The different versions of the Wechsler Intelligence Scale for Adults have dominated the field of cognitive evaluation in people over 16 years of age since the 1950s and have contributed decisively to the conception of intelligence in the field of 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 in particular on the latest version, the WAIS-IV scale, although we will begin by reviewing the history of this method of assessing cognitive abilities.
David Wechsler (1896-1981) was an American psychologist who trained with Karl Pearson and Charles Spearman, pioneers of psychometrics. In 1955 he published the first version of the test we know as “Wechsler Adult Intelligence Scale”, commonly called “WAIS” by its acronym in the original English.
Previously, in 1939, this author had contributed to the creation of the Wechsler-Bellevue Intelligence Scale, which can be considered a direct precursor to what would be Wechsler’s definitive work. Both tests They conceived intelligence as a set of interrelated elements that could be measured independently.
In 1981, a revised version of the Wechsler Adult Intelligence Scale (WAIS-R) appeared. Later, in 1997, WAIS-III was launched; This new test contained updated scales applicable to many types of population and distinguished between verbal and manipulative IQ, in addition to the total, which was obtained by combining the previous two.
The most recent version of the Wechsler test is the WAIS-IV which was published in 2008. In this, the verbal and manipulative quotients are replaced by four more specific indices (verbal comprehension, perceptual reasoning, working memory and processing speed) and a General Ability Index is added that is used in the field clinical.
Since the first WAIS, these tests have focused on testing people over 16 years of age. There are also the Wechsler Intelligence Scale for Children (WISC) and the Wechsler Preschool and Primary Scale of Intelligence (WPPSI). Currently the WISC is in its fifth version and the WPPSI in its fourth, and work is being done on the fifth WAIS.
Scales and main tests of the WAIS-IV test
Wechsler intelligence tests measure different abilities using specific tests. Some of the most characteristic are Symbol Search, which consists of identifying visual elements as quickly as possible, Matrices, similar to intelligence tests such as Raven’s, or Information, which evaluates general knowledge.
Each of these tests weighs a broader index. In the WAIS-III, the Verbal Comprehension and Working Memory indices were part of the Verbal IQ, while Perceptual Organization and Processing Speed were part of the Manipulative IQ; nevertheless, In the WAIS-IV we only find these indices together with the total IQ which combines them.
1. Verbal comprehension
The Verbal Comprehension index reflects the aptitude of a given individual to understand and use verbal language, in addition to the reasoning abilities associated with this type of material. It is also a good indicator of the quantity and quality of knowledge acquired and also the recovery of long-term memories.
The main tests of the Verbal Comprehension index are the Similarities test, the Vocabulary test and the Information test. 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 “Perceptual Organization” in the transition from the third WAIS to the fourth. This factor measures the ability of the person evaluated to interpret, organize and think correctly using visual information ; Therefore, it is related to fluid reasoning and perception more than verbal.
The classic tests that configure this index are Design with cubes (creating figures seen in images using cubes), Matrices and Incomplete figures. It also includes two new tests: Visual Puzzles and Figured Weight. The first is central to the calculation of the Perceptual Reasoning index, while Figurative Weight is a complementary subtest.
3. Working memory
The Working Memory index evaluates the ability to apprehend and retain short-term information, as well as to carry out cognitive operations on it. It is made up of two basic tests: Arithmetic and Digit Retention. It also includes the complementary test Sequence of numbers and letters.
4. Processing speed
Processing speed is a measure of individual abilities to process visual information quickly and efficiently The results on the tests that make up this index also serve as a secondary indicator of motor speed.
The two main tests that weigh in this index are Symbol Search and Keys. Cancellation, which is the only new test in the WAIS-IV along with Visual Puzzles and Figured Weight, serves as a supplemental factor.
