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

76 Educability and Group Differences
One of the most impressive characteristics of intelligence tests is
the great diversity of means by which essentially the same ability
can be measured. Tests having very diverse forms, such as vocabulary,
block designs, matrices, number series, ‘odd man out’, figure
copying, verbal analogies, and other kinds of problems can all
serve as intelligence tests yielding more or less equivalent results
because of their high intercorrelations. All of these types of tests
have high loadings on the g factor, which, as Wechsler (1958, p.
121) has said, ‘. . . involves broad mental organization; it is
independent of the modality or contextual structure from which it
is elicited; g cannot be exclusively identified with any single
intellectual ability and for this reason cannot be described in
concrete operational terms’. We can accurately define g only in
terms of certain mathematical operations; in Wechsler’s words,
lg is a measure of a collective communality which necessarily
emerges from the intercorrelation of any broad sample of mental
abilities’ (p. 123).
Assessment of scholastic achievement, on the other hand, depends
upon tests of narrowly specific acquired skills - reading, spelling,
arithmetic operations, and the like. The forms by means of which
one can test any one of these scholastic skills are very limited
indeed. This is not to say that there is not a general factor common
to all tests of scholastic achievement, but this general factor common
to all the tests seems to be quite indistinguishable from the
g factor of intelligence tests. Achievement tests, however, usually
do not have quite as high g loadings as intelligence tests but
have higher loadings on group factors such as verbal and numerical
ability factors, containing, as well, more content-specific
variance.
It is always possible to make achievement tests correlate more
highly with intelligence tests by requiring students to reason, to
use data provided, and to apply their factual knowledge to the
solution of new problems. More than just the mastery of factual
information, intelligence is the ability to apply this information
in new and different ways. With increasing grade level, achievement
tests have more and more variance in common with tests of g.
For example, once the basic skills in reading have been acquired,
reading achievement tests must increasingly measure the student’s
comprehension of more and more complex selections rather than
the simpler processes of word recognition, decoding, etc. And thus