Processing Speed

Processing speed is the rate at which a person carries out mental operations needed to complete a task with reasonable accuracy. In cognitive testing, it often refers to handling relatively simple information quickly, such as identifying a target or matching a number to a symbol .¹

Processing speed is estimated from performance on timed tasks rather than measured as a single speed inside the brain. Different tasks place different demands on perception, attention, selecting a response, and producing that response. A test requiring written symbols, for example, includes a motor component as well as the mental work of choosing the correct symbol .^1,2

This makes the distinction between processing speed and executive control important. Even apparently simple speed tests may require keeping a rule in mind, filtering irrelevant information, or making decisions. More complicated tasks can place greater demands on these abilities. A processing-speed score therefore describes performance under particular task conditions; its meaning depends partly on what the task requires. Researchers must account for those demands when comparing people or interpreting changes across age groups .²