Perception, Investigation: a Perpetual Imbroglio

Today I want to talk about the difference between two things that are consistently mixed up in D&D 5e: Perception and Investigation.  This is ostensibly a gaming topic, of interest to people who play (or just watch) TTRPGs such as D&D, but I’m going to make an argument that it’s actually rather fascinating from a linguistic perspective as well.  This is one of those rare topics where I can explore language and give gaming advice all at the same time.

So, first of all, what actually is the problem here?  Simply put, D&D characters have skills—certain things that they’re good at, or not so good at—and, when the character attempts to do something (well, something that isn’t swinging a sword or casting a spell), it’s the GM’s job to decide which skill applies.  Sometimes there can be a bit of back and forth on this: for instance, two of the skills in 5e are Athletics and Acrobatics.  Athletics is based on Strength, and it’s what you use when you want to climb, jump, swim, or grapple.  Acrobatics, on the other hand, is based on Dexterity, and it’s what you use when you want to dodge, tumble, or flip.  You could imagine a scenario where a player says what they want to do and the GM says, “great, give me an Athletics check,” to which the player replies: “ummm, can I use Acrobatics instead?” Obviously, they ask this because they have a higher Dexterity than they do Strength, or they’re proficient in the one but not the other.  You could even imagine a scenario where either skill could be used (say, the user wants to negate damage from falling, and they could either employ their jumping skills or their tumbling skills), and the GM might change their minds.  Sometimes the GM just does this not to be a hardass—after all, we’re playing a game here, not trying to outwit each other or trick each other into rolling poorly—but sometimes the GM can see it either way, or the GM is just persuaded of the player’s point of view.  And that’s fine.

What’s less fine is if the GM doesn’t really know which one is the right answer.  As a GM, one needn’t be perfect, of course, but one should strive to understand the things that come up often.  And, if you watch any streaming D&D games (which is easy to do these days), you may see a scenario like I describe above between Athletics and Acrobatics ... but you will almost certainly see one involving Perception and Investigation.

And here’s the thing: once you have a good grasp on the difference between the two, it’s way less common to find a situation where they really are interchangeable.  I can’t count the number of times where I’ve watched GMs—really really good GMs, even—say, “ah, sure, you can use Perception here,” or even (and I shudder to even type the words) “give me a Perception check or Investigation check: your choice.” Now, I’m more of a yell-at-the-screen sort of critic than a post-snarky-corrections-in-the-comments-section one, so, if I want to publicize my opinion on this issue, this blog is where I do it.

Now, I’m hardly the first person to realize this is a problem.  A cursory Internet search will reveal article after article (after article) telling you how to distinguish between the two.  The problem is, most of them give conflicting advice, so they can’t all possibly be right.  This leads to many (many) instances of people on the Internet asking for help ... for which they receive—you guessed it—conflicting advice.  And the problem is, even if you try to find a common thread from all those, you’re probably going to find the wrong one.

See, the general concensus of the Internet is, since Perception is based on Wisdom while Investigation is based on Intelligence, Investigation should only be used to understand the things that you see (using Perception).  Investigation, this line of reasoning goes, is all about drawing conclusions and deductions based on obersvations.  But there’s a fundamental problem with that: it contradicts the actual rules.  Here’s what the rules say about Investigation:

When you look around for clues and make deductions based on those clues, you make an Intelligence (Investigation) check.

So the deducing is part of the Investigation, sure, but so is the looking.  Fine, then: what do the rules say about Perception?

Your Wisdom (Perception) check lets you spot, hear, or otherwise detect the presence of something.

Hmm ... that also seems to involving looking.  No wonder people are confused.

Now, I should first note that neither skill has to involve looking.  You can perceive things with your ears or your nose, and you can investigate things with your hands or your brain.  But those aren’t the cases that confuse us, as it turns out.  If the player says “I listen to see if I can hear anyone following us” and the GM asks for a Perception check, no one is going to try to talk them into Investgation (or at least no one I’ve ever heard of); likewise, if the player says “I want to try to decipher this code” and the GM asks for Investigation, no serious player is going to try to convince them that it should be Perception instead.  It’s only when the visual sense comes into it—and we human beings are primarily visual creatures, so it tends to come into it quite a lot—that people tend to get confused.

As I mentioned, this has been debated a lot.  I wouldn’t want to weigh in if I didn’t feel like I had something new to contribute.  So here’s where I endorse my potentially revolutionary, potentially controversial take on this dilemma: it’s all about the verbs.  And the verb at the heart of this bewildering issue is “look.”

