Your senses allow you to notice fine details and alert you to danger. Perception covers all five senses, including sight, hearing, touch, taste, and smell.
Perception has a number of uses, the most common of which is an opposed check versus an opponent's Stealth check to notice the opponent and avoid being surprised. If you are successful, you notice the opponent and can react accordingly. If you fail, your opponent can take a variety of actions, including sneaking past you and attacking you.
Perception is also used to notice fine details in the environment. The DC to notice such details varies depending upon distance, the environment, and how noticeable the detail is. The following table gives a number of guidelines.
1 Favorable and unfavorable conditions depend upon the sense being used to make the check. For example, bright light might increase the DC of checks involving sight, while torchlight or moonlight might give a penalty. Background noise might reduce a DC involving hearing, while competing odors might penalize any DC involving scent.
2 As for unfavorable conditions, but more extreme. For example, candlelight for DCs involving sight, a roaring dragon for DCs involving hearing, and an overpowering stench covering the area for DCs involving scent.
Most Perception checks are reactive, made in response to observable stimulus. Intentionally searching for stimulus is a move action.
Retry? Yes. You can try to sense something you missed the first time, so long as the stimulus is still present.
About This Section Optionally, a character who reaches 5, 10, 15, or 20 ranks in a skill unlocks various bonuses and abilities unique to that skill. The unchained rogue uses these rules extensively, but others can gain access to them with a new feat.
In this system, characters unlock additional abilities when they attain 5, 10, 15, and 20 ranks in a skill. The skill unlocks system interfaces with the unchained rogue to make the rogue the true master of skills.
Skill unlocks give characters new abilities and ways to use their skills upon reaching 5, 10, 15, and 20 ranks in a skill. Any character with the Signature Skill feat can earn skill unlocks for a single skill, and they are a prime feature of the revised version of the rogue who uses her rogue's edge ability to gain skill unlocks for several of her most iconic skills. Alternatively, you might make skill unlocks a universal part of the game, but you should be aware they add significant power and flexibility to skills, so giving them for free to all classes would grant power boosts to other highly skilled classes such as the investigator and bard, particularly in comparison to the rogue. Another alternative is to eliminate access to the Signature Skill feat, limiting skill unlocks to rogues and rogues alone.
With sufficient ranks in Perception, you earn the following.
5 Ranks: You remain alert to sounds even in your sleep, and the normal DC increase to Perception checks when you are sleeping is halved. The distance modifier on the DC of Perception checks you attempt is reduced to +1 per 20 feet.
10 Ranks: The distance modifier on the DC of Perception checks you attempt is reduced to +1 per 30 feet. In addition, you gain a +5 bonus on Perception checks to notice or locate an invisible creature or object.
15 Ranks: You remain alert to sounds even in your sleep, and the normal DC increase to Perception checks when you are sleeping doesn't apply to you. The distance modifier on the DC of your Perception checks is reduced to +1 per 40 feet.