D&D 5E Perception, Passive Perception, and Investigation

[Azzy]

Inspired by the Cloak of Elvenkind thread, I've finally decided to address my biggest source of confusion in 5e. Almost seven years in, and I still get occasionally confused about when Passive Perception is used in lieu of normal Perception. It seems to me that it would be when walking by secret doors, noticing traps or ambushes—sort of like the elf's ability to notice secret doors in AD&D, but that begs the question of when does "active" Perception get used and why?) Then there's Investigation. When does it come into play instead of using Perception? When I search a desk, am I using Perception or Investigation? Lastly, why are the rules for these things so virtually non-existent?

So, okay comunity, what are your thoughts on the matter? How have you parsed these things? And where upon the rules do you base your interpretation upon?

 

[clearstream]

Inspired by the Cloak of Elvenkind thread, I've finally decided to address my biggest source of confusion in 5e. Almost seven years in, and I still get occasionally confused about when Passive Perception is used in lieu of normal Perception. It seems to me that it would be when walking by secret doors, noticing traps or ambushes—sort of like the elf's ability to notice secret doors in AD&D, but that begs the question of when does "active" Perception get used and why?) Then there's Investigation. When does it come into play instead of using Perception? When I search a desk, am I using Perception or Investigation? Lastly, why are the rules for these things so virtually non-existent?

So, okay comunity, what are your thoughts on the matter? How have you parsed these things? And where upon the rules do you base your interpretation upon?

Preface: I like to make all abilities useful, and I like to lean hard away from the fab-four skills (Athletics, Perception, Persuasion, Stealth).

I suspect the most honest way to describe my ruling is that Perception is used to notice creatures, and Investigation is used to deduce the implication of artifacts. That means it is a perception check in my game to notice a creature sneaking up on you, and an investigation check to spot a trap or secret door. It is worth noting that the designers of official material don't use investigation in this way. In published adventures, a character can typically ride Perception all the way through.

As for passive checks, I use them as a floor for Perception and Investigation, so that normally players automatically get some environmental information. That might be at disadvantage (i.e. -5) if they are rushing or otherwise hindered. Or forestalled completely in some circumstances. It means that characters with Observant are hard to sneak up on even if not keeping an active lookout and so forth. I think this plays well because if it isn't a floor, players can hinder themselves by taking action to keep a sharp lookout or whatever. I prefer that they can at worse do just as well as they would have if being ordinarily cautious.

 

[Coroc]

Inspired by the Cloak of Elvenkind thread, I've finally decided to address my biggest source of confusion in 5e. Almost seven years in, and I still get occasionally confused about when Passive Perception is used in lieu of normal Perception. It seems to me that it would be when walking by secret doors, noticing traps or ambushes—sort of like the elf's ability to notice secret doors in AD&D, but that begs the question of when does "active" Perception get used and why?) Then there's Investigation. When does it come into play instead of using Perception? When I search a desk, am I using Perception or Investigation? Lastly, why are the rules for these things so virtually non-existent?

So, okay comunity, what are your thoughts on the matter? How have you parsed these things? And where upon the rules do you base your interpretation upon?

This is a really easy one, no way confusing at all.

Whenever a PC announces he is looking out for things he is in for an active perception roll.
Whenever a player finds something which can be examined, and announces he does so, he is in for an active investigation roll or sometimes history, nature, arcana or religion instead.

A good example for investigation applying is an -already found- trap being analyzed.

Whenever none of the players is actively looking out for something obscure or hidden, but something being present, the dm can roll in secret vs the players passive perception or preset a threshold for that purpose, so he does not have to give away that there might be something hidden, just by asking for a check.

 

[Asisreo]

Inspired by the Cloak of Elvenkind thread, I've finally decided to address my biggest source of confusion in 5e. Almost seven years in, and I still get occasionally confused about when Passive Perception is used in lieu of normal Perception. It seems to me that it would be when walking by secret doors, noticing traps or ambushes—sort of like the elf's ability to notice secret doors in AD&D, but that begs the question of when does "active" Perception get used and why?) Then there's Investigation. When does it come into play instead of using Perception? When I search a desk, am I using Perception or Investigation? Lastly, why are the rules for these things so virtually non-existent?

So, okay comunity, what are your thoughts on the matter? How have you parsed these things? And where upon the rules do you base your interpretation upon?

Passive checks are just like any other check, only relevant when the DM calls for them. They are not always on.

Passive Perception is always on when in combat, but not when you're pre-occupied with something else or adequately distracted.

Perception is your ability to use your senses to detect something. Therefore, you use it to sense when something is nearby. Investigation is used to use reasoning in order to connect the dots about clues in a situation. You use Perception to find the knife and investigation to realize who's it is and what its used for.

 

[DEFCON 1]

I'm also a diehard for what @clearstream put forth. In my games, Perception is for finding creatures that are hiding, Investigation for finding objects that are secret or hidden. Easy, simple, and takes no time in knowing which one to use in whatever situation we are in.

As far as Passives are concerned... I just think of them as the target DCs of what my NPCs are using skills against. Just like when the players use their skills against target DCs I have established. So if my goblins are trying to hide, they make Dexterity (Stealth) checks and the DC to avoid notice is the Passive Perceptions of the PCs. Likewise, if I place a secret door in a dungeon, I'll roll an internal "behind the scenes" check (probably something like Intelligence (Deception) or something) to represent how well the designer of that secret door did in masking it from view (and thus creating the DC). Then if any of the PCs walk by it, their Passive Investigation might notice it if the "original designer" did a really bad job of making it secret.

