We explain how the most complete intelligence test is when generating an IQ and the most used.
The different versions of the Wechsler Intelligence Scale for Adults have dominated the field of cognitive assessment 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.
The Wechsler Adult Intelligence Scale (WAIS)
David Wechsler (1896-1981) was an American psychologist who trained with Karl Pearson and Charles Spearman, pioneers of psychometry. In 1955 he published the first version of the test that we know as the “Wechsler Adult Intelligence Scale”, commonly called “WAIS” for its initials 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 of what would be Wechsler’s definitive work. Both tests 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, the 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. It replaces the verbal and manipulative quotients with four more specific indices (verbal comprehension, perceptual reasoning, working memory and processing speed). and a General Capacity Index is added that is used in the clinical setting.
Since the first WAIS, these tests have focused on evaluating people over the age of 16. There is also the Wechsler Intelligence Scale for Children (WISC) and the Wechsler Intelligence Scale for Preschool and Primary (WPPSI). Currently the WISC is in its fifth version and the WPPSI in the fourth, and the fifth WAIS is being worked on.
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 like Raven’s, or Information, which evaluates general knowledge.
Each of these tests weights in a larger 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; however, 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 the knowledge acquired, and also of the recovery of long-term memories.
The main tests of the Verbal Comprehension index are the Similarities, the Vocabulary and the Information tests. 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” in the passage 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 relates to fluent reasoning and perception rather than verbal.
The classic tests that make up this index are Design with cubes (create figures seen in images using cubes), Matrices and Incomplete figures. It also includes two new tests: Visual Puzzles and Figurative 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 assesses the ability to apprehend and retain information in the short term, as well as to carry out cognitive operations on it. It is composed of two basic tests: Arithmetic and Digit Hold. It also includes the complementary test Succession of numbers and letters.
4. Processing speed
Processing speed is a measure of individual abilities to process visual information quickly and efficiently. Results on the tests that make up this index also serve as a secondary indicator of motor speed.
The two main tests that weights in this index are Symbol Search and Keys. Cancellation, which is the only new test on the WAIS-IV along with Visual Puzzles and Figure Weight, serves as a supplemental factor.