One of two boxes will light up. Press the matching side — ← Left key or → Right key (or tap the box). 10-trial average. Choice RT is ~60ms slower than simple RT.
Hick's Law (1952) states that reaction time increases logarithmically with the number of choices. Two choices adds ~50-70ms over simple reaction time. This "decision time" reflects how quickly the brain can discriminate between stimuli and select the correct response.
Compare with your Simple Reaction Time. The difference reveals your personal decision-making overhead.
Choice Reaction Time (CRT) extends simple reaction time by requiring a decision between stimuli. The task — two lights, press the matching side — introduces a stimulus-identification step that adds approximately 50–80ms to your response time compared to simple RT. This difference, the decision time component, is predicted by Hick's Law (1952): reaction time increases logarithmically with the number of choices. Two alternatives add roughly one "bit" of information, and each additional bit costs approximately 150ms.
Hick's Law has profound implications for product design, aviation, and combat — situations where the number of available choices determines response speed under pressure. Fighter pilots are trained to minimize decisions under combat conditions precisely because each additional option adds cognitive processing time. UI designers use Hick's Law to limit menu options and reduce user response time. Understanding your personal Hick's Law coefficient — how much each additional choice costs you — is a meaningful index of decision-making efficiency.
Compare your CRT score with your Simple RT score to isolate your personal decision-time overhead. If the difference exceeds 100ms, stimulus discrimination (identifying left vs right quickly) may be slower than your detection speed — suggesting that spatial processing or response selection is your bottleneck rather than neural conduction speed. If the difference is under 50ms, you are especially efficient at integrating the detection and decision steps.
Average CRT on our platform is approximately 360–400ms. The global average for simple RT is ~284ms, giving a typical decision overhead of 80–120ms. Athletes in reactive sports (tennis, cricket, boxing) show smaller-than-average decision overhead, reflecting practice at rapid stimulus-response translation.