When you run a simple reaction test on Reaction Test — Level 1, it may feel like a basic click game. In reality, your score condenses a long chain of events into a single number in milliseconds.
1. The full reaction time chain
A typical “wait for green, then click” task combines several stages of processing:
- Detection – light hits the retina and triggers photoreceptors.
- Transmission – signals travel through the optic nerve and thalamus.
- Perception – visual cortex turns raw input into “the screen changed”.
- Decision – premotor areas decide “now it is time to click”.
- Motor command – motor cortex activates finger muscles.
- Movement – the command runs down the spinal cord to the hand.
All of this unfolds in a fraction of a second. The number you see after a trial is the sum of these steps plus device and browser delays.
2. What counts as a “good” simple reaction time?
In healthy adults using a normal keyboard or mouse on a laptop or desktop:
- Most people fall roughly in the 200–250 ms range.
- Well-rested, focused users sometimes dip below 180 ms.
- Fatigue, distractions or poor sleep can push results above 300 ms.
The important part is the pattern, not a single heroic attempt. Your nervous system is noisy: any one trial can be unusually fast or slow.
3. Why nerves are fast but the brain is slower
Fast sensory and motor fibres conduct on the order of tens of metres per second. This means that pure signal travel from eye to brain or brain to hand is quick – often just a few milliseconds.
The bigger bottleneck is in cortical processing and decision initiation. The brain must recognise that the stimulus is real, not noise, and trigger an action at the right moment. This processing cost dominates your reaction time.
4. Hardware and software latency
Your scores also reflect properties of your device, not just your biology:
- Display latency – how long it takes pixels to change colour and the frame to be shown.
- Input lag – how often the mouse or touchpad reports its state (polling rate).
- Browser and OS – how quickly the click event is delivered to the test code.
This is why it is best to compare yourself to yourself using the same device and browser, rather than to other people using unknown setups.
5. Simple vs choice reaction time
Our Reaction Test — Level 2 adds a small decision: you must react only to some targets. This is closer to real situations, where you rarely respond to every stimulus.
Compared with simple reaction time, choice reaction time usually:
- Is slower, because you must choose between options.
- Generates more very slow lapses when attention slips.
- Engages more frontal “executive” regions involved in control.
6. Day-to-day factors that move your score
Several common factors shift reaction times without changing your basic ability:
- Sleep – short or fragmented sleep almost always slows responses.
- Stress and arousal – a mild increase can sharpen focus, but chronic stress tends to hurt performance.
- Caffeine – may speed responses slightly, but also increase jitters and false starts.
- Practice – repeated testing improves timing and reduces hesitation.
7. How to use reaction tests intelligently
Rather than chasing the single best number you can produce, treat reaction time as a small monitoring tool:
- Use the same test and device (Level 1 or Level 2).
- Log a few attempts on good days and bad days.
- Watch how averages and outliers change over weeks, not minutes.
If you notice large, persistent changes in your response speed, mood or functioning, it can be useful to discuss them with a qualified professional. Online tests are not diagnostic, but they can help you notice trends.
These notes are for general education only and do not diagnose any condition or replace medical or psychological care. Use your results as one data point, not a verdict on your abilities.