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

314 Educability and Group Differences
‘bigger’, he actually believes the quantity of clay has been increased;
and similarly when he sees liquid poured from a shallow,
broad bowl into a tall, slender flask. There are many ways that
the concept of conservation shows up: in number, length, area,
time, weight, volume, and so on. Piaget has invented means for
assessing children’s conservation concepts in all these forms, along
with many other tests and procedures for studying the sequence
of mental development throughout each of its main stages.
Now, what have child psychologists learned from the application
of Piaget’s tests that is relevant to Voyat’s commentary
First, Voyat is probably correct in his opinion that the Piagetian
tests are less culture-bound than conventional IQ tests. For one
thing, some groups reared under environmental conditions which
are extremely different from those of Western culture have been
found to show not only the same sequence of development through
Piaget’s stages, but are even somewhat more accelerated in this
development than white middle-class children. Again, Arctic
Eskimos were found to excel over white urban Canadian children
in the Piagetian tests, and Canadian Indians do almost as well as
the Eskimos (Vernon, 1965b; MacArthur, 1968, p. 48). Obviously
it is not necessary to have lived in a Western or middle-class
culture in order to perform up to Western middle-class levels on
Piagetian tests.
In rank-ordering children of the same chronological age in
terms of their rate of mental development, the Piagetian tests are
not very different from other culture-reduced tests. Vernon (1965b)
factor analyzed a large number of Piagetian tests along with
conventional psychometric measures of intelligence and found
that the Piagetian tests were heavily loaded on g, the general
factor common to all intelligence tests. In fact, the Piagetian tests
measured little else than g; the non-g variance seems to be taskspecific,
i.e., it has nothing in common with other Piagetian tests
or with conventional IQ tests. Tuddenham (1970) gave a battery
of Piagetian tests, along with Raven’s Matrices and the Peabody
Picture Vocabulary Test (PPVT), to a large number of elementary
school children, and concluded: ‘. . . the Raven has the higher
correlations, ranging from 0-24 to 0-50, as compared with Peabody
values of 0-13 to 0-37 for a similar though not identical set of
Piagetian items’ (p. 68). These are relatively high values for single
item correlations within a restricted age range. Tuddenham notes