Which WAIS component is used to assess processing efficiency of mental operations?

• A. Verbal Comprehension Index
• B. Perceptual Reasoning Index
• C. Processing Speed Index
• D. Working Memory Index

Answer: (C)

Processing speed is about how quickly and efficiently a person can carry out simple mental tasks under time pressure. The Processing Speed Index of the WAIS specifically measures this ability by using timed tasks that require fast, accurate responses, such as symbol search and coding. These tasks assess how efficiently someone can transform information into results when speed matters, not just whether they know the information.

This focus on speeded mental operations distinguishes it from the other WAIS indices. Verbal Comprehension looks at language-based understanding and reasoning, not speed. Perceptual Reasoning taps nonverbal problem solving and spatial skills, again independent of how fast you work. Working Memory measures the capacity to hold and manipulate information in mind, which is more about staying on task and maintaining info than speed under time pressure.