5 ms·

Watson received an electronic signal that the buzzers were active. The human contestants have to time it via Trebek's voice or the light.

• endtime 16y ago
  An electronic signal and a photonic signal ("the light") both travel at the same speed.
  • orborde 16y ago
    An incandescent light might take a nontrivial amount of time (tenth of a second?) to heat up and light after power is applied.
  • locopati 16y ago
    But a computer's detection and response to a signal is probably faster than a human's reaction time.