But of course if the Intelligence (Deception) "check" was good and the DC for that secret door is high enough that no PC's Passive Investigation notices it with no active action on their part... they as characters are still allowed to make a choice to actively look in an area to try and find it. At that point, the PCs roll Intelligence (Investigation). And since passives are 10 + the modifiers... the PCs have about a 50% chance to roll higher than 10, and thus their checks to find the secret door improve. If they roll under 10, then it doesn't matter... their active looking just did not do any better than what they already passively sensed.

 

[Bayushi_seikuro]

Personally, I also like Jeremy Crawford's personal feelings on Passive Perception - Passive Perception/Investigation/etc is the base floor for your roll, a minimum. So, even if you roll a 2, you're not less-aware than you would be if you hadn't had to roll.

 

[Minigiant]

Perception is for detecting where hidden objects and creatures are based on senses.
Investigation for deducing where hidden objects and creatures are based on clues.

You use Perception to find the hidden goblins via their noises and image.
You use investigation to find the hidden goblins via chairs they moved before hiding.

Active Perception/Investigation checks are either initiated by character looking or at a time where the action could affect the check (aka combat)
Passive Perception/Investigation floors are either initiated by character hiding or when the character becomes close enough to sene the hidden object or character.

 

[jgsugden]

Intelligence/Investigation vs Wisdom/Perception: Wisdom reflects how attuned you are to the world around you and represents perceptiveness and intuition. Intelligence measures mental acuity, accuracy of recall, and the ability to reason.

I use Wisdom and Perception rolls for discovering if, and Intelligence rolls (of all types) for discovering what.

Discovering if tells me whether something is realized or perceived. It doesn't generally explain the meaning of what is discovered. A perception check will allow a player to notice the footprints in the rug, or hear the breathing. It will give facts, not conclusions.

Discovering what gives more substantive answers. An intelligence/investigation check would allow a character to deduce that those footprints are an invisible creature, or are an illusion, or are from a ghost, or are whatever else they could be.

Investigation is used to determine things that have layers. A knowledge skill (arcana, history, religion, nature) will give you facts, but investigation is the primary skill for figuring something out, connecting the dots, and putting together information.

Passive Rolls: Passive checks can represent the average result for a task done repeatedly, such as searching for secret doors over and over again, or can be used when the DM wants to secretly determine whether the characters succeed at something without rolling dice, such as noticing a hidden monster. There are specific rules for hiding that are unique to hiding and passive perception - stealth rolls are opposed by passive perception, explicitly (unless the target is actively using their action to look).

I use passive scores as a floor for ability scores when a PC is not focused on something else. If they are focused on something, then there is no floor on a roll. If you're trying to jump over a pit and focused only on doing so, you have a higher floor on it than if you did it in the middle of combat. If you're negotiating a deal over a cup of tea, you're going to have a higher floor on your persuasion than if you plead with someone to stop attacking you.

Clarifying note: A lot of situations can be approached with an array of options. I listen to what the characters are doing when they're telling me something (as opposed to when we're using passive perceptions, etc...) to determine the roll to be made. It is the character actions that drive whether wisdom or intelligence roll.

 

[Asisreo]

Investigation for finding objects that are secret or hidden.

But hidden objects are explicitly called out as using perception in the PHB.

FINDING A HIDDEN OBJECT

When your character searches for a hidden object such as a secret door or a trap, the DM typically asks you to make a Wisdom (Perception) check. Such a check can be used to find hidden details or other information and clues that you might otherwise overlook.

In most cases, you need to describe where you are looking in order for the DM to determine your chance of success. For example, a key is hidden beneath a set of folded clothes in the top drawer of a bureau. If you tell the DM that you pace around the room, looking at the walls and furniture for clues, you have no chance of finding the key, regardless of your Wisdom (Perception) check result. You would have to specify that you were opening the drawers or searching the bureau in order to have any chance of success.

It also clearly outlines Investigation

When you look around for clues and make deductions based on those clues, you make an Intelligence (Investigation) check. You might deduce the location of a hidden object, discern from the appearance of a wound what kind of weapon dealt it, or determine the weakest point in a tunnel that could cause it to collapse. Poring through ancient scrolls in search of a hidden fragment of knowledge might also call for an Intelligence (Investigation) check.

I get where you might be coming from, but investigation isn't for seeing the location of hidden objects, its deducing the location through a logical process.

"The room adjacent to use has no other exits or entrances on any side except for the side connected to this wall in this room, therefore, the secret door must be on this wall and is likely behind the tapestry."

 

[Inchoroi]

In my games, it breaks down like this:

Passives: Passive scores are your minimum; i.e. you can't roll lower than your passive. I do it this way because I can apply it to all skills; your wizard rolled a 7 Arcana, but your "passive" is 16, so you still get something for having taken that proficiency.

Perception: Perception is used to notice things that are unusual; you might not know what that thing is, but you know that its weird. For example, you roll a Perception check to examine a section of wall and realize that its weird.

Investigation: Investigation is used to determine how a mysterious thing works. This skill is used to deduce how to open a secret door that isn't locked, for example, such as finding the small hidden button worked into the floorboard. I might give a thieves' tools check if no one has Investigation, but since my players know of my desperate love of mysteries, they almost always take Investigation.