What is used to calculate a General Ability Index score?

• A. Verbal and perceptual reasoning subtests scores
• B. A composite of all ten subtest scores
• C. Core verbal and perceptual reasoning subtests scores
• D. The General Ability Index

Answer: (C)

The General Ability Index is derived from the core verbal and perceptual reasoning subtests—the ones that form the Verbal Comprehension and Perceptual Reasoning indices. It excludes the Working Memory and Processing Speed subtests, so it reflects reasoning and knowledge rather than speed or memory demands. In practice, you combine the scores from those core verbal and perceptual subtests to obtain the GAI, providing an estimate of general intellectual ability that is less affected by performance factors tied to speed and working memory. For example, subtests like Similarities, Vocabulary, and Information (verbal) and Block Design, Matrix Reasoning, and Visual Puzzles (perceptual) feed into the GAI.