Suppose you're trying to read someone's motives from their expression and mannerisms, or guess what they're thinking. Which skill is that? Perception?

Discipline is the one you use to see through lies, I know, but what if the person isn't trying to deceive you? In other words, which skill is used for general social perceptiveness?

Discipline doesn't let you see through lies--at least not to find the truth. It does prevent you from being moved towards the result the liar is going for. If a liar isn't trying to get you to do something, then Discipline isn't any real help.

The rule book says deception is opposed by discipline which seems a bit odd to me. I would have expected either perception or streetwise.

Vigilance would be a good choice, to notice odd behaviour,

For body language I'd use Perception.

Discipline is what you are looking for , however there is super vigilant talent called unrelenting skeptic. This allows you to add ranks of vigilance as failure to your opponents check, however if someone is trying to decieve you it is an opposed check with their deception against the PCs discipline. This is essentially using your own mental resilience to not be fooled by their fast talking or being disciplined enough to pick up on their mistakes and flaws in logic.

Perception is used to notice things which are currently there in front of you, so example someone is using a guard uniform that is 2 sizes to big for them , so you can then figure out that the uniform is stolen, or that the person is 1.5 m tall and combined with an appropriate knowledge check that said guardsman have a min height limit of 1.4m

This will also depend on what you're dealing with and in what context. The various knowledge skills (Xenology, Core Worlds, and Outer Rim primarily; the other ones to a lesser degree) might be relevant if you're dealing with unusual physiology or culturally-dependent cues, and a case could be made for other skills in specific situations (Streetwise with shady sorts being an obvious example).

When you say "read" someone, are you talking about the "reading" that Joe Navarro talks about in his book "What Ever Body is Saying?"

That kind of "reading" is not modeled in the Star Wars RPG's. At all.

I honestly don't think it's modeled in any RPG.

If you were to try to model that level of "reading," I'd recommend Perception.

In the rules deception is opposed by discipline and that reflects not whether or not you are deceived, but whether or not you act on the information presented.

I think what they mean by read is what type of person are they. Are they trustworthy, are they shifty and dishonest, are they brave or likely to bolt at the first sign of trouble. This would be down to various opposed social checks since these are used to pick up on the things like micro expressions or tells when someone is being trustworthy or lying. Perception is more about seeing things that are already there , vigilance is more about being prepared for something or reacting to something that is about to happen now.

I use Vigilance at my table or sometimes perception.

In the past, I've considered creating a "Sense Motive" custom skill. If I ever decided to go that direction I would just make it a career skill for every career.

4 hours ago, syrath said:

I think what they mean by read is what type of person are they. Are they trustworthy, are they shifty and dishonest, are they brave or likely to bolt at the first sign of trouble. This would be down to various opposed social checks since these are used to pick up on the things like micro expressions or tells when someone is being trustworthy or lying. Perception is more about seeing things that are already there , vigilance is more about being prepared for something or reacting to something that is about to happen now.

Really, what I have in mind is a variety of social perceptiveness tasks: estimating someone's personality traits from their mannerisms (like you say), discerning their mood from their behavior without having to ask, guessing at what their goals might be when they haven't told you.

14 hours ago, HappyDaze said:

Discipline doesn't let you see through lies--at least not to find the truth. It does prevent you from being moved towards the result the liar is going for. If a liar isn't trying to get you to do something, then Discipline isn't any real help.

Interesting. Which skill would you use to notice lies that aren't trying to get you to do something?

The situation could vary based on the lie being told. For example if some NPC is laying out a line of BS in relation to some sort of fact or issue, a PC with ranks in an appropriate Knowledge skill could make an argument they are well versed in the topic and want to use that to spot the deception.

15 hours ago, DaverWattra said:

Suppose you're trying to read someone's motives from their expression and mannerisms, or guess what they're thinking. Which skill is that? Perception?

Discipline is the one you use to see through lies, I know, but what if the person isn't trying to deceive you? In other words, which skill is used for general social perceptiveness?

Reading someone's motives isn't really an option in this game unless you have the Sense Thoughts upgrade to the Sense power.

If you want to pick up on visual or audio queues that the NPC could be displaying, that could be Perception/Vigilance/Cool but it isn't really going to give you any insight past "they are doing this thing with their voice/with their body as they talk". Further context is needed for the PC to really get some idea that something is off. Social encounters should very much be more than one dice roll, especially if you are questioning someone or trying to get information from them.

Discipline is really for whether you are deceived or not but it doesn't give you any insight past "you believe/don't believe this person". For that, I'd suggest you begin asking more about whatever they are speaking about to get more information/context and go from there.

The GM could very well call for Perception/Vigilance or even Cool checks to spot oddities that the PC can then use the knowledge of to further the discussion.

44 minutes ago, DaverWattra said:

Interesting. Which skill would you use to notice lies that aren't trying to get you to do something?

It may seem like a cop out, but I'd recommend using the Rules as Written (RAW).

The core rule books have an insert covering these opposed skill checks.

Coercion, Deception, and Leadership are opposed by Discipline

Charm is opposed by Cool

Etc.

If that doesn't cover it for you, Perception is a great skill. It is the skill of being (or becoming) aware of what is around you.

That said, if you're trying to model the skills used by fictional characters like Shawn Spencer from Psych or Patrick Jane from The Mentalist , I repeat; The Star Wars RPG doesn't model those skills. At all.

There might be some Jedi Mind tricks that do similar things (Sense? Foresee?) but as for the raw skilled perception of non-verbal cues? Nope.

IRL, this skill is a specialized form of Perception.

IN GURPS IV, I'd call it a Mental Hard skill based on Perception.

In Star Wars? I've got nothing.

Seeing through lies would fall under a despair result on the check (note improved unrelenting sceptic forces a despair)

Discipline would be if someone is trying to lie in order to coerce you. It's the acting of resisting social pressure, resisting charm would work the same way in my opinion.

However a straight up deception where it's not so much pressure but seeing through untruth should be perception or vigilance.

Is that raw? Huh...