Low Scores in WISC IV Processing Speed
By Inderbir Kaur Sandhu, Ph.D
We have a 6 year old son recently tested WISC IV:
|Full Scale IQ
Processing speed seems to be the "odd one out"
1. Does this make sense, or could it be an artifact of
motivation, and the test administration, which was done by
someone experienced with low functioning kids, but certainly
not with gifted kids.
My son used to have a tremendous eagerness to learn. Last
summer he was adding 5 digit numbers in his head for
entertainment. He started K last September and has been
noticeably disappointed in the "math" classes, and lack of
science teaching, which he had expected. He has verbalized
this in a dejected tone of voice. I feel he is bored and is
recently becoming oppositional.
He increased his reading rapidly in the past year, and now
reads about one chapter book (currently, the Andrew Lost
series) per day. He is able to tell about what he read.
2. Is rapidly learning to read, with good comprehension,
compatible with slow processing speed?
3. Two years ago, he completed a number of Lego Technic
structures; these are intended for 9-12 year olds and
include a thick instruction manual and hundreds of pieces.
He completed these in a number of hours each, working for an
hour at a time, intensely, and without assistance. He used
to cut out outlines of jet planes (with correct details of
tail shape etc) or animals with quite remarkable dexterity,
quickly moving the scissors around the finer parts of the
outline. He has used scissors on his own for years.
Are these skills compatible with slow processing speed?
I feel he has become de-motivated at his school. They have
steadfastly omitted to give him more challenging questions
in math, for example (his math class consists of adding
single digit numbers). However, the teacher pointedly
related that he was unable to immediately apply his math
skills to a problem which she asked him out loud, as part of
a class project.
At home he enjoys doing long multiplication now (three digit
numbers), and simple algebra e.g:
10 + 2n = 20
9 + 3n + 4n + 3 = 26
At first he tries to arrive at the answer in one fell swoop,
but realized after some stubbornness that it is more
effective to write out the working line by line.
Is this stubbornness a function of low processing speed or
just that he feels he should be able to do it his way?
We are very much in need of help. Thank you so much.
A: Processing speed generally
refers to the varying speed with which individuals are able
to perform cognitive activities such as the recognition of
simple stimuli. Higher speed in cognitive processing usually
allows more information to be acquired in a shorter time
span enabling the individual to absorb and master materials
of higher levels. Above average individuals usually have
high processing speed, thus enabling them to reach
developmental milestones ahead of their age mates. In
layman’s terms, the brain is working faster which is viewed
as superior intelligence, hence the difference in human
Having said that, there is more to intelligence than speed
of processing, which is the reason most IQ test use a
combination of factors to assess intellectual skills.
According to the WISC, processing speed measures children's
abilities to focus attention and quickly scan, discriminate
between, and sequentially order visual information. It
requires persistence and planning ability, but is sensitive
to motivation, difficulty working under a time pressure, and
motor coordination too. Cultural factors seem to have little
impact on it. It is related to reading performance and
development too. It is related to Working Memory in that
increased processing speed can decrease the load placed on
working memory, while decreased processing speed can impair
the effectiveness of working memory.
In the case of your son, given your description, the PSI
should have been higher. However, there may be other factors
influencing the scores. It may be due to motivation but
unlikely the test administration. Bear in mind that
processing speed accounts for only 23% of the variance in
general intelligence. Is there any indication of ADHD – the
inattentive type? Apparently, lower processing speed scores
could indicate such concerns. There are children with ADHD
who have IQ scores in the gifted range, yet rather low
processing speed. The WISC scores alone are not able to make
that diagnosis. However, this may not even be the case for
your son as his attention appears to be stable enabling him
to accomplish tasks that you mentioned.
It is best that you speak to the tester regarding the
interpretation of the scores. Based on the full report and
breakdown of the scores (especially for coding), s/he may be
able to help. If you are not satisfied with the explanation,
look for someone experienced in testing gifted children who
may be able to interpret the results better. Good luck!
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Dawn P. Flanagan Ph.D, Alan S. Kaufman Ph.D
The WISC-IV is the top intelligence assessment instrument
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