D&D Tips: Perception vs. Investigation

The party has finally dispatched the evil priest and scattered his cult, and now have the run of his dark sanctum. It may be that he has stashed treasures in the—
“Perception check to search the room!” declares the rogue, throwing the die.
“Hang on”, says the DM, “you—”
“Ugh”, the rogue groans, “it’s a 2. Can I use my passive Perception instead?”

“I’m going to try Investigating instead” shouts the wizard.
“But you’re trying to perceive your surroundings”, interjects the fighter, “you should roll Perception”.
“No”, says the wizard, “I’m looking at something specific, so it’s Investigation!” The die flies into the air as the DM sinks his head into his hands, defeated.

Skill checks are an important part of the game. They provide a framework to test the talent and training of a character in an endeavour that has a chance of failure. More so than any others, the Perception and Investigation skills are often the source of significant confusion. This article helps resolve that confusion and offers some important advice on running skill checks in your game.

Using Skills

There are a few important clarifications to make about skill checks before we begin.

The first point is that players should never be declaring that they are rolling a skill check. It’s not their prerogative and it often results in scenes like the one that played out above, where the DM has to fight for control of the table. A player’s role is to describe what actions their character is taking as clearly as possible, allowing the DM to determine what happens. As an adventurer’s life is rarely dull and they often find themselves in high-pressure situations or encountering strange sights, DMs will frequently call for skill checks to measure how well they perform.

For example, while it’s an easy thing to find lore in a library, the weaknesses of an ice demon may be a challenge to recall in the midst of battle. Likewise, an accomplished acrobat can probably perform a backflip with ease on even terrain with only a few moments of preparation, but to try to wall-flip over a bunch of debris in a full-on melee might require a bit of luck. An Intelligence (Arcana) and a Dexterity (Acrobatics) check would resolve these situations, if the DM feels it necessary.

The second point is that ‘skill checks’ aren’t actually skill checks. Rather, they’re ability checks to which you can add your proficiency bonus if you are trained in the appropriate skill. Both ability and skill are at the discretion of the DM. For example, if the barbarian decides to bend a metal rod in front of a captive in order to frighten them, the DM might call for a Strength (Intimidation) check. Likewise, trying to swim a long distance might prompt the DM to ask for a Constitution (Athletics) check.

With these points made, we can move on to the main purpose of the article.

Perception vs. Investigation

These two skills are often confused or, worse, treated as Intelligence- and Wisdom-based counterparts of the same activity. Given what we covered earlier about checks being based on abilities, we can see that this idea is particularly likely to cause problems—and it does.

The difference between perception and investigation is the difference between using your senses and using your faculties. The examples provided on PH 178 are especially helpful in determining which skill applies based on what the players describe their characters doing. Most questions about the rules can be readily answered by referring to the books, but assuming that you’re reading this because you’re still unclear, we will endeavour to elaborate.

Investigation

“I never guess. It is a shocking habit—destructive to the logical faculty. What seems strange to you is only so because you do not follow my train of thought or observe the small facts upon which large inferences may depend.”

— Sherlock Holmes in The Sign of Four

This skill really doesn’t get the attention that it deserves, and that’s why we’re covering it first (and with somewhat greater detail). Many DMs use Perception when they should use Investigation, usually because they’re accustomed to asking for said checks in the context of measuring awareness to threats, and therefore it seems reasonable that the skill might apply to noticing finer details in their surroundings.

To understand when Investigation is an appropriate proficiency to apply, it may be helpful to consider an exemplar of the investigative arts: Sherlock Holmes. This fictional detective is shown on numerous occasions walking through a crime scene, observing countless minor details that others dismissed, and using that information to make deceptively straightforward deductions to general astonishment.

For example, the victim of a murder was left handed. How did he know? In the victim’s home, the ink pot on the left side of the writing space, their table knife with butter on the right side of the blade, their mug on the desk sitting with the handle to the left, and other clues all spoke to it. Without ever touching anything, Holmes uses Investigation to deduce details others overlooked. Though, of course, he can still get down and lift the rug, run fingers behind shelves, throw open drawers and rifle through their contents, et cetera, and still rely on Investigation—it’s a difference in method, not practice.

Adding to the confusion about this skill is that the official adventures also seem to forget that Investigation exists and substitutes Perception instead. For instance, in the starter adventure, Lost Mine of Phandelver, there are many instances (finding a waterproof satchel at the bottom of a well, finding an old chest in a partially collapsed cottage, finding a small wooden case in the ruins of an herbalist’s shop, and more) that should rightly be Investigation checks, but the adventure calls for Perception. And as many other adventures followed the precedents Phandelver set, this issue has continued to compound.

Perception

“‘What is the matter, Strider?’ Merry called up. ‘What are you looking for? Did you miss the East Wind?’
‘No indeed,’ he answered. ‘But I miss something. I have been in the country of Hollin in many seasons. No folk dwell here now, but many other creatures live here at all times, especially birds. Yet now all things but you are silent.’

J.R.R. Tolkien, The Lord of the Rings

Perception is the most commonly used skill in Fifth Edition. While travelling through the wilderness, stalking through a dungeon, or otherwise going about your life, Perception measures your awareness of your surroundings. It helps see candle light under a door, hear the footsteps of an invisible enemy, smell the rot of an approaching zombie, feel the subtle temperature drop as you pass deeper underground, and more. If a check relies on natural senses, you’re probably safe to assume that your proficiency in Perception applies.

We just finished talking about how the official adventures often call for Perception checks where Investigation is more appropriate, but there are many examples to be found where they get this right. Phandelver gets it right at least half the time, and so there are many excellent examples of Perception to be found. Listening through doors in the enemy hideouts, catching a whiff of strange odours, searching for hidden enemies, and keeping a lookout while travelling are all sensible and effective uses of the skill. These are cases of using your general awareness to notice something amiss.

Is there occasionally overlap with Investigation? Certainly, but such cases are really much less common than one might think. We encourage you to bear that in mind as you run or design dungeons, as it makes the game much less focused around one single skill—one that not every class gets proficiency with.

Passive Perception

It is also worth including a helpful note here about the game’s most frequently used passive score: your passive Perception. Passive scores are often misunderstood. For instance, a common question we see is “Can I roll lower than my passive Perception?” This is troublesome for several reasons, mostly because it is another example of players trying to use game mechanics—skills in particular—without being asked.

To clarify, passive scores are not a player tool, they are a DM tool. Passive Perception is intended for use in resolving hidden threats as an alternative to tipping the players that something might be amiss by calling for Wisdom (Perception) checks. As an accurate measure of someone’s average perspicacity, passive Perception is best used in practice to approximate a character’s general attentiveness, rather than their focused interest. If someone wants to pay attention for something specific, it is more appropriate to have them roll a Wisdom (Perception) check. And no, their passive score doesn’t factor in as a benchmark.

Putting It All Together

Investigation and Perception have similar objectives: to learn more about the world around them. The difference lies in the way that information is obtained. Investigation relies on observation and deduction and Perception relies on awareness and natural senses. This simple rule of thumb can help eliminate many disputes before they can begin.

Yet, even with this clarification, it’s silly to think that there will never be confusion about what skill(s) may apply to what situation. This is why the DM is singularly empowered to call for checks and to decide which ability and skill is relevant to the task at hand. Reminding your players of this fact, along with their responsibility to clearly explain what their character does, may go a long way to preventing such confusion from getting out of hand.

Have you had a notable experience with skills and ability checks? We’d love to hear from you in the comments below!


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