Nerves and reflexes

The rule falls as a real one does: it speeds up by 9.8 metres per second every second, so a fall of d metres takes √(2 × d ÷ 9.8) seconds. The table gives these times to two decimal places.

Your catch is timed from the moment the drawing shows the rule starting to fall to your tap or key press. The screen and the tap add a little time of their own, so your times are not directly comparable with a real ruler catch.

The prepared results (20, 18, 19, 16, 15 cm) are five catches by one pupil with a real metre rule.

The glow along a neurone is a convention that shows where the impulse is: a real impulse gives out no light. The route of a catch, the reflex and the synapse are slowed down, and their timings are only illustrative.

A reaction time is not a score: it changes with tiredness, attention and practice, so there is no point comparing yours with anyone else’s.

With reduced motion each process is shown at its start and its end. Your own catches are still drawn falling, because the fall is what you react to.