Trap Perception

[RaizielDragon]

Can someone explain how using Perception to notice traps works? I see in the Perception rules that it says that a player has to state they are looking for traps. Why would they not be, though? Is there some sort of penalty to speed/movement the player should be taking if "looking for traps"?

I had heard from someone else in our group that searching an adjacent square for traps was a full-round action. If this is the case, it seems extremely time-consuming for the party.

Why isn't there just a perception check by everyone when they get near the trap? It says in the trap rules that a player gets a Perception check to notice the trap before setting it off.

[BretI]

I don't see anywhere in the rules that it specifically states you must actively search in order to get a Perception check. I run it as you get a perception check when at the trigger. If you have the Rogue talent Trap Spotter, that would make two rolls -- one when within 10' and another when at the trap.

Actively searching is a move action. You can search for more than one round (which is much slower).

[RainyDayNinja]

Making a Perception check is a move action. If you're on the clock, due to buff spells or a time-sensitive mission, that can add up if you're too cautious.

[Brain in a Jar]

Rogue's can get a talent to attempt to find traps just by being near them.

Trap Spotter (Ex) (PRPG Core Rulebook pg. 69 (Amazon)): Whenever a rogue with this talent comes within 10 feet of a trap, she receives an immediate Perception skill check to notice the trap. This check should be made in secret by the GM.

Otherwise searching for traps is a move action.

"Intentionally searching for stimulus is a move action."

So lets use the following as an example.

The group comes upon a hallway that is 10 feet wide and 40 feet long. At the end of the hallway is a wooden door.

In the hallway is a Pit Trap(Perception DC 20) 20 feet into the hallway and at the end of the hallway, so 40 feet away from the hallway entrance, is a Arrow Trap (Perception DC 20).

The parties Rogue moves to the entrance of the hallway and uses a move action to search it.

You then would use "Distance to the source, object, or creature" modifier to modify the DC to find the traps based on distance.

So if the Rogue is searching at the entrance the DC to find the Pit Trap would be DC 20 for the trap +2 DC for being 20 feet away so DC 22 Perception for the Pit Trap and Arrow Trap would be DC 24 since it is 40 feet away.

At that point the Rogue could either roll or take 10 as a move action to search the hallway or take his time with take 20 spending about 2 minutes to check it.

[BretI]

Brain in a Jar wrote:

Otherwise searching for traps is a move action.

"Intentionally searching for stimulus is a move action."

Yes, but you ignored the first part of that.

CRB, pg. 102 wrote:

Action: Most Perception checks are reactive, made in response to observable stimulus. Intentionally searching for stimulus is a move action.

Traps have a Perception DC. I would argue that this makes them observable stimulus.

As I said above, one free perception check at the trigger. Trap Spotter gives you a second free one. Searching takes a move action and would get you yet another check.

[Saldiven]

WARNING: This is totally a house rule of mine, but it's become quite popular.

With my current Iron Gods campaign, I've started using what I call a "Passive Perception Check." I operate under the assumption that unless the party is being actively distracted by something (combat, conversation, arguing among themselves, etc.) or actively conducting a search, they are paying an average amount of attention to their surroundings. This translates to all of the characters constantly Taking 10 on a Perception Check (except where previously mentioned).

I have cheat cards for each character that includes important stuff like their Perception skill modifier, so when they come near something that is possible to notice without actively searching for it (a secret door in a wall, a covered pit trap, an ambush, etc.), I will use that modifier + 10 to determine whether or not they notice. Of course, if the party has chosen to actively search, they can always roll in the hopes of getting a higher score, and the party often will when they think it is necessary.

I started doing this because I hated tipping the players off that something was up by asking them to roll for Perception, and asking for fake Perception rolls seemed like a waste of time. With this system, if the party doesn't notice something hidden, they have no meta-gamey indication that something was there to notice in the first place.

