The next development in the history of intelligence testing was the creation of a new measurement instrument by American psychologist David Wechsler (January 12, 1896 – May 2, 1981).It is really more complicated test and we think that it isnot suitable for a distance value. It was formed with a lot of sets and subsets.In short:

The Wechsler Intelligence Scales

WAIS test

Fourteen subtests -- seven verbal (Information, Comprehension, Arithmetic, Similarities, Vocabulary, Digit Span, and Letter-Number Sequencing), and seven performance (Digit Symbol-Coding, Picture Completion, Block Design, MatrixReasoning, Picture Arrangement, Symbol Search, and Object Assembly).

In the next two chapters, we are going to define the two main sets.