Reaction Time Test Explained: The Science of Processing Speed [2026]

What is a Reaction Time Test?

A reaction time test measures how quickly you respond to a visual stimulus. When the screen changes from red to green, you click as fast as possible, and your response time is measured in milliseconds.

This test was first systematically studied by Francis Galton in the late 1800s and became foundational to cognitive psychology. Today, it's used across fields including cognitive assessment, sports science, and clinical diagnosis.

Scientific Background

Galton's Pioneering Research

In the late 1800s, Francis Galton proposed that reaction time might be related to intelligence. He tested thousands of subjects and recorded visual reaction times below 190ms in young adults.

In 1890, psychologist James McKeen Cattell proposed reaction time as one of his "mental tests," which Galton endorsed. This laid the foundation for modern cognitive psychology's reaction time research.

Simple vs. Choice Reaction Time

There are two main types of reaction time:

• Simple Reaction Time (SRT): Responding to a single stimulus with a single response. Measures basic processing speed.
• Choice Reaction Time (CRT): Selecting the appropriate response from multiple stimuli. Requires more complex cognitive processing.

This game measures Simple Reaction Time—a pure baseline of processing speed without other cognitive processes like discrimination or selection.

Age and Reaction Speed

Research shows that reaction speed peaks around age 24 and begins a gradual decline thereafter.

Key findings:

• Simple reaction time slows by approximately 2-6ms per decade
• Decline tends to accelerate after age 60
• Choice reaction time declines throughout adulthood, while simple reaction time remains relatively stable until around age 60

Main causes include reduced gray matter volume, decreased white matter integrity, and deterioration of the myelin sheath that transmits neural signals.

Cognitive Abilities Measured

How to Play

1. Start the Game

   Click the "Start" button to begin. You'll complete 5 trials.

2. Wait on Red Screen

   When you see the red screen, wait for it to turn green. Clicking too early counts as "Too Early."

3. Click When Green

   The moment the screen turns green, click as fast as possible. Your reaction time is recorded in milliseconds.

4. View Results

   After 5 trials, you'll see your average reaction time and best time.

Score Guide

Note: Reaction time is affected by many factors including device, fatigue, time of day, and physical condition. Testing multiple times to understand your typical range is recommended.

Training Benefits

Regular reaction time testing may provide these benefits:

• Maintaining Processing Speed: May help slow age-related decline in processing speed
• Improved Attention: Training instant responses to stimuli may enhance everyday attention
• Self-Monitoring: Objectively track changes in fatigue and physical condition through reaction time

Note: Results vary between individuals. Not everyone will experience the same effects.

Tips and Strategies

1. Relax and Focus - Being too tense can be counterproductive. Take a deep breath, relax, and concentrate on the screen change.

2. Look at the Center - Fixing your gaze on the screen center allows fastest detection of color change.

3. Keep Your Finger Ready - Rest your finger lightly on the click button with slight pressure, ready to respond.

4. Don't Predict Patterns - Wait time is randomized (2-5 seconds). Trying to predict patterns leads to early clicks.

5. Choose Optimal Time - Reaction speed varies throughout the day. Play when you're most alert for best results.

6. Avoid When Tired - Sleep deprivation and fatigue significantly impact reaction speed. Test when you're well-rested.

Combining with Dual N-Back

Reaction time testing and Dual N-Back both train cognitive function but target different aspects.

Combining both allows comprehensive cognitive training targeting both processing speed and working memory.

Related Articles:

• How to Start Dual N-Back
• What is Working Memory?
• The Science of Brain Training

FAQ

Conclusion

Reaction time testing has a rich history dating back to the 1800s. Beginning with Francis Galton's pioneering research, it remains widely used today for measuring processing speed and monitoring cognitive health.

While reaction speed peaks around age 24 and gradually declines, training can help maintain and improve it. It's also useful as a tool for objectively tracking your physical condition.

Check your processing speed with this quick and easy reaction time test.