Speed Test — Decision
Choice Reaction Time Test
A colored circle appears — click the matching colored button as fast as you can. More choices means slower responses. This is Hick's Law in action. 20 trials, score is your average correct RT.
Choice Reaction Time
Select difficulty, then click Start. Match the center circle color to the correct button.
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Hick's Law: RT grows with choices
In 1952, British psychologist William Edmund Hick published one of the most influential papers in cognitive psychology: a systematic demonstration that reaction time increases as a logarithmic function of the number of stimulus-response alternatives. The relationship is expressed as: RT = a + b × log₂(N + 1), where N is the number of choices and b is approximately 150ms per bit of information.
The logarithmic relationship means that going from 1 to 2 choices adds the most time (~150ms), while going from 7 to 8 choices adds far less (~25ms). The brain is essentially performing a binary search through available options, eliminating half the possibilities with each discrimination step — an efficient but time-consuming process.
Predicted RT by number of choices (Hick's Law)
Simple vs choice reaction time
Simple RT measures the interval from a single expected stimulus to a single pre-planned response — no decision required. The standard reaction time test measures this. Choice RT adds a discrimination phase: the brain must identify which stimulus appeared and select the corresponding response. This additional step — performed by the prefrontal cortex and basal ganglia — adds 80–200ms depending on complexity.
| Measure | Simple RT | 2-choice RT | 4-choice RT | 8-choice RT |
|---|---|---|---|---|
| Global avg (ms) | 284 | 340 | 380 | 455 |
| Top 10% (ms) | 210 | 255 | 295 | 360 |
| Brain regions | Motor cortex only | +PFC discrimination | +Basal ganglia | +Working memory |
| Cognitive demand | Very low | Low | Moderate | High |
Score distribution — 1.6M scores
| Percentile | 4-choice RT | Classification |
|---|---|---|
| Top 1% | <225ms | Exceptional |
| Top 10% | 225–295ms | Elite |
| Top 25% | 295–345ms | Above average |
| 50th (median) | 345–410ms | Average |
| Bottom 25% | >410ms | Below average |
Decision speed in real life
Hick's Law is not merely a laboratory curiosity — it governs real-world performance in ways that affect safety and competitive outcomes. When a driver sees a hazard, the brain must discriminate the type of hazard (pedestrian? pothole? car braking?) and select among responses (brake, swerve left, swerve right, honk). More complex hazard scenarios produce measurably longer response times.
Sports scientists use Hick's Law to explain why elite athletes practice responses until they become automatic — effectively reducing the number of decision alternatives by ingraining the most common response, lowering the information load and shaving critical milliseconds. Quarterbacks, tennis returners, and combat sports athletes all demonstrate this through years of deliberate practice.
Military research has applied Hick's Law to attention and focus training for high-stakes decision-making. Studies of air traffic controllers, fighter pilots, and emergency dispatchers consistently show that workload management — reducing the number of active choices at any given moment — is more effective than trying to speed up the underlying reaction time.
How to improve choice RT
Automate common responses
Practice until frequent responses become reflexive — this effectively reduces choice count, bypassing the logarithmic cost of deliberation. Repetition moves responses from working memory into procedural memory.
Action games
Research by Daphne Bavelier (2012) showed action video game players have faster choice RT and better probability learning. The constant multi-choice demands of action games directly train the discrimination circuitry this test measures.
Varied practice
Alternate between 2-choice, 4-choice, and 8-choice modes to train flexibility. Challenging your brain with more choices during practice makes the lower-choice conditions feel faster by comparison — a well-replicated contextual interference effect.
Cross-train with simple RT
Improving your baseline simple reaction time lowers the floor of every choice RT trial. The decision-overhead component remains roughly constant, so faster motor execution directly translates to better choice RT scores.
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