Observations and Interactions in 5E

[Nickademus]

I made this for my players, but I wanted to share it here as well in case it might help anyone.

Observations and Interactions

The purpose of this article is to provide in greater detail the ways in which a character in a 5E game interacts with the environment, including several topics that aren’t fully explained in the PHB. The contents of this article comes from a mix of information presented in the PHB, DMG, Xanathar’s, Sage Advice article and the Sage Advice podcast sections. A few of my own house rules are included, and noted as such to keep them separate from what could be considered official rules.

Active Skill Use

The main way of observing and interacting with the environment is through the use of ability checks, usually with a bonus from proficiency with a skill or set of tools. There are two methods of using ability checks, actively using an ability check and relying on a passive check.

When you actively use a skill or tool, you tell the DM that you want to make a check to attempt to gain some information about the thing you are observing. There are several skills and tools that can be used for observations, but mostly a character uses the Investigation, Perception, Arcana, and Insight skills.

Investigation
The Investigation skill is based on Intelligence and is used to search an object or area for something in particular. When you investigate, you have an idea of what you are looking for and use your knowledge of what you should expect to find to aid in your search, hence why the skill is an Intelligence check. Some examples of active Investigation checks are searching a chest for a false bottom, searching a bookshelf for a specific title, and searching a lock for a trap.

Touching Things
It is assumed that you touch any object or area you are actively searching. This is because the Investigation skill assumes a thorough examination is being done. In some cases, this touching can cause other things to happen, such as curses, and magical traps.

To examine an object or area without touching, you need to state that you wish to ‘Investigate without touching’. Doing so might increase the DC to find what you are looking for or impose disadvantage on the roll, though more than likely you simply will be unable to find certain information without touching. For instance, an expensive painting is mounted on a wall. The frame has a trip wire around the frame that triggers a trap if the painting is removed. The wire isn’t visible as it sits between the frame and the wall. A normal Investigation to search for traps grants the opportunity for the character to feel along the frame and notice the wire, whereas an Investigation without touching would not discover this information no matter how high the roll.

Perception
The Perception skill is based on Wisdom and is used to rely on instinct and intuition to get a feeling when something perceived through one or more of the character’s five senses seems important or out of place. This skill is used when you don’t know exactly what you are looking for but just want to notice anything worth noticing. Some examples of active Perception checks are searching a wall for anything out of the ordinary (traps, a secret door, secret compartments, etc.), scanning a crowd to notice any threats, and searching a body for anything of interest.

There is a fine line between what is investigation and what is perception. They both cover largely the same actions. It is the method and intent that differs, and thus the important distinction is if the character is knows specifically what they are looking for.

Secret Doors and Traps
A good example of the difference, and the symbiosis, of these skills is the act of searching for traps, secret doors, or secret compartments. For example, a character comes to a corridor leading to a door. Feeling the corridor is suspicious, the character decides to search for traps. Since the character doesn’t know if the potential trap is a pit trap, dart trap, scything blade trap, collapsing ceiling, or so on, the character makes a Perception check to just look around for anything out of place. (The character rolls poorly and find nothing.)

Feeling the corridor is safe, the character heads down to the door. Upon seeing the door is locked, the character gets suspicious again and decides to search the lock for traps. Since the character knows what it is looking for, any parts in the lock that have nothing to do with the keyhole and tumblers, the character makes an Investigation check. (The character rolls high and notices the poison needle trap.)

After triggering the poison needle with a dagger and picking the lock with tools, the character opens to door to find nothing but a stone wall beyond; the door was a fake. There must be another way to progress, so the character searches the wall again, specifically for a secret door. This time, since the character knows what it is looking for, it makes an Investigation check. (Rolling better, the character notices the outline of a door in the wall.)

Now knowing there is a secret door, it is a matter of finding the means to open the door. This could go two ways. If the character chooses to just search the wall for anything that might cause a reaction, a Perception check would be made. If the character specifically states that it is searching the wall for a spot that could be pushed like a button, an Investigation check would be made. The main difference is that Investigation DC’s tend to be lower, but if the secret door is opened by a different means, the Investigation check might not find it. So there are pros and cons to both relying on Perception and using Investigation.

Touching Things
As with Investigation, it is assumed that you touch any object or area you are actively searching. This is because the Perception skill involves all five senses and the tactile sense (sense of touch) is one of the ways you can perceive something. Again, this touching can cause other things to happen, such as curses, and magical traps.

Just as with Investigation, you can examine an object or area without touching anything by stating that you wish to ‘Perception without touching’ (ignoring the bad grammar). This may prevent you from noticing certain things, especially if the information is based on temperature or texture.

