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View Full Version : Please Evaluate My Truth, Lies, and Sense Motive System



Defiant
2008-10-10, 09:20 AM
I have created a system for myself to help with the various Sense Motive rolls. Of course, I may not adhere to it rigidly because of flexibility in the responses and situation, and especially because of the sheer time involved. However, it does come in handy and to me makes a lot of sense. I would like your opinion on whether or not it sounds like a good idea.

When a person A bluffs,
The opposing person B makes a sense motive check.
If the check equals or exceeds the bluff check, then the opposing person B knows the truth about person's bluff (i.e. that she's lying).
If the check fails by less than 5, then the opposing person B cannot discern whether the person A is lying or not.
If the check fails by more than (or equal to) 5, then the opposing person B will come to a false conclusion.

When person A tells the truth,

Now, I have also instilled penalties on telling the truth, especially on sensitive information and when a person doesn't have reason to believe another. Two people will not necessarily always believe each other unequivocally if they're saying nothing but the truth.

The base Sense Motive DC for not reaching a false conclusion is 5. If your Sense Motive is lower than 5, then you will believe person A to be lying. This is balanced by the fact that within a level or two of fully improving Sense Motive, you'll stop having such a great chance of thinking a truthful person is lying.

However, person A also has to make a Charisma check. Person B's DC for not reaching a false conclusion is 5, but also 10 - (Charisma check if 5 or below). So if a person makes a horrible Charisma check in trying to tell the truth, they may seem incredibly nervous and lead the investigators to a false conclusion.



Of course, none of this is so extremely rigid. Not always do the failing people have to reach a false conclusion and not always is a Charisma check necessary (though in an investigation it will be). I may also adjust the numbers slightly (mainly in the "or equal to" sense).

This will also not burden the players too much, as I'm still rolling their Sense Motives. The only thing they might end up doing is a Charisma check here or there as requested by me.

So what do you think of this system? Too convoluted? Too unnecessary? The most brilliant thing you've ever heard? :smallwink:

AKA_Bait
2008-10-10, 09:47 AM
This should probably be in homebrew.

Also, at minimum, you need to take into account the middle ground here. A sense motive check is also something that comes into play when a PC or NPC is telling a half-truth or intentionally holding back information.

Defiant
2008-10-10, 02:38 PM
This should probably be in homebrew.

Also, at minimum, you need to take into account the middle ground here. A sense motive check is also something that comes into play when a PC or NPC is telling a half-truth or intentionally holding back information.

When someone is trying to tell a half-truth with the intent to deceive, that requires a bluff check.

A successful Sense Motive would reveal that the person is holding something back. A failed Sense Motive would reveal that the person is being honest and straightforward.

Devils_Advocate
2008-10-10, 08:18 PM
Well, I haven't done all the math, but at a glance, it looks like it could be easier for someone with a very high Bluff score to convincingly lie than to convincingly tell the truth. That's something I'd want to avoid; for precisely that reason, I'd rename Bluff to Convince or something and make it the skill to use to convince people of factual claims, be they true or false. Also, it might be best to make things even more continuous than (believes you -- not sure -- disbelieves you). E.g. "I'm pretty sure he's telling the truth." That seems more realistic. So, basically, I'd want to wind up using some variation on the formula

Degree of Belief = ([Bluff/Convince Check] + [truth of statement]*([Sense Motive Check]+C) + [circumstance modifiers])/20

where C is a constant. The circumstance modifiers cover the statement's a priori plausibility, the speaker's apparent trustworthiness, etc. The [truth of statement] ranges from 1 for true to -1 for false, with intermediate values for things in between: kinda true, technically true but misleading, don't really know for sure, etc. Obviously, what it actually covers is what the speaker believes, not whether his claim is true in reality.

The trick is finding the right value of C. Obviously, C + [lowest possible Sense Motive Check] needs to be at least zero if you want to avoid people believing things because they're lies, or disbelieving because the speaker is being honest.

EDIT: Hmmm... Actually, instead of just whether someone believes a statement to be factually true, this should really measure the degree to which someone believes whatever ideas about the speaker's intentions that speaker is trying to convince them of; you might try to trick someone into thinking you're lying or holding something back when you really aren't, for example. So replace [truth of statement] with [sincerity], I think.

Then it seems like it should cover a lot. Like the misinterpretation of sarcasm, for example.