[Gwen Smith]

I get everyone's perception bonus at the start of the game. I assume everyone in the party is taking 10 on perception as they go along, unless they tell me they are doing something else (concentrating on a spell, watching a prisoner, whatever). If someone's take 10 gets the DC, I let them have it.

Of course, I started out playing in a group where we were forced to say, "I step into this square. I look to my right (roll), I look to my left (roll), I look up (roll), I look down (roll), I look in the three squares in front of me (roll, roll, roll)..." Every single step. We could take an hour of real time to walk across a completely empty 30 foot room.

Yeah, no thanks. Just kill me now--I have actual fun stuff to do.

[RaizielDragon]

That's kind of what I was getting at. I just joined a new group and on the first session, while our group was passing through a large cave complex (with lots of different paths that all cross/converge; basically one big cavern with lots of stalagmites/columns) the DM basically made the statement that he assumed we weren't checking for traps unless we said we were; it was made as a general statement to how he ran things, not as an indication that there might be traps there.

It made me wonder what the penalty or drawback to "checking for traps" might be, as I didn't see any reason to assume we weren't unless there was a drawback to doing so.

So when I looked it up, and saw that it seemed like you have to actually take an action (any kind of action will mean that out-of-combat time will slow to a crawl) to make the perception check, it seemed like you might as well either a)expect your adventures to take a LOT of time or b) just accept that you aren't making perception checks for traps and just plan to survive/deal with them instead.

The idea of making one roll to check an entire area (like a hallway) might help, and a narrow hallway might be a tip off, but doesn't really work in some situations. Like if you are in a big open area where there might be pit traps, how often should you say your character is checking? You would have to specify every time you want to stop and make a new check, hopefully deciding to stop in time to make the check at a point where you are close enough to spot the trap, but not so close that if you fail you will walk over it before you decide to stop again. Alternatively, if the entire area is narrow hallways (like dungeons or sewers), you have the same problem. Do you stop at every intersection or corner to make a new check? How far down the hallways do you go before you make another one? Etc.

I like the idea of the assumed taking a 10 constantly. 4e had passive checks for just this kind of situation, which was essentially a take-10.

Alternatively, I like the idea of just getting a Perception check when nearby, but then that kind of defeats the purpose of the Trap Spotter talent, which is why I didn't think you got such a check. The GM even brought this talent up, because he knew we didn't have it and made a point to say so, implying that we wouldn't be getting a check unless we said we were checking for traps.

[Ascalaphus]

This question has come up several times. The truth is the perception rules aren't perfect or quite like the writers wanted them, but overhauling them is hard because they're used in so many places.

The section on consolidated skills in Unchained (pages 61-62) gives good insight into how perception might work if it had been written today; it distinguishes more clearly between passive perception (noticing someone is sneaking up on you) and active perception (searching for treasure in a pile of junk). Noticing hidden traps is placed in the second category and takes a Move action to search a 10x10 ft area.

I think this is somewhat neater than the CRB rules, which do not actually have a description for the "hands on" searching required for things you can't find just passively because they might be hidden under something else.

It also makes the Trap Spotter talent and Stonecunning traits more useful and clarifies their non-redundancy compared to regular perception.

That said, as a GM you don't want to encourage players to roll for every square: I'd allow players to state they'll Take 10 to search every 10ft for example, and simply have them move at an average speed of 10ft/2 rounds. If something interesting is found I'll pause the game when they get to it.

[RealAlchemy]

Gwen Smith wrote:

I get everyone's perception bonus at the start of the game. I assume everyone in the party is taking 10 on perception as they go along, unless they tell me they are doing something else (concentrating on a spell, watching a prisoner, whatever). If someone's take 10 gets the DC, I let them have it.

Of course, I started out playing in a group where we were forced to say, "I step into this square. I look to my right (roll), I look to my left (roll), I look up (roll), I look down (roll), I look in the three squares in front of me (roll, roll, roll)..." Every single step. We could take an hour of real time to walk across a completely empty 30 foot room.

