D&D General Perception vs Investigation

[Clint_L]

I like having investigation be useful against traps specifically because rogues tend to have decent intelligence and often dump wisdom, so it improves their scouting ability. Plus, it then pairs well with sleight of hand to disarm the trap they found.

And there are some situations where I would rule that players can choose which to use, just as in some situations you might let players pick athletics or acrobatics. For example, maybe there's a secret door, and perception could let them notice something off in the environment that clues them in - a draught or something - while investigation might reveal the hidden mechanism, like the book that's really a lever.

But I don't think it matters too much how you rule, as long as you are consistent.

 

[EzekielRaiden]

Okay... so, correct me if I am wrong here. I'm used to how the old D20 system handling perception. The perception skill was used for finding traps, secret doors, that journal hidden in the alchemists lab, whether you were being followed and spotting ambushes on the road ahead. D&D 5th adds the investigation skill which feels like it is used when asking questions around town, spending the day in the great library to find out the history of the mysterious tower or perusing the accounts ledges of the dodgy auction house.

A couple of players in one of my two 2024 campaigns have asked about using investigation to search rooms for secret doors, hidden treasure...etc, when they take their uninterrupted time rather than using perception. I get what they are saying, in that they have all the time they need to do so thus making investigation more appropriate, but my DM brain finds that clunky when perception already exists for that purpose. Even if I give them advantage for taking their time.

Thus far I have said yes, fine, but is this right and my brain is just stuck with concepts from an older edition?

Perception: Noticing physical observables (sights, smells, naturally-occurring sounds, etc.)
Investigation: Piecing together circumstantial evidence into a resultant conclusion

For me, the difference is that Investigation is about proposing a theory and taking actions which generate evidence for or against that theory, while Perception is straight-up just what do your senses detect. Perception matters most when you have no idea what in particular you're looking for and are just taking in the scene. Investigation matters most when you know (or think you know) what you're looking for, but need to confirm that it is in fact actually here as opposed to somewhere else.

Examples include...

• Trying to determine where a secret door is. Perception: noticing the scrape marks on the floor where the bookcase swings open, seeing places where dust has been pushed around, listening for any unusual sounds. Investigation: Examining the bookshelf to identify a book touched/moved more than others, measuring the length of a room vs its exterior to find the false wall, tapping walls to find hollow ones, etc.
• Tracking someone/something. Perception: detecting the subtle indentations in grassy ground, hearing footsteps if the target is close, smelling the scent left behind (e.g. perfume, smoke, etc.) Investigation: matching fingerprints or shoe markings, collecting witness testimony, checking which direction branches/reeds/etc. are broken, using an accurate map to determine viable routes of escape.
• Finding traps. Perception: seeing the tripwire, smelling the acid, feeling the indentations in the floor where boulders have fallen. Investigation: Testing floors for whether they sound hollow, checking for irregularities in tile patterns, distinguishing different types of soot-stains (e.g. torch-smoke vs fire-trap scorching),

It can also help to point out things that one can't be used for, but the other can. Investigation is a generic research skill--if you aren't looking for historical information or some specific bit of lore from Arcana or Religion or the like, then Investigation is your go-to for "looking up details to assemble an argument"--which Perception should be useless for. Conversely, Investigation is worthless for the purpose of keeping watch, while Perception is obviously useful--do you notice things approaching your camp?

Investigation applies reasoning to a situation, sometimes with testing of a hypothesis, to draw a conclusion. Perception takes in the scene as it already is, with only whatever minimal interaction is necessary. I really do think the "knocking on the wall to hear if it's hollow" thing is a good example illustrating the division. I would not, personally, consider that action one of "perceiving", but rather of "investigating"--you're testing the world to see if it yields useful information, not just gleaning the useful information available on the surface.

 

[Retros_x]

For me Perception = Perceive sensory information.
Investigation = Deduce Information, decipher code, understanding how a trap or mechanism work etc.

So perception is to realize something is out there, investigation is "what does it mean?" Perception is feeling a slight draft from the wall, Investigation is how to open the secret door. Perception is seeing the thin wire on the floor, Investigation is how you can disarm it.

Perception is more what or where is something.
Investigation is more how does something work or why something happens.

But the biggest difference for me is the implications in what layer of game they operate. Perception operates on interaction with the world. You basically get more info about the scene, more decision points on a successful perception checks.

Investigation is more about your characters understanding of the world and thus it often acts as a bypass to player skill and intelligence. If a player doesn't understand a puzzle or mechanism, they can just roll for investigation and the DM tells them on a success.

Thats why dedicated puzzles feel so weird in 5e to me. Suddenly player skill is needed and most DMs don't let players bypass a puzzle with a high Investigation check, maybe they give a hint and thats it.

 

[DragonLancer]

Thanks for your input everyone. That has clarified it better for me now. I just need to get my head out of how previous editions did it.

 

[CreamCloud0]

Personally, I use Perception for detecting sensory information (which includes both searching and spotting), and Investigation for making logical deductions based on sensory information.

yeah i second this description, Perception is sensory, it's used to notice things, Investigation is closer analysis, it's used to figure things out or filter information, there is some overlap in what they can be used to achieve but they are different.

 

[LuisCarlos17f]

Perception is to discover traps in the dungeon or food in the forest. Investigation is to discover details that may be possible clues.

Perception is to find a cat. Investigation is when you notice that cat has got three colors then it is female or a chimera (when two embrins are fused).

Perception is to discover a taint in the dress. Investigation is knowing if the taint is blood or wine.

 

[Shiroiken]

While not necessarily RAW, I tend to break them down as:

Perception: noticing something not obvious
Investigation: realizing why something obvious is actually important

This can allow the skills to be used for the same things, depending on how they're used. For example, both find traps in different ways: perception notices a tripwire, while investigation points out that certain flagstones being unused means they're pressure plates. Both can find secret doors, by either tapping on walls (perception to hear hollow spots) or examining the area (investigation to find the trigger). A false bottom can be deduced by the short depth (investigation) or the edge spotted (perception). This allows characters with either to feel useful.

 

[Bae'zel]

I think I broadened the applicability of Investigation because of how Perception is overused.

Nowadays I work like this: using your senses to detect something at a distance? Perception. Using your senses to detect something very close? Investigation.

If I went a bit farther, I’d probably ditch Perception as a skill altogether and have it relegated to “Passive” permanently. But that’s probably gonna ruffle some feathers. Good news though: I’d let someone use their Wisdom with Investigation under the right circumstances.

 

[TaranTheWanderer]

Perception is to discover a taint in the dress. Investigation is knowing if the taint is blood or wine.

While I think it's supposed to be used in this way, In my experience, this never happens. How I've always seen it played out is,

"You succeed on your perception check and notice blood on the dress."

It's almost never two rolls and, therefore, the Investigation use gets ignored and Perception becomes the catch-all, most useful skill.

 

[aco175]

It's almost never two rolls and, therefore, the Investigation use gets ignored and Perception becomes the catch-all, most useful skill.

I was thinking the same for Perception for noticing the scrape marks on the floor where the bookcase looks like it swings open. So now the players know/think there is a secret door there and must roll an Investigation check to determine that you push a book, or there is a latch, or even just pull it and it opens. Would you just skip the second roll figuring that once they know where it is, they eventually will be able to open it? Give advantage since they know the exact spot to look? Just make the check Investigation to begin with?

Is there a difference with concealed doors and secret doors? I tend to make Perception to notice concealed doors behind a curtain or something. The two skills get blurry.