Pit Traps in Crypt of the Everflame

[seiken]

I am learning to GM, and am running some friends through Crypt of the Everflame so we can all get the hang of things before jumping into an Adventure Path.

The below contains spoilers, so don't read if you don't want to know what happens.

I got problems:

Last night, we reached the part early in the crypt (room 2) where there are pit traps throughout the room.

Type mechanical; Perception DC 15; Disable Device DC 20
Trigger location; Reset manual
Effect 10-ft.-deep pit (1d6 nonlethal falling damage); DC 20 Reflex avoids

Each trap takes up a full 5-ft. square.

The text says, "Probing for the pits with a pole or weapon grants a +4 circumstance bonus on the Reflex save to avoid falling into a pit."

I am trying to figure out how this probing works. I understand the trap as being set off when a PC stands on it; the weight of their body is enough for the floor to open and send them falling to the pillows. If that's the case, then I don't get how holding a pole or weapon helps you not fall.

If the +4 circumstance bonus is helping you detect the traps, then that seems like you are successfully detecting it from an adjacent square, meaning you wouldn't fall in anyway. And why would the trap even go off if you're just detecting it by probing?

I just don't get this at all, and would really appreciate if someone could help me understand how this is supposed to work.

Thanks!

[Thorkull]

Probing ahead with a pole doesn't mean you automatically detect the trap. So, basically, what it's saying is that if the players probe with a pole and don't succeed in the perception check, then give them a bonus on the save when they trigger it.

[Dabbler]

At a guess, imagine it like this:

Spoiler:

You have huge 5' square slabs around the room that will tip if the weight of a man goes on them. You can tip them with a tool like pole but only if you really push on it, pushing so hard with all your weight you might well topple into the pit as it suddenly shifts under the pole and you flip forward.

[Charlie Bell]

I think the idea is that the probing may or may not trigger the trap. If it doesn't trigger the trap, it may trigger when you're standing on it. The +4 to Reflex saves to avoid the trap is an abstraction of you triggering the trap by probing before you actually fall into it.

[seiken]

Thanks, everyone. Makes sense now :)