Wechsler Intelligence Scale for Children - III

by Lizette Campbell (Child and Educational Psychologist) | Disclaimer

The Wechsler Intelligence Scale for Children-III (WISC-III) is a battery of tests for 6 to 17 year olds that evaluates intellectual abilities. The WISC-III consists of two scales, the Verbal Scale and the Performance Scale. Each of these scales has several subtests.

The Verbal Scale measures language expression, comprehension, listening, and the ability to apply these skills to solving problems. The examiner gives the questions orally, and the child gives a spoken response. The Performance Scale assesses nonverbal problem solving, perceptual organisation, speed, and visual-motor proficiency. Included are tasks like puzzles, analysis of pictures, imitating designs with blocks, and copying.

Several scores are obtained from the WISC-III. Scale scores (Verbal and Performance IQ scores) are the summary measures of verbal and performance skills, and the Full Scale IQ is an index of general intellectual functioning.

Factor scores and subtest combinations show other indices of cognitive ability. These scores may provide additional hypotheses about learning style and factors underlying scores on the WISC-III. Scale, factor, and subtest scores show strengths and weaknesses when compared to other young people of the same age or to the student's own pattern of development.

A typicial report summary may look like:

IQ Scale / Index	IQ Scale Score	Percentile	Confidence Interval	Range
Verbal IQ
Performance IQ
Full Scale IQ
Verbal Comprehension Index
Perceptual Organisation Index
Freedom From Distractibility Index
Processing Speed Index

Test scores change over time due to chance, error, and many other factors. A Percentile rank expresses the relative position of a score. For example, a percentile rank of 98 means that a child has scored as well as or better than 98% of students of the same age on that subtest. The confidence interval indicates the probable range of scores which can be expected when this individual is retested. Subtest scaled scores (listed below) range from 1 to 19.

	Scaled Score	%ile Rank	Description
Verbal Subtests
Information			General factual knowledge, long term memory
Similarities			Abstract reasoning, categories, relationships
Arithmetic			Attention, concentration, numerical reasoning
Vocabulary			Word knowledge, verbal fluency
Comprehension			Social judgement, common sense reasoning
Digit Span			Short term auditory memory, concentration
Performance Subtests
Picture Completion			Alertness to essential detail
Coding			Visual motor co-ordination, speed, concentration
Picture Arrangement			Sequential, logical thinking
Block Design			Spatial, abstract visual problem solving
Object Assembly			Visual analysis, construction of objects
Symbol Search			Speed of processing novel information
Mazes			Fine motor co-ordination, planning, following directions

Intelligence tests like this one are samples of problem solving abilities and learned facts, and are good predictors of future learning and academic success. However, there are several factors that the tests do not measure. For instance, they cannot determine motivation, curiosity, creative talent, work habits, study skills, or achievement in academic subjects. These should also be considered when interpreting the scores in this report.

Disclaimer:

The information provided is intended to give parents an overview of the Wechsler Scales and how they are used to assess children. The Wechsler tests form one part of an assessment, and other measures may include an early developmental history, formal and informal observation of the child, academic skills testing, measures of personality, emotional and social development, examination of the child's creative and school interests and so on.

It is important to discuss any questions relating to your child's assessment with the psychologist who performs the assessment as they can put the test results and observed behaviours into context with their knowledge of the different tests and of child development. It is also important to realise that, as every child is unique, there cannot be a "recipe" type approach to interpreting their scores or results. This is particularly true of isolating one or two subtest scores.

 © NSWAGTC 2007

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