Man vs App on Jeopardy tonight.

[Alex]

On the trigger. When the production assistant activates the buzzers after Trebek is done reading the question this turns on a light that the human players see, for Watson it sent a digital signal.

As mentioned that gives Watson an advantage since it is capable of essentially instanteous reflexes and can't (as human players risk when trying to time the activation) buzz in early causing a lockout. The other advantage is that by getting a text file Watson was probably often well on its way to an answer before the human players had even had a chance to begin comprehending what it was asking.

Like I said, it is possible that the humans knew more answers than Watson, but that is almost irrelevant if on any question that Watson also knows he is almost guaranteed winning at the buzzer.