Certified Rehabilitation Counselor Practice

Which of the following is NOT a subtest in the Processing Speed Index?

1. Digit Span

2. Coding

3. Symbol Search

4. Cancellation

The correct answer is: Digit Span

The Processing Speed Index (PSI) is a measure used in psychological assessments, such as the Wechsler scales, to evaluate a person's ability to quickly and accurately process information. It specifically assesses tasks that involve speed and efficiency in performing cognitive tasks. In this context, Digit Span is primarily a measure of Working Memory, not Processing Speed. It involves repeating sequences of numbers in the same order (Forward) or in reverse order (Backward), which requires active manipulation and recall rather than quick processing of visual or motor information. Therefore, it is not included in the PSI. The other subtests listed—Coding, Symbol Search, and Cancellation—all require quick visual scanning and information processing, factors that are central to evaluating processing speed. They measure a person's ability to perform tasks efficiently and accurately under time constraints, which is the purpose of the Processing Speed Index. Hence, Digit Span stands apart as it does not primarily focus on processing speed but rather on memory capabilities.