D&D 5E Perception vs Investigation

[MARCVS AVRELIVS]

I'm thinking maybe it works a bit like that sequence in WATCHMEN where Rorschach find The Comedians costume. Rorschach tells the DM he's checking out Edward Blake's apartment. The DM gives him a quick description - regular place, pics on the wall, wardrobe, broken furniture. Rorschach says he's looking for anything unusual, makes his Perception check. DM says the pics on the walls are all Edward Blake with politicians, the wardrobe is full of clothes but something's not right with it. Rorschach says he's going to check the wardrobe closer and makes an Investigation check. DM tells him he finds a secret compartment, and inside is the Comedian costume. Hurm.

You search the room (Perception), the DM tells you if you find anything interesting, and then if it's not something immediately obvious, you have to follow up with Investigation to figure it out.

Players: We enter the room.
DM: *Checks passive perceptions* It's a 30' x 30' room, with a desk on the south wall, and pair of beds on the east wall. EagleEyes, you spot a goblin crouched down behind the desk.
Players: *after fight* We search the room and the goblin. *roll Perception*
DM: You find a bag of coins in the desk drawer, a locked chest under one of the beds, and EagleEyes, you find a secret door in the south west corner.
EagleEyes: Can I open the secret door? *rolls Investigation*
DM: You notice scratch marks on the wall by a nearby torch sconce, and figure out that twisting it is what opens the door.

OR EagleEyes blows his investigation...

DM: There's no obvious way to open the door.
EagleEyes: I pull out my thieves tools, and try to open the secret door. *Tools check*
DM: You get your tools in the cracks, shimmy them around, and hear something click. The door opens.

I dunno, I think that's how I'm going to handle it.

 

[Tormyr]

At the risk of derailing things slightly, how is everyone handling the old "Gather Information" skill check from 3.5? I have been using Charisma (Investigation).

 

[Quickleaf]

Also, some of the examples of investigation rolls seem like they should be perception rolls to me. For instance....

Why is that deduction and not observation? It seems to me like differences in size could just be noticed.

Ok, so with a room that is smaller on the inside than the outside (let's say it not drastic and is meant to tip the players off to the presence of secret rooms in the architecture), here is what I'd do...

Perception: Observed phenomenon only, like the faint outline of a door or scuff marks onthe floor (from a secret door being opened), or tapestry weathered especially on one side about shoulder height where NPC grasped it and pulled it aside (revealing a concealed passage). Information in parentheses the DM would not share with the player- the player would need to discover it on their own.

Investigation: Deductions and conclusions based on previous details or knowledge, like realizing on their map (whether physical or mental) that 20-ft of space is unaccounted for. The DM would also offer a leading remark, such as "20-foot thick walls would seem like overkill to you" or outright say "the inside space is smaller than the outside, and you suspect there are secret rooms close to the outer wall" (depending on how the group likes to play).

Similarly:

Why couldn't that just be noticed with perception?

Perception is about noticing presence of creatures and things. Noticing the absence of something implies that you are using logic about why that absence is significant or you have a reason to be looking for the absence that thing based on a hunch or prior information. So here's how I'd use the two skills in this case...

Perception (about what's happening at the gambling tables): ...the shady players put up bets with mounds of electrum, gold, and platinum, rare jewels, copper urns, and strange deep purple gems that seem to slightly glow from the corner of your eye... (recognizing the absence of silver is left to the player)

Investigation (examining a game closely, maybe following a hunch the gamblers are more than they seem): Something strikes you - no silver is traded whatsoever, not as coins, trade bars, art objects, or jewelry. The disdainful glance the player across the table gives your silver bracers confirms that these men seem to have an aversion to silver.

I could imagine calling for an Investigation check where I would have asked for Gather Information in other editions--do others agree with that? If so, that gives it some social application.

I think that would be reasonable.

I do worry about the issue of "clue blocking" when the DM presents information needed to continue the adventure behind a skill check like Gather Information or Investigation or Streetwise. Obviously, that can be avoided thru good design/DMing, but it's a problem to be aware of & suggests the type of information that Gather Information or Investigation or Streetwise should provide.

 

[Tormyr]

Perception is about noticing presence of creatures and things. Noticing the absence of something implies that you are using logic about why that absence is significant or you have a reason to be looking for the absence that thing based on a hunch or prior information. So here's how I'd use the two skills in this case...

