiest items and increasing gradually to the most difficult items.
Item difficulty is objectively defined simply in terms of the percentage
of the normative population that fails to give the correct
answer to the item.