Alertness (GURPS) is one of Fallout GURPS advantages. See: Fallout GURPS.
A general bonus you get on any sense roll (p. 24), or when the GM rolls against your IQ to see if you notice something. This advantage can be combined with any or all of the acute senses. Cost: 5 points for each +1 bonus to your roll.”— Steve Jackson Games GURPS sources