Is this maybe a bit too restrictive? If I recall correctly, the pit traps in the DMG use perception to notice the absence of foot traffic on the rugs covering the trap.

 

[Quickleaf]

There's very little I would rule as being noticeable via Investigate that a character wouldn't be able to catch through Perception. I view it mostly as a matter of time. Perception is fast, while Investigate is slow. Perception is also passive automatic, while Investigate is active. This is the big difference.

You get a Perception check to notice things around you, like enemies sneaking up for an ambush. You see things out of the corner of your eye. If you actively look around, you're Investigating.

Actually, I use Perception and Investigation differently than you do. From my perspective, you're jumbling active Perception checks, passive Perception score, and Investigation checks. Here's how I'd handle your examples...

Passive Perception: If the PC has no reason to be alarmed, is walking along, and you want to see if they notice enemies lying in ambush or not. Compare to the enemy's Stealth check.

Active Perception: If the PC has a reason to be alarmed and the player asks to make a Perception check to notice something in particular; asking if they are being followed or if there are signs of snipers in the trees could both be used as lead-ins by the DM to reveal the shadows of hidden creatures in the forest ahead.

No use for Investigation is indicated in this example.

Spotting the tripwire while you're walking is a Perception check. Stopping to look for traps is Investigation. Noticing the presence or absence of something is Perception. Noticing details is all Investigation.

I'd say spotting the tripwire while walking is probably a passive Perception situation, because the DM to determines wants to secretly determine if the PC notices, and calling for a check reveals that there's something to discover.

Stopping to look for traps is an active Perception check. As DM I'd report direct observable phenomenon with as few inferences as I can manage. "One flagstone depresses slightly when pressed, and a faint whirring sound like a spinning whetstone or blade comes from the long narrow holes cut thru the ceiling that you assumed were murder holes."

Investigation would enter the picture if the PC tries to figure out how the trap functions, clues about how they might disable it, or clues about who made it and for what purpose. For example: "Lifting the flagstone up slightly with help from your friends you find the bottom is bolted to a chain which seems to jog to the right under the floor. Moving aside some crumbling stones, you peep thru a crack in the wall to reveal a chain and an anchor block. When the flagstone is depressed, the chain slackens, freeing the anchor block which you suspect is the fulcrum causing the blades hidden in the ceiling to swing down. Judging by the size and estimated weight of the anchor block, you'd guess whatever blades are hidden in the ceiling couldn't be longer than 5 or 6 feet. Meaning that crawling should avoid them in the 9-ft tall passage."

 

[Quickleaf]

Is this maybe a bit too restrictive? If I recall correctly, the pit traps in the DMG use perception to notice the absence of foot traffic on the rugs covering the trap.

There's definitely grey area.

After all, there's only a little difference between saying "You see an unsullied rug in practically brand new condition save for a thin layer of dust" and "You see an unsullied rug whose layer of dust suggests it hasn't seen foot traffic for months." The first example suggests the conclusion (no foot traffic) that the second example spells out, though could both be considered completely in the realm of direct observation.

My scenario - the thieves gambling hall - had a lot of moving parts and complexity. Noticing the absence of silver is a small detail among a sea of details, and some kind of detective hunch, or logical leap from a past clue, or close observation of the poker game would be needed to pick it up.

A rug, not so much.

In most scenarios I imagine the rug-without-foot-traffic being used (PCs searching a villain's room, a dungeon chamber, or a murder scene), this would either be automatically revealed in the description of the room/the rug or would a low DC Perception check.

 

[Jester David]

Actually, I use Perception and Investigation differently than you do. From my perspective, you're jumbling active Perception checks, passive Perception score, and Investigation checks. Here's how I'd handle your examples...

Passive Perception: If the PC has no reason to be alarmed, is walking along, and you want to see if they notice enemies lying in ambush or not. Compare to the enemy's Stealth check.

Active Perception: If the PC has a reason to be alarmed and the player asks to make a Perception check to notice something in particular; asking if they are being followed or if there are signs of snipers in the trees could both be used as lead-ins by the DM to reveal the shadows of hidden creatures in the forest ahead.

No use for Investigation is indicated in this example.

