Click anywhere in this zone to begin reaction test sequence.
Neuro-Optical Pathway: Optical photons hit retinal cones -> signal propagates through the optic nerve to primary visual cortex (V1) -> motor cortex initiates finger flexion (200–250 ms average).
1. Rules: Click the right stage to begin. Wait while it is RED. Click as fast as possible when it turns GREEN!
2. False Starts: Clicking early incurs a false-start penalty.