D&D 5E passive perception vs active perception

[monkeydm]

HI,

they way i understand it now, is that with passive perception the character isnt really looking for "something" but might spot it anyway..as opposed to active perception where you are actively looking for "it". Couple of question:

1. does passive perception uses the Wisdom ability?
2. does active perception uses the Intelligence ability?

Say you are on a road and hear a group of Orcs marching on the same road towards you. You jump behind a tree and try to hide. Say the Orcs arent looking for you. The DM lets you make a stealth check and compares this against the passive perception (which is DC10+wisdom ability) of the Orcs. Is there a difference between 1 Orc and 5? Does the player for instance has to make 5 checks in that last case? Of is it still one roll but with a modifier of some sort?

And how would the above scenario play out if the Orcs were active looking for elves.

Thanks in advance

 

[delericho]

1. does passive perception uses the Wisdom ability?
2. does active perception uses the Intelligence ability?

Passive Perception is just 10 + your Wis (Perception) score. Likewise 'active' Perception is d20 + your Wis (Perception) score... unless your DM calls for a different roll.

The purpose of PP is just to speed up the game - instead of constantly rolling Stealth vs Perception, one of those rolls is averaged down. (Obviously, PP is used in other cases. The same logic applies.)

Say you are on a road and hear a group of Orcs marching on the same road towards you. You jump behind a tree and try to hide. Say the Orcs arent looking for you. The DM lets you make a stealth check and compares this against the passive perception (which is DC10+wisdom ability) of the Orcs. Is there a difference between 1 Orc and 5? Does the player for instance has to make 5 checks in that last case? Of is it still one roll but with a modifier of some sort?

I would just use one roll against the highest PP in the group. Since the orcs probably all have the same stats, that's an easy check.

But the Stealth rules are one of the more... controversial elements of 5e.

And how would the above scenario play out if the Orcs were active looking for elves.

Oh, lots of options. I'd almost certainly just use exactly the same resolution, purely for convenience. I might make one roll for the orcs (using the highest available modifier).

Or, if I really wanted to do it 'right', I'd roll for each orc individually. Those that pass the check get to act in the first round; those that fail are surprised.

But note: if everyone in a group rolls individually, then there's an individual consequence. The "I immediately warn the others" trick doesn't work - by the time the roll has been made, surprise applies (or doesn't).

(The reason for this is that if everyone in the group rolls Perception then it's almost certain that someone will succeed. So if you're going to let the one success mean success for the group, you might as well not roll - someone almost certainly will succeed. And the reverse logic applies with Stealth - if everyone is made to roll, someone is all-but-guaranteed to fail.)

 

[neogod22]

So the way it works is, if the check is lower than a player's PP, he notices it automatically. If it's higher, then you can have them roll. As a DM, you can choose to ignore that rule and have them roll anyway (or just have them roll just to roll dice and give it to them anyway). Perception helps you spit things, whereas Investigation helps you to figure things out. So Perception to find the secret door, but it takes Investigation to figure out how to open it.

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[5ekyu]

Iirc the hiders roll stealth against the passive perception of the approaching individuals.

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[Li Shenron]

they way i understand it now, is that with passive perception the character isnt really looking for "something" but might spot it anyway..as opposed to active perception where you are actively looking for "it".

It's more variable than that... "Passive" rolls are more like a metagaming construct to avoid certain players asking a DM to let them roll for trapfinding every couple of meters and thus slowing the game down. They are sometimes quoted as having also the purpose of letting a DM secretly determine if a PC notices something, although this is not really more useful than the DM rolling perception secretly in the PC's place.

Unfortunately, trying too much to link this metagaming-motivated rule to a narrative always caused unwanted consequences since Take10 in 3e. So go there if you want, but be aware that you may open a can of worms. There is already enough ambiguity between Perception and Investigation, that we don't need more discussions between eight different options such as Active Wisdom Perception, Active Intelligence Perception, Active Wisdom Investigation, Active Intelligence Investigation, Passive Wisdom Perception, Passive Intelligence Perception, Passive Wisdom Investigation, Passive Intelligence Investigation. You don't need to use them all, and you don't even need to care too much about which one to use. Remember that at the end it's only a matter of probability of success or failure, and players won't even notice the difference, unless they have very a good perception of probabilities... or is it investigation? :/

Just in case you wish to know, I usually do it as a mix bag, without the pretense of being consistent:

- roll Wisdom Perception for noticing (when not actively searching) noises, visual details, smells, environment anomalies, as well as hidden things, but also when actively listening to a door or visually focusing on something; the key idea is to "see if there is anything to see here" without knowing what you're looking for

- roll Intelligence Investigation when you know what you're looking for, which pretty much implies actively

I don't normally use passive checks at all, because even with repeated/routine trapfinding I prefer to let the PC roll, and then just apply the result to a large window of time instead of a single instant and place (so I might let you roll one Investigation check for a whole hour in the caves, or for a whole locale).