Opening Things
Even though you are assumed to be touching things in the area you are searching, it is not assumed that you interact with any objects, such as furniture, while searching unless you state that you are. For instance when you search a chest, it is not assumed that you open the chest and search the inside for wire or hidden compartments. In fact, determining if it is safe to open the chest may be precisely why you are searching in the first place.

Thus, to include the interiors of objects or places that aren’t immediately accessible in your search, you must state you are opening any impediments that block you. For example, a character wants to search a jail cell block for clues. Since the doors are all closed, the character must state that it is using the jailor’s keys to open each cell while conducting the search.

Arcana
While not used as much as Perception or Investigation, the Arcana skill is also used to observe the environment. The Arcana skill is based on Intelligence and uses knowledge of arcane topics, such as magical energies, planes of existence, and advanced mathematics, to gain a better understanding of something you are interacting with.

Magic in 5E isn’t a hidden thing; it is usually quite noticeable, from glowing runes, to a tingle in the air, to a sense of dread. There are many things, tangible and intangible, that accompany magic and can be used to get an understanding (or at least a hint) of what to expect from the magic.

One of the uses of the Arcana skill that isn’t well know is that it is used to find and disarm magical traps. You don’t use tools for these kinds of traps. Now some magical traps might still use Perception or Investigation to notice, but many of the magical traps have some sort of emanation of energy or effect on the nearby environment that someone not knowledgeable about arcana wouldn’t think of as important. This allows a character to make an Arcana check to identify strange feelings or occurrences as indications of a magical trap.

The Arcana skill is also used to directly disable most magical trap, in addition to the dispel magic spell, though the specifics of how this generically works aren’t detailed in the rules. The idea is that each magical trap might be designed with a way to short circuit and diffuse the magic energies by taking some action combined with an Arcana check. Some DM’s may wish to detail this for each trap, while others may wish to simply leave it as ‘you make a check and the magical trap ceases to function’.

** House Rule: Arcana Proficiency **
In my games, I find the Arcana skill to cover a large amount of technical information that it is unreasonable to assume that anyone could have come across in their lifetime. Thus for any Arcana check dealing with a subject more complicated than simple mathematics, proficiency in the Arcana skill is required to be able to make the Intelligence (Arcana) check. This applies for magical traps as well: only those with proficiency in the Arcana skill have the in-depth understanding of how magical auras work to figure out how to disrupt them.

[Nickademus]

Insight
While not used in the same way as the trio of Perception, Investigation, and Arcana, the Insight skill can make it easier to get a proper feel of a person being interacted with. When a player is not sure if an NPC is speaking and/or acting truthfully, the character can make a Wisdom check (with proficiency if proficient in Insight) to get some feedback from body language, mannerisms, and appearance.

Passive Skills

The second method of using ability checks involves assuming that checks are being made, without the need for rolling. This has two effects, and it is easy for a DM to forget or overlook this part of the game.

The first effect that a passive skill has is that it is always on. This means that as a character is walking around, it is constantly using passive Perception, Investigation, and Arcana. This complicates the DM’s job, but to deny a character its passives is to remove a major source of interaction from the game, especially if the character has invested in increasing their passive perception scores.

The second effect that a passive skill has actually helps to make it easier on the DM. This is because a characters passive score for a skill is the lowest possible result for ability check. This means that if a character makes an active Perception check and rolls lower than its passive Perception score, the passive value is used instead. That means that if a character’s passive is high enough to observe something, no roll is needed, reducing the number of rolls in the game and speeding things up a bit. In fact, a character’s passive skills such inform them of information about their environment before they even have time to ask to make a roll.

Limitations
Passive skills have several limitations that keep them from overshadowing active skill checks. The following should be considered both when determining what a characters passive score is for a specific check and when determining if the passive is even applicable.

Not Touching Things
It is assumed that you do NOT touch any object or area when passively scanning. Passive checks are based on your senses functioning while you are simply walking around or doing other activities. (If you were actively searching then you would be actively making skill checks.) Thus it is unrealistic to think that a character is fondling every object, wall, floor, and ceiling they come across as they go about their day.

This means that there may be information that passive checks fail to reveal, the same as active checks that choose not to touch things. If you find yourself in a position where it is beneficial to be extremely thorough while you transverse an area, you can state that you wish to ‘Touch everything while exploring.’ This will provide more information from your passive checks, but will also automatically trigger anything that responds to touch in the entire area you are exploring.

Also note that passive checks, even while touching everything, still don’t open objects.

Range and Obstructions
Passive checks are usually made at a distance. Technically, the first check is made as soon as the character can possibly observe the information of the check. Though it is important to remember that this is still limited. You aren’t assumed to move around from your location to observe things, so obstructions can prevent you from knowing about certain things. For example, if someone placed a gold coin under a vase, no matter how high your character’s passive Perception score, your character will not see the gold coin unless the vase is picked up.

