D&D 5E Perception vs Investigation

[Fralex]

I've talked about this before in other threads, but because I use the Variant rules for aligning a skill to any ability score depending on the situation... I use both WIS and INT for Perception and Investigation. WIS is used for the Passive use of both skills, INT is used for the Active use of both skills. Perception is used for the detection of any living thing that is trying to hide-- anything that moves around, makes noise, can make tracks etc. Investigation is used for any non-living hidden thing-- traps, secret doors and so forth.

If someone has used Stealth to hide, you'll notice him using Passive Perception (10 + WIS + Perception). To notice a tripwire across a hallway automatically uses Passive Investigation (10 + WIS + Investigation). If you use an Action to search for someone who is hiding, that is Active Perception (d20 + INT + Perception). If you use an Action to search for a secret door or trap, that is Active Investigation (1d20 + INT + Investigation.)

This has worked very well for my tables, and my players always know which ability scores and which skills apply to which situations.

This is the clearest interpretation I've seen yet. So... for those of us who aren't using the alternative skill rules, it would come out to:

Perception: Attempt to notice a living thing that is hidden from you.
Perception, Passive: Sets the DC for a check made by a creature attempting to hide from you.
Investigation: Attempt to locate a hidden object.
Investigation, Passive: The highest finding DC you can pass automatically to notice a hidden object.

 

[Celtavian]

I've never understood Perception being a skill only a few classes have access to. I prefer games that consider Perception an innate part of the character. I don't think anyone could survive for long as an adventurer without Perception as it is used in D&D. I'm going to make it available to everyone.

 

[bolo__]

I've never understood Perception being a skill only a few classes have access to. I prefer games that consider Perception an innate part of the character. I don't think anyone could survive for long as an adventurer without Perception as it is used in D&D. I'm going to make it available to everyone.

How is it not available to everyone? Do you mean being able to be proficient in perception? There's no skill a PC doesn't have "access to", they just may not have a very good modifier for the D20.

 

[Celtavian]

How is it not available to everyone? Do you mean being able to be proficient in perception? There's no skill a PC doesn't have "access to", they just may not have a very good modifier for the D20.

Yes. Proficient.

Being ambushed in real life is a death sentence in combat. In D&D you would think it was a minor inconvenience the way they handle Perception. No one that was wandering around in dangerous areas where combat was expected on a constant basis would lack Perception. If they did, they wouldn't last long.

 

[DEFCON 1]

This is the clearest interpretation I've seen yet. So... for those of us who aren't using the alternative skill rules, it would come out to:

Perception: Attempt to notice a living thing that is hidden from you.
Perception, Passive: Sets the DC for a check made by a creature attempting to hide from you.
Investigation: Attempt to locate a hidden object.
Investigation, Passive: The highest finding DC you can pass automatically to notice a hidden object.

Yup. You could use my split of Perception (hidden living things) and Investigation (hidden inanimate things) even without doing the WIS / INT variant. So here's how it would look...

If a person, animal, creature monster etc. is hiding somewhere out and around you... you always have a default "spidey sense" passive perception to notice them of 10 + WIS modifier (plus your proficiency bonus if you have proficiency in the Perception skill). Anyone who is out there has made a DEX check (plus Stealth if applicable) to try and gain the Hidden condition-- your Passive Perception score is the DC they need to reach to avoid being noticed out of hand.

If the person's DEX (Stealth) check is higher than your Passive Perception... they are Hidden from you. On your turn, you can use your Action to make an Active Perception check-- Roll a d20 + DEX modifier (plus your proficiency bonus if you have proficiency in the Perception skill). Obviously, at the barest minimum you want to roll above a 10, since that's the only way to reach a number you haven't already gotten via your passive perception. If your WIS (Perception) check reaches the DEX (Stealth) check of the person Hiding, you have noticed where they are and can target them.

For traps and secret doors, using INT (Investigation) is the same thing. Walking around, a character has a passive sense to notice weird markings, objects that seem out of place, scuffs, scrapes, glints of light etc. This is your passive investigation and is 10 + INT mod (plus prof bonus if proficient in Investigation.) Any trap or secret door/panel that has a DC less than your passive investigation is noticed automatically. That tapestry that covers the secret door bulges where the doorknob is and isn't really hidden well at all. No need to roll-- you find it automatically. But for other things-- that pit trap which is built extremely well and not found via a simple tapping with a 10 foot pole-- you only can find it by using your Action to make an Active check, which is a d20 + INT mod (plus prof bonus if proficient in Investigation.) If you roll high enough to surpass the DC, then you find it. And in the case of traps or locked secret doors, once you have found it, it will then take a DEX (Thieve's Tools) check to disarm / unlock it.

That's all there is to it.

Now that being said... here's a few other reasons for what I personally do to add onto or explain this. The reason I use the Variant rules for skills is because I go back to the perhaps very first playtest packet, where they explained why they were using the six ability scores for checks. In that original document explanation-- the six ability score were and ARE the checks. In the way they were designing the game... they weren't having people make Perception checks to find something, people make WIS checks to find something. Likewise, to unlock a door you make a DEX check (not a Thieve's Tools check). To jump a gap is a STR check (not an Athletics check). To convince the shopkeeper to give you a discount is a CHA check (not a Persuasion check.) So in that manner of looking at the game... I see any passive "spidey-sense" noticing of weird sounds, out of place objects, strange reflections or whatever-- things that just tickle you at the base of the neck that tells you something is wrong... all of those are WIS checks. By the same token, any time you make an active search to find something, using clues and deductive reasoning-- that uses your INT.