Yeah, no thanks. Just kill me now--I have actual fun stuff to do.

I liked how the last game I played my investigator was handled. "I have a +24 perception, all three rogue trap abilities, and I roll inspiration on perception for free from the expanded inspiration. Tell me when I see a trap walking down the hall."

[Jiggy]

BretI wrote:

CRB, pg. 102 wrote:

Action: Most Perception checks are reactive, made in response to observable stimulus. Intentionally searching for stimulus is a move action.

Traps have a Perception DC. I would argue that this makes them observable stimulus.

If simply being "observable stimulus" qualifies for a reactive check, then I'm really curious what you'd say it takes to for something to require a move action. There has to be a dividing line somewhere, or else there wouldn't be the two different kinds of checks.

[Matthew Downie]

Non-observable: a trap that you can only find by physically interacting with your environment, maybe? Like a rune hidden under a rug?

[RaizielDragon]

Ascalaphus wrote:

That said, as a GM you don't want to encourage players to roll for every square: I'd allow players to state they'll Take 10 to search every 10ft for example, and simply have them move at an average speed of 10ft/2 rounds. If something interesting is found I'll pause the game when they get to it.

And see, this is the issue. I agree that this is exactly how the rules state it should be done (taking an action to make a check). But now the party is moving at a 5ft land speed. That can cause its own issues when traversing extensive complexes or when under a time crunch for mission reasons.

It also means the party has to move in a controlled fashion or risk not using the 10' squares the scout has already checked.

[Ascalaphus]

RaizielDragon wrote:

Ascalaphus wrote:

That said, as a GM you don't want to encourage players to roll for every square: I'd allow players to state they'll Take 10 to search every 10ft for example, and simply have them move at an average speed of 10ft/2 rounds. If something interesting is found I'll pause the game when they get to it.

And see, this is the issue. I agree that this is exactly how the rules state it should be done (taking an action to make a check). But now the party is moving at a 5ft land speed. That can cause its own issues when traversing extensive complexes or when under a time crunch for mission reasons.

It also means the party has to move in a controlled fashion or risk not using the 10' squares the scout has already checked.

It's an issue, but it's a good issue. If you have all the time in the world, traps aren't usually that scary and therefore uninteresting. But if you're under time pressure (bad guys getting stuff done/away, buffs running out, heck even rations when exploring a really vast cave system) you need to start making choices, and you need an efficient metric what the "cost" is for checking for traps everywhere.

[Brain in a Jar]

RaizielDragon wrote:

Ascalaphus wrote:

That said, as a GM you don't want to encourage players to roll for every square: I'd allow players to state they'll Take 10 to search every 10ft for example, and simply have them move at an average speed of 10ft/2 rounds. If something interesting is found I'll pause the game when they get to it.

And see, this is the issue. I agree that this is exactly how the rules state it should be done (taking an action to make a check). But now the party is moving at a 5ft land speed. That can cause its own issues when traversing extensive complexes or when under a time crunch for mission reasons.

It also means the party has to move in a controlled fashion or risk not using the 10' squares the scout has already checked.

By how the rules are a player searching for traps could move action search for traps and then move 30 feet. Which is a fairly decent speed and allows for decent coverage, since at most a -3 penalty for distance modifiers.

It slows down to a crawl if they make use of taking a 20 to search; since that takes about 2 minutes.

[Jiggy]

Matthew Downie wrote:

Non-observable: a trap that you can only find by physically interacting with your environment, maybe? Like a rune hidden under a rug?

If an intentional Perception check includes moving stuff around, then I have two questions:

1) Why not just say so in the rules?
2) Why doesn't such an action trigger the very trap you're looking for? We know it doesn't because using Perception actively to search for traps is explicitly listed as something you can Take 20 on, and Take 20 isn't allowed if failure would produce harmful effects. So you can spend 20 move actions deliberately searching for a trap without setting it off in the process (this much is explicit in the rules), so if that involves moving rugs out of the way and whatnot, then why isn't the trap triggering?

