Processing Speed: The Overlooked Cognitive Skill
Last updated: June 1, 2025
Processing Speed: The Overlooked Cognitive SkillLast updated: June 1, 2025
What is processing speed?
Processing speed is how quickly the brain can process simple or routine information accurately. It is one of the four major indices of the Wechsler Adult Intelligence Scale (WAIS-IV) alongside verbal comprehension, perceptual reasoning, and working memory. Processing speed is not about intelligence in the complex sense — it measures how fast you can perform basic cognitive operations: scanning, matching, coding. But it underlies almost everything else.
How processing speed is measured
On the WAIS-IV, processing speed is measured through:
| Subtest | Task | What It Measures |
|---|---|---|
| Coding | Copy symbols paired with numbers | Symbol-number association speed |
| Symbol Search | Find target symbols in an array | Visual scanning speed |
| Cancellation | Mark target objects in rows | Visual attention speed |
These tasks are simple by design — the point is to measure speed, not difficulty.
Why does processing speed matter?
Processing speed acts as a bottleneck for more complex thinking. Faster processing means you can:
- Complete tasks before information fades from working memory
- Read faster with better comprehension
- Respond more quickly in conversations without losing the thread
- Spot errors and contradictions more efficiently
Research shows processing speed accounts for a significant portion of age-related cognitive decline, and improvements in processing speed through training partially explain other cognitive gains.
How does processing speed relate to IQ?
Processing speed correlates moderately with general intelligence (g), but the relationship is complex. People with very high IQ do not always have the fastest processing speed — some have very slow careful processing styles combined with high accuracy. However, at the population level, faster processing speed is associated with higher scores on cognitive tests across the board.
How does processing speed change with age?
| Age Range | Processing Speed | Notes |
|---|---|---|
| Childhood | Rapidly increasing | Peaks around late teens |
| 20–30 | Peak | Fastest simple reaction times |
| 30–50 | Gradual decline | May be compensated by experience |
| 50–70 | Noticeable decline | Significant individual variation |
| 70+ | Substantial decline | Healthy aging strategies important |
Processing speed is the cognitive ability that shows the earliest and most consistent age-related decline.
Can processing speed be improved?
Modestly, through specific training, but the gains are limited. Action video games have the strongest evidence for improving visual processing speed. Physical exercise, particularly aerobic exercise, also shows consistent associations with faster processing speed. However, broad processing speed gains comparable to working memory training are not well established.
Low processing speed and learning
Children and adults with low processing speed may have an "intelligence-processing speed mismatch" — strong reasoning but slow execution — which can be misread as low ability. This is particularly common in ADHD and specific learning disabilities. Accommodations like extended time on tests are specifically designed to address this.
Frequently Asked Questions
Is processing speed the same as reaction time?
Related but distinct. Simple reaction time is the speed to respond to a single stimulus. Processing speed, as measured by the WAIS, involves accuracy as well as speed on symbolic tasks.
Does low processing speed mean low IQ?
No. The WAIS specifically reports processing speed as a separate index because it can differ significantly from other cognitive scores. Many highly intelligent people have lower processing speed scores.
Can you improve processing speed with practice?
Some improvement is possible, especially with action game training. But large, broad gains are not reliably produced by available training methods. The most impactful factors are sleep, physical health, and managing anxiety.
Explore More Cognitive Tests
Take our free IQ-style test to explore your cognitive profile across multiple domains, or the working memory test to assess another key cognitive index. For entertainment purposes only.