Then on top of all of these six different checks... everyone has those few things they have a bit more knowledge about-- perhaps physically, intellectually, or spiritually. Those things (the things you have Proficiency in) can add a bonus to any of the six checks you are making. And they do not have to line up one-for-one. If you have proficiency in Religion... sure, to recall lore about a god would be an INT check (and you could add your prof bonus to it.) But if you were talking with a high-ranking church official and wanted to convince them to make a ruling by using some esoteric doctrine you know about, you could make a CHA check (plus your Proficiency bonus for having Religion.) Swimming is usually a STR (Athletics) check. But if you are swimming through a long underwater tunnel, I might ask you to make a CON check to hold your breath (and let you add your prof bonus for Athletics to exemplify your better ability to swim faster.) Or if you are trying to convince someone you are someone else, ordinarily that would be CHA (Deception). But if you had a illusion over you to make you seem like an ogre for example, you could attempt to fool someone by trying to lift a large object and make a STR (Deception) check.

These are all examples of why I prefer using the Variant rules. I always ask for Ability Checks, and the players can then try and get me to allow them to use a specific proficiency they have (if they can illustrate to me how and why it should apply.)

 

[DEFCON 1]

Yes. Proficient.

Being ambushed in real life is a death sentence in combat. In D&D you would think it was a minor inconvenience the way they handle Perception. No one that was wandering around in dangerous areas where combat was expected on a constant basis would lack Perception. If they did, they wouldn't last long.

Well, the theory of the 5E system is that everyone does notice things. That's why the game asks them to make WIS checks. It's the Wisdom Ability Check that is important part of the system, and thus all adventurers do have it. They all can notice threats that are out there by rolling a d20 + WIS.

However, there are a select few out there who are exceedingly good at noticing even the smallest things, things that even highly-trained adventurers might miss. Elves and certain adventurers that have the eyes of an eagle and the ears of a cat. They're the special ones. And those are the characters who have "proficiency" in Perception. So while every adventurer can and does noticing things (making WIS checks), only a select few have that hypersensitivity that allows them to add their proficiency bonus on top of it.

That's the theory of how 5E was supposed to work anyway.

 

[jayoungr]

I tend to view Perception vs Investigation as Doctor Watson vs Sherlock Holmes. The former is an army doctor with good eyes and quick to react to danger. The latter is observant and pays attention to what he sees.

That sounds great except that I can't picture how it would play at the table: a successful investigation roll means I (as DM) tell the player "You realize he must be the murderer because the mud on his boots is only found in the jungles of Xbyssinia where the poison came from, and it's still wet"?

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

Investigation: allows you to use deductive reasoning that the room is smaller on the inside than the outside would suggest

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

Similarly:

Investigation will reveal that silver coins are conspicuously absent from the gambling tables

Why couldn't that just be noticed with perception?

I haven't seen anything that would suggest Investigation is a social skill.

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've talked about this before in other threads, but because I use the Variant rules for aligning a skill to any ability score depending on the situation... I use both WIS and INT for Perception and Investigation.

I'm curious, are these variant rules in the DMG? If so, which section? (I may well have missed this on my skim through the book.)

 

[I'm A Banana]

I harken back to the ability scores:

Perception, being Wis, is about intuition and instinct. You will notice if something his hidden from you, but that is probably about all you will notice - a movement, a darting figure, a discoloration in the floor, etc.You can "actively" use Perception to basically pay close attention to what you are hearing and seeing in the moment - you shut out distractions and really listen for a moment. It is using a heuristic - is anything unusual about what I'm experiencing right now?

Investigation, being Int, is about precision and detail. It is using an algorithm, checking methodically each thing and seeing if it meets certain established criteria. It isn't ever passive (because you need to take time to apply it), and it involves your whole body, prodding with fingers, sniffing the area, walking around and viewing it from other perspectives, etc. It reveals substantial information, because that is its purpose: not "is something weird?" but "what am I actually looking at and how does it compare to how I imagine it should be?"

In a room with a trap, there's three characters. The first might find it with Passive Perception - "You notice something odd about the tiles to the north of the room. Not sure what it is from here, though." The second might find it with active Perception - "You take a minute and scan the room. You notice something odd about the tiles in the north of the room - looks like one is slightly discolored." The third might find it with active Investigation - "You canvass the room in detail. When you reach the north side of the room, you gently prod one of the tiles with your feet, one that is slightly discolored, and you hear a mechanical clanking noise in the walls. The tile is clearly linked to a trap, which will go off when enough weight is applied to it."

IMC, Investigation tends to be more useful than Perception when searching an area, but it won't save your hide when the goblins are leaping out of the bushes, because it relies too much on methodical, detailed analysis. Perception is your friend there, because that's how you notice the slight sound of a dagger being unsheathed.

I've never understood Perception being a skill only a few classes have access to. I prefer games that consider Perception an innate part of the character. I don't think anyone could survive for long as an adventurer without Perception as it is used in D&D. I'm going to make it available to everyone.

I tend to agree - those characters who are especially keen and quick on the uptake could really use some other mechanic to distinguish them. But then I'm skeptical of the idea of skill proficiencies to begin with.

 

[Jester David]

That sounds great except that I can't picture how it would play at the table: a successful investigation roll means I (as DM) tell the player "You realize he must be the murderer because the mud on his boots is only found in the jungles of Xbyssinia where the poison came from, and it's still wet"?

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

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.

 

[DEFCON 1]

I'm curious, are these variant rules in the DMG? If so, which section? (I may well have missed this on my skim through the book.)

I'm pretty sure it's right there in the Player's Handbook. One of the sidebar boxes in and around the skill section that just says that the Variant is to not have a set ability score aligned to every skill, but choose the score that makes sense for the check and add the prof bonus if the skill aligns to what you're doing.