
True IQ
By Inderbir Kaur Sandhu, Ph.D
Q:
I have three children, identical twins 22, and one 16 all
boys. They were all diagnosed in school with learning
disabilities. The twins verbal IQ's were both 128 but
performance IQ was 95. Their disability was in auditory. My
youngest verbal IQ is 133 and performance IQ was 91. And he
has disability in visual.
What is the true IQ? Is it the higher number or somewhere in
between? Incidentally, the Twins both go to Art Center
College of Design in Pasadena and are considered very
gifted. I'm struggling getting the youngest one through high
school.
A: To date, there is no test
that can actually predict true IQ. IQ scores are the best
possible approximation to predict one's cognitive ability
based on what is being tested. In fact it is indeed easier
to make an IQ score that is lower than one's true IQ than it
is to make a score that is higher. For example, taking a
test on a bad day, or spending too much time on a few
difficult items could actually artificially lower one's
score. The best results are obtained when more than one test
is administered.
In general, learning disability may be diagnosed when an individual's
potential (IQ) differs significantly from their achievement.
The measurement may be lower than his true IQ because of the
test's inability to account for impairment on the part of
the taker. For someone who is learning disabled, a good
diagnosis takes a minimum of six hours, preferably 8 to10 by
a trained psychologist. It consists of an intelligence test
and an achievement test. This is really where it starts. The
IQ score should not be influenced by the presence of
learning disability.
People with learning disability often have a score profile where, for
example, they score high on the math, but low on the verbal
parts of the test. The diagnostician should then, based on
that profile, select another IQ test (for example, a
non-verbal one) that is insensitive to the presumed
disability (in your son's case, visual disability), in order
to get a reliable estimate of the "true" IQ. Your son's
verbal scores are above average, and he may be gifted. You
did not indicate the problems he faces at school, hence you
may want to speak to a school authority (perhaps a school
counselor if his problem is emotionally linked) on how best
to help your son.
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