During the Verbal Comprehension Index (VCI), the child answers spoken or verbal questions. He must understand the question, and apply existing knowledge and reasoning to answer the question. The test measures understanding of verbal communication, processing of information and application of existing knowledge.
The perceptual reasoning index (PRI) does not test verbal skills, but tests visual spatial and motor skills. This part of the exam uses blocks, models and puzzles to test problem solving. The child must visualize the problem, and use the available items to solve it.
The working memory index (WMI) tests short term memory, and the ability to retain and manipulate information. The test measures the ability to concentrate and use information to solve problems. It measures the ability to achieve, mental flexibility, planning and prioritizing information.
The processing speed index (PSI) tests mental reaction time or problem solving speed. It measures the child's ability to scan data, process it and form a solution. Having a good working memory enhances processing speed. This part of the program uses scenarios similar to the other three sections, only now the child is timed.