Different versions of the Wechsler Scale of Adult Intelligence have dominated the field of cognitive assessment in people over the age of 16 since the 1950s and have contributed decisively to the design of intelligence in the field. in psychology and in society in general.
In this article we will analyze the main scales and tests of the WAIS intelligence test. We will focus particularly on the latest version, the WAIS-IV scale, but we will begin by reviewing the history of this method of assessing cognitive abilities.
The Wechsler Adult Intelligence Scale (WAIS)
David Wechsler (1896-1981) was an American psychologist trained with Karl Pearson and Charles Spearman, pioneers of psychometrics. In 1955 he published the first version of the test known to us as “Wechsler Adult Intelligence Scale”, commonly known as “WAIS” for its acronym in the English original.
Previously, in 1939, this author had contributed to the creation of the Wechsler-Bellevue Intelligence Scale, which can be considered a direct precursor of what would be Wechsler’s definitive work. The two tests they conceived intelligence as a set of interdependent elements which could be measured independently.
A revised version of the Wechsler Scale of Adult Intelligence (WAIS-R) appeared in 1981. Subsequently, in 1997, the WAIS-III was launched; this new test contained updated scales applicable to many types of population and distinguished verbal and manipulative IQ, in addition to the total, obtained by combining the previous two.
The latest version of the Wechsler test is the WAIS-IV, Which was published in 2008. This replaces the verbal and manipulative quotients with four more specific cues (verbal comprehension, perceptual reasoning, working memory and processing speed) and adds a general ability index which is used in the clinical setting.
Since the first WAIS, these tests have focused on assessing people over 16 years of age. they also exist Wechsler Intelligence Scale for Children (WISC) and the Wechsler Preschool and Elementary Intelligence Scale (WPPSI). WISC is currently in its fifth version and WPPSI in its fourth, and work is underway on the fifth WAIS.
Scales and main tests of the WAIS-IV test
Wechsler’s intelligence tests measure different abilities using specific tests. Some of the most characteristic are symbol search, which involves identifying visual elements as quickly as possible, matrices, similar to intelligence tests such as Raven’s, or Information, which assesses general knowledge.
Each of these tests weighs on a larger index. In WAIS-III, verbal comprehension and working memory cues were part of verbal CI, while perceptual organization and processing speed were part of manipulative CI; However, in WAIS-IV we only find these indices with the total CI, Which combines them.
1. Verbal comprehension
The Verbal Comprehension Index reflects a person’s ability to understand and use verbal language, in addition to the reasoning skills associated with this type of material. It is also a good indicator of the quantity and quality of knowledge acquired, And also long term memory recovery.
The main tests of the Verbal Comprehension Index are those of similarities, vocabulary and information. On the other hand, the comprehension test can be used as a complementary factor in the calculation of this index.
2. Perceptual reasoning
The terminology “Perceptual Reasoning” replaced that of “Perceptual organization” when switching from the third WAIS to the chamber. This factor measures the ability of the person being assessed to interpret, organize and think correctly using visual information; therefore, it is fluent reasoning and perception rather than verbal.
The classic tests that make up this index are Cube Design (creation of figures seen in images using buckets), Arrays and Incomplete Figures. It also includes two new tests: visual puzzles and figurative weight. The first is at the heart of the calculation of the perceptual reasoning index, while the figurative weight is a complementary subtest.
3. Working memory
The working memory index evaluates the ability to grasp and retain information in the short term, As well as to perform cognitive operations there. It consists of two basic tests: arithmetic and keeping numbers. It also includes the additional test Succession of numbers and letters.
4. Processing speed
Processing speed is a measure of individual skills for process visual information quickly and efficiently. The test results that make up this index also serve as a secondary indicator of engine speed.
The two main tests that weigh in this index are finding symbols and keys. The cancellation, which is the only new test of the WAIS-IV with the visual puzzles and figurative weight, serves as an additional factor.