Scattering Of Successes
It is sometimes a source of concern to the untrained examiner that the successes
and failures should be scattered over quite an extensive range of years. Why, it
may be asked, should not a child who has 10-year intelligence answer correctly all
the tests up to and including group X, and fail on all the tests beyond? There are
two reasons why such is almost never the case. In the first place, the
intelligence of an individual is
rdinarily not even. There are many
different kinds of intelligence, and in some of these the subject is
better endowed than in others. A second reason lies in the fact that no
test can be purely and simply a test of native intelligence. Given a
certain degree of intelligence, accidents of experience and training
bring it about that this intelligence will work more successfully with
some kinds of material than with others. For both of these reasons there
results a scattering of successes and failures over three or four years.
The subject fails first in one or two tests of a group, then in two or
three tests of the following group, the number of failures increasing
until there are no successes at all. Success "tapers off" from
100 per cent to 0. Once in a great while a child fails on several of the
tests of a given year and succeeds with a majority of those in the next
higher year. This is only an extreme instance of uneven intelligence or
of specialized experience, and does not necessarily reflect upon the
reliability of the tests for children in general. The method of
calculation given above strikes a kind of average and gives the general
level of intelligence, which is essentially the thing we want to know.