And what’s really fascinating to me is that it reminds me of my high school Spanish.  The way I was taught (and I’m sure it was a gross oversimplification designed to be able to be grasped by teenage brains) is that if you want to say you’re looking at something, you use mirar, but if you want to say you’re looking for something, then it’s buscar.  So when a native Spanish speaker tells you “miré la playa,” you understand that they went to the beach and just enjoyed the view.  But if on the other hand they say “busqué la playa,” then you know that they were trying to find the beach in the first place.  “I looked at the beach” (or “I watched the beach”) vs “I looked for the beach” (or “I searched for the beach”).  This is only hard for us English speakers because we’re so used to having one word for both concepts.  But, when you think about it, it’s actually easier and nicer to have the two different words: avoids any ambiguity.  “What’s the deal with the beach?” “Oh, I’m still looking.” Does that mean you refused to leave the beach because the view is so awesome, or that you can’t figure out how to use the map app on your phone so you never even got there?  No way to tell in English.  But, in Spanish, it wouldn’t even be a question: “todavía miro” and “todavía busco” are two entirely different replies.

I have no way to prove this, but I feel very confident in saying that Spanish-speaking D&D players and GMs have no confusion about Perception and Investigation at all: Perception is mirar, and Investigation is buscar.  Case closed.

But us poor non-speakers of Spanish need some guidance, yes?  Very well then, here’s my advice (to both GMs and players): expunge the word “look” from your vocabulary.  That’s it.  That’s all it takes.  Don’t tell your GM “I want to look and see if I see a clue”; say instead either “I want to try to notice a clue” or “I want to try to search for a clue.” If you can replace “look” with “observe” or “notice,” that’s Perception.  If you can replace it with “search” or “examine,” that’s Investigation.  That’s really all there is to it.

Now, I do want to address another aspect that seems to flummox people: the amount of time taken by the two actions.  One of those links above contains this gem of wisdom:

Often, DMs think that the difference between perception and investigation is simply how long the player wants to take to search. But this is NOT the case.

(Emphasis in the original.)  To which I respond: well, yes ... and no.  What they say is technically true.  The amount of time taken should never be the determining factor in which skill applies.  However, as a practical matter, it really is the case that “noticing” or “observing” typically takes a very small amount of time, while “searching” or “examining” takes much longer.  We could come up with counter-examples, of course: a Perception check to see if you notice anything during your 3-hour turn on watch duty, or an Investigation check to see if you can have a flash of inspiration while examining a puzzle with the walls closing in on you.  But, in general, Perception happens in an instant and Investigation takes time.  Which brings up another thorny issue: doing these things in combat.  See, in D&D a round of combat takes (in theory) 6 seconds.  During those 6 seconds, you can move (up to 30 feet, typically), and take an action, and maybe even take a bonus action (such as hiding if you’re a rogue, or getting in one more punch to the face if you’re a monk), and take a free “object interaction” (such as drawing a weapon or opening an unlocked door).  The main action for the turn thus has to fit in a very small number of seconds, certainly no more than 3.  You are not going to be searching a room in 3 seconds.  Contrariwise, it simply doesn’t take 3 whole seconds to look around and notice something.  I would never charge my player a whole action to take a Perception check in combat, but I would also never let my player get away with an Investigation check in combat, unless perhaps they devoted all their attention to it, and even then it would probably be an astronomically high DC.  Yet making players use their action for Perception is very common in streaming D&D such as Critical Role, and allowing them to do so for Investigation is not unheard of either.  I have to say, these calls don’t make a lot of sense to me.

Of course, several of the links I listed above will tell you that I’m completely wrong about searching for clues being an Investigation check.  Here’s some examples:

... Investigation focuses on interpreting the clues found with Perception checks.

However, the way I think of it is that Perception is to spot something like a clue, and Investigation is to work out what that clue means.

... to draw conclusions from the clues you’ve used perception to gather.

There’s only one problem with this theory: it’s not what the rules say. “When you look around for clues ... you make an Intelligence (Investigation) check” seems pretty clear to me.  I respect the distinction that these authors are trying to draw: a skill based on your Wisdom means you’re using intuition and awareness, while one based on Intelligence means you’re using logic and reasoning.  Unfortunately, trying to get too detailed on things like this is always going to break down.  To return to my first example of conflicting skills, your natural dexterity absolutely impacts your ability to climb, but it’s still an Athletics check; the strength of your muscles is definitely a factor when you’re swinging on a rope like a trapeeze artist, but it’s still an Acrobatics check.  D&D is not a perfect simulation—no TTRPG can be—and sometimes you just gotta go, well, this skill is for this action and this is what ability the book says goes with it ... don’t overthink it.

So, if you play D&D (and especially if you GM it), hopefully this will help you figure out which skill to apply when it seems confusing.  And, even if you don’t, hopefully you’ve had some inspirations as to how the subtleties of language impact every part of our lives: even the most unlikely ones.