By David Wechsler
WAIS III (3rd Edition) has four composite scores
WAIS-III Subtests Grouped According to Indices
In addition to the Verbal and Performance IQ scores, the following four composite scores.
Full Scale IQ (FSIQ) is comprises of the four composite scores.
Verbal Comprehension Index (VCI): Requires verbal conceptualization, stored knowledge access and oral expression. Orally presented questions that assess common-sense reasoning, reasoning out or retrieving word associations, and the ability to describe the nature or meaning of words. Knowledge acquired from one's environment. Verbal expression required (length of response varies). One of the best predictors of overal intelligence.
Perceptual Organization Index (POI): Requires visual perception, organization and reasoning with visually presented, nonverbal material to solve the kinds of problems that are NOT school taught. The Block design also requires spatial processing, visual-motor coordination and the ability to apply all skills in a quick, efficient manner. The highest scores reflect both accurate and very quick responses. Picture Concepts score may differ from these other subtest because of the effect of language on the preformance.
Working Memory Index (WMI): Requires working memory processes applied to the manipulation of orally presented verbal sequences. The ability to temporarily retain information in memory, by performing some operation or manipulation with it, and produce a result. Involves attention, concentration, mental control, reasoning. Essential component of other cognitive higher order progresses. Closely related to achievement and learning (People with Learning Disability frequently affected).
Processing Speed (PSI): Requires visual perception and organization, visual scanning, and the efficient production of multiple motor responses. These tasks require executive control of attention and sustained effort for a 2-minute period of time while working with simple visual material as quickly as possible. Performance on Coding is also dependent on paired-associative learning.
WAIS-III by Wechsler, D. (1997),
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