Sense Rolls

Vision, Hearing, Smell/Taste, and more exotic senses like Scanning, Vibration, etc.
Roll against your Perception Score modified by any applicable Acute Senses advantage.

These Sense rolls or Perception rolls are optionally rolled by the GM, where they then tell the characters if they noticed anything.

Comprehension Rolls:
Sometimes you notice something, but that is not enough (the "owl hoot" is a hidden warrior's call, the flower scent belongs to a man-eating plant!)
This roll is against IQ or an appropriate skill if an expert must notice it.

Vision
Modifiers:

• -1 to -9 for varying levels of partial darkness.
  • Vision rolls are impossible in total darkness without special advantages or tech.
• Things in plain sight are not usually worth rolling for, but if you must, they are at +10.

Hidden things are a Quick Contest against (Camouflage, Holdout, etc.) and may allow or require Observation or Search (or similar) instead of a Perception roll.
The horizon is about 3 miles out for a 5-6 foot tall person.

Hearing
A separate IQ roll is sometimes made to make out speech, especially in a foreign language.

Modifiers:
See Hearing Distance Table (Below)

• +1 for every step you are closer
• -1 for every step you are more distant
• (eg. A normal conversation from 8 yards away adds -3 to your roll)

When attempting to hear someone moving silently use a Quick Contest against their Stealth skill.

• If you are actively listening, the GM may allow Observation instead of Perception.

Hearing Distance Table

Taste/Smell
Modifiers:

• The GM may modify if strong or weak or disguised.