102 PRETEND INTELLIGENCEBut the web of correlations merely redescribes the class structure and
social history of society and its unfortunate consequences.IQ IS NOT FIXEDSuch fatalistic views presuppose IQ to be a mea sure of a stable and du-
rable trait— the cognitive strength, or level of g—of individuals. IQ levels
are expected to stick to people like their blood group or height. But imag-
ine a mea sure of a real, stable, bodily function of an individual that is
diff er ent at diff er ent times. You’d prob ably think what a strange kind of
mea sure. IQ is just such a mea sure.
Of course, there is a modest average correlation of IQs at one age
with IQs at a later age, depending on the gap between mea sure ment
times. Th is may be no more than a mea sure of the degree to which
individuals’ circumstances have remained unchanged. Exactly the same
may be said about language dialect, or personal antibody profi les, for
example. But longitudinal studies have shown just how much IQs can
change across generations, as in the Flynn eff ect, but also for individu-
als as they age.
Carol Sigelman and Elizabeth Rider reported the IQs of one group of
children tested at regular intervals between the ages of two years and
seventeen years. Th e average diff erence between a child’s highest and low-
est scores was 28.5 points, with almost one- third showing changes of
more than 30 points (mean IQ is 100). Th is is suffi cient to move an indi-
vidual from the bottom to the top 10 percent or vice versa. In a 2011 re-
port, Sue Ramsden and colleagues showed how individual IQs in the
teenage years, in their sample, varied across the mean between minus 18
to plus 21, with 39 percent of the total sample showing statistically sig-
nifi cant change. What a strange mea sure indeed!^37
Consistent with such observations is the frequent demonstration of the
trainability of IQ. Test per for mance improves with practice, even on the
so- called tests of pure g, like the Raven, usually expected to be the most
experience free and therefore most stable. For example, Susanne Jaeggi
and colleagues trained adults on memory tasks, requiring the ability to
hold and manipulate information in the mind for a short period of time.
This content downloaded from 139.184.14.159 on Tue, 17 Oct 2017 13:52:12 UTChttp://www.ebook3000.com