I'd say spotting the tripwire while walking is probably a passive Perception situation, because the DM to determines wants to secretly determine if the PC notices, and calling for a check reveals that there's something to discover.

Stopping to look for traps is an active Perception check. As DM I'd report direct observable phenomenon with as few inferences as I can manage. "One flagstone depresses slightly when pressed, and a faint whirring sound like a spinning whetstone or blade comes from the long narrow holes cut thru the ceiling that you assumed were murder holes."

Investigation would enter the picture if the PC tries to figure out how the trap functions, clues about how they might disable it, or clues about who made it and for what purpose. For example: "Lifting the flagstone up slightly with help from your friends you find the bottom is bolted to a chain which seems to jog to the right under the floor. Moving aside some crumbling stones, you peep thru a crack in the wall to reveal a chain and an anchor block. When the flagstone is depressed, the chain slackens, freeing the anchor block which you suspect is the fulcrum causing the blades hidden in the ceiling to swing down. Judging by the size and estimated weight of the anchor block, you'd guess whatever blades are hidden in the ceiling couldn't be longer than 5 or 6 feet. Meaning that crawling should avoid them in the 9-ft tall passage."

I tend to view active Perception is any time the character is stretching their senses: trying to see in the distance, trying to track down an odd smell, feeling for a trickle of air denoting a secret passage, trying to hear through a door, etc. Any time the limits of the sense comes into play, where the average person might not be able to automatically detect something. Times, when as a DM, I'd use the term "keen senses".

Investigation tends to be less about what can or cannot be easily seen, and more noticing what is already visible. The subtle clues. The worn patch of the floor denoting sliding stonework, the absence of a wedding band on a finger, etc. Piecing together the evidence of your senses and making connections and inferences. If a player asks the right questions, I'd generally give them the answers to a successful Investigation check. "Are any patches of the wall unusually smooth?" "Are any of the flagstones loose?" Investigation is just your character doing what the player might not be aware of. But in Perception, the character either sees it or doesn't and no asking questions will reveal the answer.

I tend to think of rounds versus minutes. If what you're doing takes longer than an action or two, it shifts from Perception to Investigation. You can glance at a hallway or wall and, if your eyes spot something odd you succeed. But if you stop to actually make a decent check, then it becomes Investigation.

A rogue finding traps, to me, seems very much like an Investigation check. You're looking for clues and signs of the trap. It's a slow, methodical process.

 

[iserith]

At the risk of derailing things slightly, how is everyone handling the old "Gather Information" skill check from 3.5? I have been using Charisma (Investigation).

If the action undertaken to gather information has an uncertain outcome, then an ability check relevant to the method used is called for. In D&D 3.5e, Gather Information was the mechanical resolution for a fiction action that involved "an evening’s time" and "a few gold pieces for buying drinks and making friends," which makes it a time-consuming social activity. That approach, if it has an uncertain outcome, is probably a Charisma check. See also page 62 of the Basic Rules where a Charisma check is called for to "Find the best person to talk to for news, rumors, and gossip."

But it's entirely possible a different approach may call for a different ability check.

 

[iserith]

Passive Perception: "Chuck Dagger moves through the dungeon with his head on a swivel, constantly on alert for hidden threats."

Wisdom (Perception): "Chuck Dagger rifles through the chest of drawers for anything of value."

Passive Investigation: "Chuck Dagger spends a few hours going through boxes full of evidence and tries to piece together a timeline of events preceding the murder."

Intelligence (Investigation): "Chuck Dagger tries to figure out how this trap on the door works."

And every example above assumes that the action Chuck is taking has an uncertain outcome or else no check, passive or otherwise, would be necessary.

 

[Fralex]

There's very little I would rule as being noticeable via Investigate that a character wouldn't be able to catch through Perception. I view it mostly as a matter of time. Perception is fast, while Investigate is slow. Perception is also passive automatic, while Investigate is active. This is the big difference.


You get a Perception check to notice things around you, like enemies sneaking up for an ambush. You see things out of the corner of your eye. If you actively look around, you're Investigating.

Spotting the tripwire while you're walking is a Perception check. Stopping to look for traps is Investigation. Noticing the presence or absence of something is Perception. Noticing details is all Investigation.

So you treat Perception as more of a saving throw than a skill? Something you only do in response to something else?