D&D 5E Perception vs Investigation

[DEFCON 1]

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.

 

[Quickleaf]

[MENTION=54629]pukunui[/MENTION] I'd say that adventure writers mostly only write situations that call for Perception. Then they take some of those situations (mostly finding trips) and require Investigation instead. Probably this is because D&D adventures have historically been about dungeon exploration and less about mysteries & intrigues.

What investigation does is well spelled out: clues gained thru deduction and discernment. While Perception checks only require the writer to place a game element, Investigation checks require the writer to devise a logical composition and connection of that element to others.

For example, the PCs are at a gambling den in the Thieves' Quarter.

Perception checks can be used to see if they can spot hidden weapons or hidden cards on players, the subtle use of magic to cheat, or that strange black-purple gems are discretely used at the high-stakes tables.

Investigation will reveal that silver coins are conspicuously absent from the gambling tables (suggesting some of the patrons have aversion to silver...like werewolves or devils), that certain players are winning much more frequently than others, and that the eerie purple-black gems appear to have varying values in the games ranging from a couple hundred to to a couple thousand gold (that their physical appearance does not suggest - they're soul gems).

 

[TrainedMunkey]

I first became confused when I saw a reference to a passive investigation check to find a secret door.

While passive perception is used for surprise round etc.

I believe that they can be fairly interchangeable, but at my table I use Investigation to spot clues to something, mainly looking for secret doors, and Perception to notice natural surroundings, enemies etc., surprise round mainly. If a player can convince me to use Investigation for surprise round, I would let her. As stated above they seem to be opposite sides of a coin, i.e. an int and wis version of very similar skills.

The more I run my group through HotDQ and RoT, the more it becomes obvious that Kobold was not working with a complete understanding of the rules and that they some what in the dark.

 

[aramis erak]

It's a little clearer in the DMG, but I agree - the definitions in the PHB are really, really bad.

Perception allows you to notice something is wrong.
Investigation allows you to determine what is wrong.

In the case of traps, Perception allows you to notice that there's something wrong about the area - less travelled, strange holes, that sort of thing.
Investigation allows you to discover a pit trap or a flame jet or whatever, with a little searching.

In this case, you can only attempt a disarm check if you've succeeded at an Investigation check first.

However, that may not be what's intended.

I'm very tempted to instead of putting in an Investigation or Perception DC to instead have a "Detect DC" and let individual DMs work out what skill applies. I'd appreciate any thoughts on this!

Cheers!

I tend to agree about detect DC.

I think the difference between the two is more along the lines of...
... Perception is to notice that which you aren't expecting/looking for.
... Investigation is to notice what you're looking for (or trying to avoid), or that something is the wrong size/shape.

The false box bottom is investigation. Noticing that the guy's face isn't right is perception; noticing that it's a good mask, glued on, is an investigation.


I think the avoidance of dual checks, especially one to spot and one to investigate, is to avoid "roll until you fail" situations.

 

[MARCVS AVRELIVS]

This has been a very helpful thread.

But now I'm unclear on the roll of Tool Proficiency (thieve's tools) ... is that just used to pick locks?

 

[iserith]

This has been a very helpful thread.

But now I'm unclear on the roll of Tool Proficiency (thieve's tools) ... is that just used to pick locks?

Proficiency: Thieves' Tools (usually tied to Dexterity) is used for disarming traps or picking locks, when the outcome of those actions is uncertain in the DM's estimation.

The use of an Intelligence (Investigation) check with regard to traps is suggested when figuring out how the trap works is uncertain. Before that is resolved, it may be simply impossible for a rogue to disarm a trap (no roll - automatic failure).

 

[SkidAce]

This is getting complicated...perception to notice, investigations to figure it out, tools to disarm....

 

[MerricB]

Here's Jeremy Crawford's tweeted reply to my query on Perception vs Investigation:

"Rule of thumb: Use Perception to spot/hear something. Use Investigation to deduce something based on clues. There can be overlap."

Cheers!

 

[pukunui]

Yeah, I tweeted Crawford as well.

I said: "So far use of Perception vs Investigation has been inconsistent in 5e modules. We need a Sage Advice column to clear it up. EG: In LMoP, secret doors are found with Perception. In PotA, they're found with Investigation."

He replied: "The default, as stated in the Player's Handbook, is to use Perception to spot a secret door."

So I've said: "Why does PotA use Investigation then?"

 

[Fralex]

This is getting complicated...perception to notice, investigations to figure it out, tools to disarm....

Sometimes I just want to run down a dungeon hallway with my eyes closed and my ears plugged, just to make things simpler.