Information
The Information subtest reflects two factors in the child’s development of language and knowledge. The richness of the child’s verbal environment during his development is reflected in the fund of knowledge. The ability to store that knowledge in long-term memory, recall it, and verbally express it is an individual ability that is measured by the Information subtest.
Similarities
In order to store language and information in long-term memory, humans use a process of categorization and conceptualization that develops from the concrete to the abstract. The Similarities subtest captures the child’s ability to mentally process verbal information, categorizing and conceptualizing information in the long-term memory store. Over the course of the child’s development, their conceptual skills progress from concrete to abstract reasoning, a process that is reflected in the Similarities subtest.
Vocabulary
The Vocabulary subtest reflects both the child’s knowledge of words and a higher order ability to categorize words by their meanings, to retrieve that information, and express it with verbal fluency. This is quite an advanced task that again demonstrates both the richness of the child’s language environment and his natural ability to process that language.
Comprehension
The Comprehension subtest is based on social comprehension, a skill that is deficient in many children with learning disabilities or ADHD. The social understanding that underlies the Comprehension subtest is greatly influenced by the environment. Ethical judgment may be lacking for a variety of reasons—intellectual, environmental, and emotional. For children with significantly weak comprehension subtest scores, direct instruction in social skills may be required. Again, the Comprehension subtest performance is related to the child’s ability to express himself verbally.
Block Design
A pure test of perceptual intelligence, Block Design is the only Perceptual subtest that factors heavily with overall intelligence. Block Design will give you a good clue to innate intellectual potential. However, Block Design is a visual-motor task and poor performance may be developmental or related to a motor deficiency.
Digit Span Subtest
The Digit Span subtest is often excluded from the WISC-III administration and is not required to obtain the IQ scores. It is included in an assessment of the factor known as Freedom from Distractibility. An examiner may use the Digit Span subtest to suggest a possible ADD/ADHD diagnosis, particularly if it correlates with the other Freedom from Distractibility subtests—Arithmetic and Coding. High Digit Span scores suggest a superior ability to concentrate and memorize orally presented information.
Coding
An interesting performance subtest that measures visual-motor skill, Coding gives clues to basic deficiencies in visual-motor performance needed for writing. Good short-term memory improves performance on coding. It also factors with freedom from distractibility and the ability to concentrate to accomplish a visual-motor task within time constraints.
Picture Completion
The skill reflected by the Picture Completion subtest is not visual acuity; it is visual discrimination. The child must look at the visual whole presented and analyze its parts to identify what is missing. A relatively simple task, poor performance in a child with learning disabilities may be related to visual-perceptual difficulties or environmental awareness. Note that Picture Completion is eliminated in the WISC-IV.
Picture Arrangement
More complicated than Picture Completion, excellent performance requires a confluence of visual perceptual ability, social understanding, and higher-order thinking and planning. A weakness on the Picture Arrangement subtest may suggest a deficiency in one or all of these abilities. Note that Picture Arrangement is eliminated in the WISC-IV.
Object Assembly
The Object Assembly subtest score reflects the visual-motor skills of puzzle construction. The child must analyze the object and construct the whole visual object from its parts within time constraints. Note that Object Assembly is eliminated in the WISC-IV.
