D&D 5E Use of Investigation

[sunrisekid]

I've been having the party rogue use Perception to find traps, Investigation to disable them.

 

[Minigiant]

I don't agree with this exactly. How much activity and physically messing around with things do you assume with an investigation check and where does it stop? Suppose there was a key stuck to the bottom of a desk with a blob of wax? Would you assume that an investigation check meant that the PC upended the desk and found the key?

To further complicate things suppose you DO assume that, and the desk is trapped. If moved, a large block falls from the ceiling doing nasty damage to anyone underneath it. If you assume the check moves the desk and the trap triggers then the player might say " I never said I touched/moved the desk!"

For this reason I prefer to let the player tell me exactly what they are doing first, then determine the chances for any roll( if required at all) based on that info then assume actions and assign static DCs.

Well the DM shouldn't control the PCs. The DM would tell the player with a high enough roll that "Something important is probably in the drawer."

Investigation rolls give you sensible hints and logical steps. The whole point is that you don't have to search and poke everything. You roll it and the PC knows the best places to poke and search and the DM tells you what the PC should know.

Player: I search using Investigation. I rolled a 21 for Investigation.
DM: You know that things commonly fall under table and get stuck on goo or fall between cracks. Especially in a room this messy.
Player: I check under the table.
DM: You check under the table, slide it a bit and notice a weird scratching. Something is under the table leg.
Player: I flip the table.
DM: You flip the table and find a key stuck to the leg's bottom.

 

[ExploderWizard]

Intelligence (Investigation) is for Active search for things you don't know are there or can't perceive without interaction.
Wisdom (Perception) is for Passive Search and for Active Search of things you can already perceive.

Basically
Perception is for searching in plain sight.
Investigation is for search in hidden view.

Like the PHB say, you can't find a key in a drawer with Perception unless you say "I open the drawer" to open the drawer.
But you can find the key with Investigation because rolling high enough "makes you open the drawer".

Also Investigation is the "logical step search".
Perception tells you that the noble's shoes are dirty.
Investigation tells you (if pointed out via Perception or interaction) that the dirt is fresh, what type of dirt it is, and that noble is a dirty liar and he did go outside during the ball..... ARREST THAT MAN AND HOLD HIM FOR FURTHER QUESTIONING!!!.

Well the DM shouldn't control the PCs. The DM would tell the player with a high enough roll that "Something important is probably in the drawer."

Investigation rolls give you sensible hints and logical steps. The whole point is that you don't have to search and poke everything. You roll it and the PC knows the best places to poke and search and the DM tells you what the PC should know.

Player: I search using Investigation. I rolled a 21 for Investigation.
DM: You know that things commonly fall under table and get stuck on goo or fall between cracks. Especially in a room this messy.
Player: I check under the table.
DM: You check under the table, slide it a bit and notice a weird scratching. Something is under the table leg.
Player: I flip the table.
DM: You flip the table and find a key stuck to the leg's bottom.

So you would assume the player just set off the trap by rolling an investigation check? I would be fine with that in your example because the DM didn't ask for a check, the player just announced he was rolling it.

 

[iserith]

For this reason I prefer to let the player tell me exactly what they are doing first, then determine the chances for any roll( if required at all) based on that info then assume actions and assign static DCs.

That's what I do and it works great. It's fine if the players say "I search the whole room, top to bottom..." or "I toss this place exhaustively..." without getting into specifics. I can then decide whether there's a check or not plus an expenditure of time. Time is usually an important consideration in my adventures.

As far as traps go, I will have already telegraphed some clue related to the trap in the initial description of the environment. If the players don't think to investigate it, oh well. That I included a clue in the initial description removes any concern that it will be perceived as a "gotcha."

 

[iserith]

Player: I search using Investigation. I rolled a 21 for Investigation.

At my table, I would respond with:

"Please tell me your goal and approach and I'll tell you if you need to roll or not."

Players don't ask to make checks or "use skills" at my table. They describe what they want to do and then I tell them the result, sometimes asking for a check if I think their goal and approach relative to the situation has an uncertain outcome. In a game where the DM decides on success, failure, or uncertainty, players shouldn't really want to roll if you think about it. They should just want outright success and roll only when necessary.

 

[Minigiant]

At my table, I would respond with:

"Please tell me your goal and approach and I'll tell you if you need to roll or not."

