Discrepancy in WISC IV Scores
By Inderbir Kaur Sandhu, Ph.D
My daughter is 11 and was recently tested using WISC IV Australian. She
scored Superior in PRI and PSI, average in WMI and VCI. In WIAT-II
Australian her Mathematics Composite score & Written Expression Skills
were at the 75th percentile. Reading Comprehension 70th, yet Word
Reading Accuracy 42nd and Spelling 25th. She also plays the piano at
AMEB level 7.
We had her tested because she is in the lowest English and Math classes
at school and we felt she was capable of more. We are now confused about
what these results demonstrate. Can you explain this to us?
It is important to understand what the various indexes indicate. The
following shows the four main indexes of the WISC-IV and what they
|Verbal Comprehension Index (VCI)
Measure: Verbal concept formation.
It assesses children's ability to listen to a question, draw
upon learned information from both formal and informal
education, reason through an answer, and express their thoughts
aloud. It can tap preferences for verbal information, a
difficulty with novel and unexpected situations, or a desire for
more time to process information rather than decide "on the
Note: This index is a good predictor of readiness for school and
achievement orientation, but can be influenced by background,
education, and cultural opportunities.
|Perceptual Reasoning Index (PRI)
||Measure: Non-verbal and fluid reasoning.
It assesses children's ability to examine a problem, draw upon
visual-motor and visual-spatial skills, organize their thoughts,
create solutions, and then test them. It can also tap
preferences for visual information, comfort with novel and
unexpected situations, or a preference to learn by doing.
|Working Memory Index (WMI)
||Measure: Working memory.
It assesses children's ability to memorize new information, hold
it in short-term memory, concentrate, and manipulate that
information to produce some result or reasoning processes. It is
important in higher-order thinking, learning, and achievement.
It can tap concentration, planning ability, cognitive
flexibility, and sequencing skill, but is sensitive to anxiety
too. It is an important component of learning and achievement,
and ability to self-monitor.
|Processing Speed Index (PSI)
||Measure: Processing speed.
It assesses 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.
It appears that your daughter scored in the superior range in PRI (for
non verbal and fluid reasoning) and PSI (for processing speed). The
average scores on VCI and WMI shows average ability in forming verbal
concept and holding and manipulating new information. With the limited
information given on the scores, what I suspect here is a probable
learning disability that may have gone undetected all this time. The
WISC can be used to detect a learning disability as it provides a
comprehensive diagnostic assessment of a child's educational and
cognitive strengths and weaknesses.
For VCI, it is more rewarding for a more responsive child so if your
child is not very responsive, she may lose a little here. The lower
scores are average and not extremely low, therefore it is best to see
the psychologist who did the testing to check the detailed scores and
determine the sub-areas that brought down the scores for a better
indication of extremities. It has been suggested that a 19 point
discrepancy in the VCI (or PRI) composites may warrant further
investigation. Again, detailed scores are required to determine any
further assessment. Please speak to the tester or see a psychologist who
is familiar with WISC IV with the detailed report. Good luck!