[CampinCarl9127]

I will never spring a trap on my players without asking them for a perception check or explaining a room/hallway in detail. My players know this so we don't waste an hour every session rolling paranoid perception checks.

[Ascalaphus]

@Jiggy: presumably you start by gently poking the rug with a stick to see if stuff happens. It's all a bit abstract, like traps in general. Trap triggers tend to be stuff like "location", not "pressure plate".

Other example: a diamond is hidden because there's a dead kobold lying on top of it. You can't see that without moving the kobold. That would be an example of what was once "search" as opposed to "spot".

[Brain in a Jar]

CampinCarl9127 wrote:

I will never spring a trap on my players without asking them for a perception check or explaining a room/hallway in detail. My players know this so we don't waste an hour every session rolling paranoid perception checks.

Understandable. It's not fun wasting time.

I'm just not getting why people think it takes up so much time. The average room in dungeons and hallways make it out to be about one Perception check per room.

Now I'm not saying that is the normal space for everything. But look at the size of an average room/hallway on a Pathfinder Adventure. One search covers most if not all of an area.

[Jiggy]

Ascalaphus wrote:

Other example: a diamond is hidden because there's a dead kobold lying on top of it. You can't see that without moving the kobold. That would be an example of what was once "search" as opposed to "spot".

To be clear, I'm totally on board with not being able to see the diamond unless you move the kobold. I just contest the suggestion that doing so is what is meant when the Perception rules state that "Intentionally searching for stimulus is a move action."

Sure, you might come up with certain specific examples where having that rule include moving stuff doesn't come up with any problems, but "you can take 20 to search for traps without setting them off" applies to all traps categorically. You've got to parse the rules in a way that it works consistently, not just be able to come up with certain scenarios where it works.

[Matthew Downie]

If a trap is triggered by stepping on it, it probably isn't triggered by lifting the rug that conceals it. If a trap is triggered by opening a door, it probably isn't triggered by sliding a mirror under the door to check for abnormalities.

I'm not really advocating this interpretation, but it sounds like it could work.

[Ascalaphus]

@Jiggy: we're mostly in agreement then. As I see it, going by current rules you have two options:

- Passive perception
- Active perception: taking time to look and listen closely. This is still hands-off perception, but essentially gives you a second chance to notice stuff you didn't notice earlier (due to a roll not being high enough perhaps).

In both cases you take a +1 DC per 10ft distance; there's no absolute reason stopping you from checking an entire room at once, but to be certain of the best result you'd want to check every 10ft.

There is not actually a rule for hands-on searching.

That accidentally got lost in the folding together of Search, Spot and Listen skills when PF was written up. It was Mark Seifter I think who indicated that he doesn't think it's been done well and that the rules in Unchained are closer to how they'd design it if they got to redo it.

[CampinCarl9127]

Brain in a Jar wrote:

CampinCarl9127 wrote:

I will never spring a trap on my players without asking them for a perception check or explaining a room/hallway in detail. My players know this so we don't waste an hour every session rolling paranoid perception checks.

Understandable. It's not fun wasting time.

I'm just not getting why people think it takes up so much time. The average room in dungeons and hallways make it out to be about one Perception check per room.

Now I'm not saying that is the normal space for everything. But look at the size of an average room/hallway on a Pathfinder Adventure. One search covers most if not all of an area.

Agreed. One perception check per room is pretty efficient.

[RaizielDragon]

The time required also matters if an encounter occurs in a room that has traps. When combat starts, is the Rogue going to waste a move action and his chance to catch someone flat-footed checking for traps? Probably not. He's going to charge across the room and try to bury his dagger in that orc's neck, and probably fall into a pit trap that he wasn't allowed to notice because he didn't take an action to do so.