Also many observations have a maximum distance, meaning that if your character is beyond that distance, you passive checks won’t give you the information until you get closer. For instance, a character’s passive Perception checks can reveal the outline of a secret door, but many secret doors have a maximum range of as little as 10 feet. Thus, no matter how high your character’s passive Perception score, until you walk within 10 feet of the wall, you won’t realize there is a secret door on it.

In other words, if your character has high passive scores, don’t expect to walk in the door to a room, glance around, and know everything about the room.

Vantage
Another aspect of the rules that has a major effect on passive scores used for observations and interactions is the mechanic of advantage and disadvantage. If a skill check receives advantage, the passive score for that skill is increased by 5. Likewise, if a skill check receives disadvantage, the passive score for that skill is decreased by 5.
This can be important when the situation imposes disadvantage on your ability to notice things. For instance, darkvision allows a creature to see in darkness as if it were dim light, but dim light imposes disadvantage on Perception checks. Therefore the creature’s passive Perception score is 5 less when using its darkvision.

Passive Perception
This passive score is the most used of all the passives. It represents your ability to notice things without trying. It is the most helpful for finding things that people want to hide (traps, secret doors, secret compartments, etc.). It is also the passive that many DM’s mistakenly use exclusively for everything, assuming they remember to use it at all.

To understand if something can be spotted with passive Perception, ask yourself this: is the thing hidden in a way that makes it hard to notice or is it in plain view? If it is hidden, then passive Perception notices it.

Passive Investigation
Despite being called Investigation, this passive has little to do with the idea of actively investigating. It is more like a ‘passive understanding’ check. This is because the passive Investigation score tells whether your knowledge of the way things should be doesn’t match what you are sensing. For example, your character walks into a tavern and sees the various patrons, one of which is a tattooed man wearing laborer’s clothing. A high passive Investigation could allow you to realize that the man bears a specific tattoo that makes him a member of a local thieves’ guild and that he probably isn’t a laborer at all. The tattoo isn’t hidden, so passive Perception isn’t needed. But if your character isn’t very smart, they might not make the connection between the tattoo and the local thieves guild.

To understand if something can be spotted with passive Investigation, ask yourself this: is the thing hidden in a way that makes it hard to notice or is it in plain view but the characters might not understand the significance of it? If it is in plain view, then passive Investigation allows a character to realize that what they are seeing is important for a specific reason.

Passive Arcana
This passive isn’t directly listed and is almost never used. But the idea remains that if a character can automatically sense magical energies, they can pull on their knowledge to tell what those energies are. In a lot of ways, this passive is similar to passive Investigation, only focused on the specific knowledge that the Arcana skill provides.

This is also a way for character to notice magical traps in the same way that passive Perception notices mechanical traps.

Passive Insight
This isn’t really a passive, but it probably should. The idea behind the Insight skill is that your character gets a feeling about an NPC. This should be automatic without the character having to stop and think ‘do I trust this person?’

Executing the Insight skill as a passive score check rather than a rolled skill check also helps to preserve the flow of roleplaying while interacting with an NPC instead of breaking the immersion by handling a die roll in mid-conversation.

[Nickademus]

Stealth and Invisibility

Another aspect of observations and interaction deals with the ability to see and locate the thing being interacted with.

Stealth
Under certain circumstances, a character can take the Hide action (note that this action is not always available). When the action is taken, the character makes a Dexterity (Stealth) check, usually where only the DM can see. From that point on, the character may be hidden. The character’s Stealth roll is then compared to the passive Perception scores of NPCs (or active Perception check of NPCs specifically looking for the character).

It is important to note that your status of being hidden is specific to each creature that has the chance to notice you. This means that even if you are ‘discovered’ by one creature, unless it notifies other creatures, you are still hidden from the others until they notice you on their own. (The wording in the PHB seems to indicate that you stop hiding the first time anything notices you, which isn’t exactly how things work.)

Invisibility
This effect tends to cause confusion in how it fits in with the idea of observations. Many people seem to think that a creature that is invisible cannot be noticed. This is not true. A creature notices thing through the use of the Perception skill, which incorporates all five senses (if the creature has them), not just sight. The invisibility spell does nothing to silence a character or suppress their smell, for instance.

This means that a character that is invisible can still be noticed and located, without the need for any check. Everyone knows the square an invisible creature is in and can attack it if desired.

What invisibility does do is allow the character to take the Hide action at any point. Hiding involves masking yourself from all the senses, so that an invisible, hiding character can easily sneak around. The difference is that if you don’t take the Hide action, enemies know you’re there; they just suffer disadvantage to attack you.