A final suggestion: if you don't want to trap (!) yourself into the situation where passive checks means autosuccess/autofailure, use them only when there is an contest i.e. opposed checks, and obviously let the other side roll.

Say you are on a road and hear a group of Orcs marching on the same road towards you. You jump behind a tree and try to hide. Say the Orcs arent looking for you. The DM lets you make a stealth check and compares this against the passive perception (which is DC10+wisdom ability) of the Orcs. Is there a difference between 1 Orc and 5? Does the player for instance has to make 5 checks in that last case? Of is it still one roll but with a modifier of some sort?

And how would the above scenario play out if the Orcs were active looking for elves.

When you have a group AND the consequences of the check are supposed to affect the whole group, you can always do a (properly named) group check, which means the whole group succeeds if half of its members succeed.

OTOH, if everyone in the group has the same modifier to the roll, it might be just as good to simply roll once for the whole group, especially if the group is large.

The bottom line is that the actual statistical distribution can be very different, but since the outcome is merely success/failure, all you may want to care about is the average. But still, why you should even care about a few % difference in an average, when it would only really matter over a large number of occurrences of exactly the same situation?

 

[robus]

Here’s how I handle it.

First off Passive Perception is not a general radar capability that’s able to detect any thing that crosses the threshold. The character still has to declare an action but it’s just “I’m looking for traps.” “I’m looking for elves.”

So in your example your orcs coming down the path are not looking for anything in particular, just the general terrain. Creatures hiding from them thus either get advantage on their stealth checks or the orcs get disadvantage on their passive perception checks (subtract 5).

If the orcs are hunting for the hiding characters then it’s a straight up passive perception vs. stealth. And here’s the thing, something triggering passive perception doesn’t mean the character knows what it is, just that something seems out of place, and needs a closer look (active perception) or proper investigation.

 

[Charlaquin]

HI,

they way i understand it now, is that with passive perception the character isnt really looking for "something" but might spot it anyway..as opposed to active perception where you are actively looking for "it". Couple of question:

Yes, that is correct.

1. does passive perception uses the Wisdom ability?

Yes. Passive Perception is calculated as [10 + Wisdom mod] + Proficiency bonus if the character is proficient in Perception.

2. does active perception uses the Intelligence ability?

Not by default. Perception is a Wisdom-related skill, so it normally uses the Wisdom ability, whether rolled actively or checked passively. There is a variant rule in the player’s handbook called “skills with different abilities” which allows DMs to combine any skill with any ability at their discretion, so an active Intelligence (Perception) roll is possible, but it is not the standard assumption. Also, many DMs use the Investigation skill for active searching, and that skill is tied to Intelligence by default. Personally, this is not how I interpret the guidelines related to Perception vs Investigation in the books, but it is a very common interpretation, so it’s worth mentioning.

Say you are on a road and hear a group of Orcs marching on the same road towards you. You jump behind a tree and try to hide. Say the Orcs arent looking for you. The DM lets you make a stealth check and compares this against the passive perception (which is DC10+wisdom ability) of the Orcs. Is there a difference between 1 Orc and 5? Does the player for instance has to make 5 checks in that last case? Of is it still one roll but with a modifier of some sort?

Assuming the player meets the requirements to Hide (this is pretty much entirely up to DM discretion,) the player should only need to make one check, usually against the highest Passive Wisdom (Perception) among the group they are hiding from. The DM could rule that the player has disadvantage on their check due to the large number of orcs they are trying to hide from, or give the orcs a bonus to their Passive Wisdom (Perception). +2 for a moderate bonus or +5 for a significant bonus. Situational modifiers like that are entirely up to the DM’s discretion.

And how would the above scenario play out if the Orcs were active looking for elves.

The player should still roll against the orcs’ Passive Wisdom (Perception). If they succeed, then they are Hidden. On the orcs’ turn (or whenever the DM decides to resolve the orcs’ Actions if they aren’t in combat), the orcs can actively search for the elf with a group Wisdom (Perception) check, with the DC equal to the result of the elf’s Dexterity (Stealth) check. The player’s handbook says this about group checks:

“To make a group ability check, everyone in the group makes the ability check. If at least half the group succeeds, the whole group succeeds. Otherwise, the group fails.”

