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Science
What factors affect reaction time?
Reaction time is influenced by a wide range of biological, psychological, and environmental factors. Here are the most significant ones, with approximate effect sizes:
| Factor | Effect on RT | Direction |
|---|---|---|
| Age (peak ~20–25) | 3–5ms per decade | Slows with age |
| Sleep deprivation (1 night) | ~50ms | Slower |
| Caffeine (100–200mg) | ~10–15ms | Faster |
| Alcohol (0.08% BAC) | ~30ms | Slower |
| Warm-up / practice | ~15–20ms | Faster |
| Temperature (cold hands) | ~5–15ms | Slower |
| Stress / anxiety | ~10–20ms (varies) | Faster at low; slower at high |
| Fatigue (end of long task) | ~20–40ms | Slower |
| Action video game training | ~15–20ms | Faster |
| Stimulus expectancy | ~20–40ms | Faster when expected |
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Quick Answer
Age, sleep quality, caffeine, alcohol, stress, temperature, practice, and stimulus type all affect RT. Sleep deprivation alone adds ~50ms. Alcohol at 0.08% BAC adds ~30ms.
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