Players don't ask to make checks or "use skills" at my table. They describe what they want to do and then I tell them the result, sometimes asking for a check if I think their goal and approach relative to the situation has an uncertain outcome. In a game where the DM decides on success, failure, or uncertainty, players shouldn't really want to roll if you think about it. They should just want outright success and roll only when necessary.

To me, Investigation is a knowledge skill. It's more "Tell me what my character knows and infers based on the information he has." So the DM tells you where to search. You might not find anything due Perception, but you know where to search.

Investigation: Where do I search? What does the things I've found mean?
Perception: What do I see? What do I hear? Is there anything hidden in my plain view?

 

[iserith]

To me, Investigation is a knowledge skill. It's more "Tell me what my character knows and infers based on the information he has." So the DM tells you where to search. You might not find anything due Perception, but you know where to search.

Investigation: Where do I search? What does the things I've found mean?
Perception: What do I see? What do I hear? Is there anything hidden in my plain view?

For me, Investigation is all about deducing a clue in hand, when that deduction has an uncertain outcome. Searching around for something hidden, when that effort has an uncertain outcome, is Perception.

 

[Minigiant]

So you would assume the player just set off the trap by rolling an investigation check? I would be fine with that in your example because the DM didn't ask for a check, the player just announced he was rolling it.

Yes.

If the player says they use the skill to search, they spring the trap.
If the DM ask for a roll to ideas where to search, they just know that the area is a good place to search.

For me, Investigation is all about deducing a clue in hand, when that deduction has an uncertain outcome. Searching around for something hidden, when that effort has an uncertain outcome, is Perception.

Searching around for something hidden that you can see, hear, smell, feel, or taste is Perception.
Searching around for something you must guess for its location is Investigation.

If you are searching for something using your senses, it's Perception. "I see a foot behind the crate."
If you are searching based on your knowledge and logic, it's Investigation. "The only thing large enough to hide anything major in here is that crate."

 

[Rya.Reisender]

I don't have any problems with differentiating the two. The result of both can be the same but the way a PC wants to find something pretty exactly determines which of the two is used.

Perception is just outright searching. You look around without a plan and notice it.
Investigation on the other hand is rather understanding mechanisms and deducing the location from that.

 

[mpwylie]

I don't agree with this exactly. How much activity and physically messing around with things do you assume with an investigation check and where does it stop? Suppose there was a key stuck to the bottom of a desk with a blob of wax? Would you assume that an investigation check meant that the PC upended the desk and found the key?

To further complicate things suppose you DO assume that, and the desk is trapped. If moved, a large block falls from the ceiling doing nasty damage to anyone underneath it. If you assume the check moves the desk and the trap triggers then the player might say " I never said I touched/moved the desk!"

For this reason I prefer to let the player tell me exactly what they are doing first, then determine the chances for any roll( if required at all) based on that info then assume actions and assign static DCs.

I use investigation much like Minigiant. Let's say the players perceive a small desk in the room then they say they want to search the desk. Let's say in the situation above there is a key stuck to the bottom of a drawer. I don't want to take 15 minutes on every desk or dresser in the game for the players to say "I search the dresser", then "I pull out each drawer and check the bottoms", then "I search in the opening where the drawer was", etc. I generally set up a staged DC. So the player says "I search the desk". If finding the key is required to proceed and then they will find the key no matter what but the roll determines whether there are repercussions. maybe <10 they find it but it makes noise and they draws nearby monsters. a 10-20 they find it but it takes time which affects the timeline, maybe the monsters they are chasing get further away or catch up some, have more time to prepare for them, etc. a >20 they find it right away with no negative repercussions.

I also use investigation if they are looking for info and are asking around town or reading a tome for clues. They roll low they find just enough info to proceed, they roll medium they get more info, if they roll high they get all the info in great detail. An example of this just happened in my last session. The PCs were looking for a hidden fortress of a long dead mage. They had heard there there may be some info in the library of a nearby city so they went there to try to get more info. I had them make an investigation roll at the library and they found a tome with the info they needed. The result of the check determined the info they received. A low roll they would have gotten a general clue to a large area it could have been in and it would have taken a lot of time for them to actually find it, that time would have given the bad guys time to progress their agenda. A medium roll they would have gotten more specific info so they could find it quickly with no time repercussions, and a high roll(which they got) not only gave them a detailed location but also gave them details of what they would find when they got there.

Every situation is different but I prefer to set up varying degrees of success as to me it makes the rolls more meaningful then pass or fail and makes the PCs skill selections more meaningful.