An overlay graphic appears (see image, right) and the player's head automatically turns towards the Creature. The closer the Creature is, the more opaque the graphic will appear. If the graphic turns red, this indicates that you are visible to the Creature, even though he may still not have actually seen you (he might not be looking in your direction). It is possible to gather, synthesize and use this multiple times, increasing player's Perception to High. This does not, however, give any additional benefits.
Mental stimulants are the temporary version of the Brain Emphasis Drug.