Personally, I don’t care for this method of resolving group checks. I prefer to determine whether the check would succeed if any individual in the group succeeds (like if they’re all searching for the same thing) or if they fail if any individual in the group fails (such as when trying to move silently). In the former case, have the member of the group with the highest bonus make the check, in the latter case, have the individual with the lowest modifier make the check. In either case, consider adding a situational bonus for having help from the rest of the group, such as Advantage, +2, or +5.

 

[neogod22]

Here’s how I handle it.

First off Passive Perception is not a general radar capability that’s able to detect any thing that crosses the threshold. The character still has to declare an action but it’s just “I’m looking for traps.” “I’m looking for elves.”

So in your example your orcs coming down the path are not looking for anything in particular, just the general terrain. Creatures hiding from them thus either get advantage on their stealth checks or the orcs get disadvantage on their passive perception checks (subtract 5).

If the orcs are hunting for the hiding characters then it’s a straight up passive perception vs. stealth. And here’s the thing, something triggering passive perception doesn’t mean the character knows what it is, just that something seems out of place, and needs a closer look (active perception) or proper investigation.

I get it, but the problem with this is, this is a story telling game, and it's the DM's job to be descriptive. It's easy for players to miss things because of lack of details, or the adventure is badly written.

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[robus]

I get it, but the problem with this is, this is a story telling game, and it's the DM's job to be descriptive. It's easy for players to miss things because of lack of details, or the adventure is badly written.

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Sure, but I don't think anything I wrote goes against that? Of course the DM should be descriptive about everything in plain sight, but making everything an auto-success doesn't make things very immersive? If the players don't declare a interest in looking out for particularly things then why should they automatically spot something deliberately hidden?

 

[iserith]

HI,

they way i understand it now, is that with passive perception the character isnt really looking for "something" but might spot it anyway..as opposed to active perception where you are actively looking for "it".

You might consider: A task is not a check. A check is a mechanic used to resolve any uncertainty as to the outcome of a task. This uncertainty is determined and established by the DM. Therefore, a check implies that a task has been performed, but according to the rules on "How to Play," the player is required to describe what he or she wants to do before any check is called for. Without an attempt at a task, there can be no check (and in many cases there isn't one because there's no uncertainty as to the result). Keep this in mind.

Now, under the rules for passive checks, "a passive check is a special kind of ability check that doesn't involve any die rolls." So as you can see here, "passive" isn't referring to the task - it's a descriptor for the check, in that you don't roll dice. It doesn't necessarily mean the character is acting in passive manner. In fact, the rules go on to say "Such a check can represent the average result for a task done repeatedly, such as searching for secret doors over and over again..." That's not a character acting passively.

Taken altogether, we see that this mechanic can be used to resolve tasks described by a player that the character is doing repeatedly over time that also have an uncertain outcome (as determined by the DM).

Couple of question:

1. does passive perception uses the Wisdom ability?

Yes, in general, that is the case.

2. does active perception uses the Intelligence ability?

There is no such thing as "active perception." There are ability checks, for one-off tasks, and passive checks as described above.

Say you are on a road and hear a group of Orcs marching on the same road towards you. You jump behind a tree and try to hide. Say the Orcs arent looking for you. The DM lets you make a stealth check and compares this against the passive perception (which is DC10+wisdom ability) of the Orcs. Is there a difference between 1 Orc and 5? Does the player for instance has to make 5 checks in that last case? Of is it still one roll but with a modifier of some sort?

The one Dexterity (Stealth) check result is compared to each orc's passive Perception, provided the orders are keeping watch while traveling. Some of them might be engaged in other tasks that distract from that. In general, however, it's safe to assume they are always keeping watch on an ongoing basis which indicates a passive check is a reasonable mechanic to resolve the uncertainty (though essentially it's just setting a DC for the PC's task of hiding, one that must be exceeded for success).

And how would the above scenario play out if the Orcs were active looking for elves.

It depends on whether they're engaged in this task in an ongoing basis while traveling. If they aren't, then it's just an ability check against the DC set by the elves' Dexterity (Stealth) check or passive Stealth score if the elves are hiding in an ongoing basis. The orcs must meet or exceed the elves' result in the former or exceed the elves' passive score in the latter.

So you might say the steps for resolving these sorts of situations is:

1. The DM describes the environment.
2. The players describe what they want to do.
3. The DM decides if the outcome is uncertain.
3a. If certain, skip to 4.
3b. If uncertain, the DM decides if what the player described is a task being performed repeatedly.
3c. If it is, then a passive check is called for.
3d. If it isn't, then an ability check is called for.
4. The DM narrates the results of the adventurers' actions.
5. Repeat.