It should also be noted, though, that being invisible keeps you from being targeted by many spells and abilities, as well as opportunity attacks. Thus being invisible even without hiding can still be a benefit.

Magic Items

Magic in 5E isn’t subtle. While there are variants to change things, by default, magic can be felt; it has a presence. Merely holding a magic item gives a character the knowledge that the item is magical. No check is needed.

Identification
In an attempt to remove the perceived requirements of certain classes to the adventuring party, aspects such as magic item identification has been made easier in 5E. Any character may spend a short rest examining and holding a magic item to figure out what it does. No check is required.

Magic Auras
Every form of magic has an aura. Some can be openly felt, most are invisible unless a character casts the detect magic spell. Figuring out the type of aura (conjuration, for example) can be done a couple ways. The detect magic spell instantly tells you what type of auras are present on a creature, object, or place; no check is required. Some DMs will also allow an Intelligence (Arcana) check (or passive Arcana) to determine the type of a noticeable aura, without needing to cast detect magic.

Appraising Items

While most nonmagical items have a set value, it isn’t always apparent what it is. This is especially true with gems, jewelry and art objects.

Gems and Jewelry
The expanded tool rules in Xanathar’s Guide to Everything provides a way for characters to determine the value of gems (and thus jewelry) without just automatically giving the characters knowledge of the value. A character that has proficiency in jeweler’s tools can appraise gems at a glance. This would imply that characters without the tool proficiency might be able to appraise them with a regular Intelligence check.

** House Rule: Appraising Other Items **
Following this example, in my games the PCs can appraise art objects and other items of value with an Intelligence check. A character that is proficient in the tools used to make the item can automatically appraise the item at a glance. This puts some more game value on the tool proficiencies and can offer a compromise between good game pacing and roleplaying item appraisal.

[Thegroo]

Good post.
Thank you

[Zacchaeus]

Stickied

[LordEntrails]

Very nice, I do like the ideas of tool proficiency giving you automatic appraisal.

I do have a couple of comments, my understanding of a couple things is a bit different than what you detail. Specifically;- Perception (active and passive) to me doesn't tell you what is hidden, rather it tells you something that is out of place or unusual. Such as, rather than detecting a secret door, trapped floor etc, I would tell the players something like; "you notice that their seems to be a draft coming from the wal on your left." Or, "The wall on your left is made of a lighter colored stone." Or, "The section of floor ahead of you appears to be slightly concave." Or "You see a thin black wire stretched across the hall ahead of you." Or, something else that tells the players something is amiss, but not what it is (that requires Investigation, imo).


I've never heard mention of any skills being passive except for perception. Do you remember where that concept is from?


Your example of passive investigation (tattoo on the guy in the bar) seems more like a passive Insight check to me. But, I can see how passive investigation might work.

[Zacchaeus]

I've never heard mention of any skills being passive except for perception. Do you remember where that concept is from?

Page 175 of the PHB. Whilst it examples Perception in the text it is clear that any skill can be used passively. (Although I'm not sure how you would use athletics passively )

[Axoid]

Thank you, I shared this with my players.

[damned]

Page 175 of the PHB. Whilst it examples Perception in the text it is clear that any skill can be used passively. (Although I'm not sure how you would use athletics passively )

You know when you are walking along the footpath and you trip over that crack that is about 3mm high.
Thats failing your passive athletics check.
When you break your hip as a result that is just because your old.

Of course - it could be because you were out drinking all night and you failed your constitution check...

[Nickademus]

Very nice, I do like the ideas of tool proficiency giving you automatic appraisal.

I do have a couple of comments, my understanding of a couple things is a bit different than what you detail. Specifically;- Perception (active and passive) to me doesn't tell you what is hidden, rather it tells you something that is out of place or unusual. Such as, rather than detecting a secret door, trapped floor etc, I would tell the players something like; "you notice that their seems to be a draft coming from the wal on your left." Or, "The wall on your left is made of a lighter colored stone." Or, "The section of floor ahead of you appears to be slightly concave." Or "You see a thin black wire stretched across the hall ahead of you." Or, something else that tells the players something is amiss, but not what it is (that requires Investigation, imo).


I've never heard mention of any skills being passive except for perception. Do you remember where that concept is from?


Your example of passive investigation (tattoo on the guy in the bar) seems more like a passive Insight check to me. But, I can see how passive investigation might work.

The Observant feat grants a +5 bonus to passive Investigation.

Insight is based more on interaction than just observing. The passive Investigation for the tattoo is based on your knowledge of the tattoo rather than anything the guy is doing (hence Intelligence instead of Wisdom).