Is it just me... or do other people find it a little confusing as to what either of these actually mean sometimes? 
 
Most of the time it makes sense, and I'm coming into this with no real example, but I'm finding occasions where I've pressed "Truth" and Cole has responded in a doubtful manner... and vice versa? 
 
I'm just finding myself more and more as I go through the game just completely stumped as to what to press. It also feels like some dialogue from the NPC's are relatively unrelated to the case, yet the game still wants me to doubt or truth them. 
 
I'm really loving this game, but the interrogation sequences seem so trial and error at times that it gets a little frustrating.

Truth - you think the dude's telling the truth 
Doubt - you think the dude's telling a lie but you don't have any evidence to disprove his lie 
Lie - like the above but you have evidence 
 
The game tells you this during the tutorial missions and in the instruction manual.

It's not just you.  The number of people having trouble with this suggests that either there isn't any consistent logic behind it, or the game just doesn't explain the system well enough.

Sometimes when you select Truth, it leads onto another question which is asked as if Cole doubts the person, so I totally get the confusion. I base everything on facial expressions and/or evidence.

Truth - you think the dude's telling the truth Doubt - you think the dude's telling a lie but you don't have any evidence to disprove his lie Lie - like the above but you have evidence  The game tells you this during the tutorial missions and in the instruction manual.

@rjayb89 said:

Truth - you think the dude's telling the truth Doubt - you think the dude's telling a lie but you don't have any evidence to disprove his lie Lie - like the above but you have evidence  The game tells you this during the tutorial missions and in the instruction manual.

This.

Even the facial expression stuff ain't consistent. Sometimes the person will be looking around the room, with a smug grin on their face so I doubt them... yet the correct answer is truth. If you follow the instruction manuals 6 step guide to judging people... you'd get a lot of questions wrong.

I never really had a problem with it really. Most of them seemed to make sense even when I got it wrong and replayed the case the correct answer would make sense. Sometimes I even noticed that dialogue from a previous conversation with someone else can help you know if a later character is lying even if said dialogue isn't recorded as a clue.
 
You just need to pay very close attention at times. 
Also,
@rjayb89 said:

Truth - you think the dude's telling the truth Doubt - you think the dude's telling a lie but you don't have any evidence to disprove his lie Lie - like the above but you have evidence  The game tells you this during the tutorial missions and in the instruction manual.

Sometimes I want to accuse them of a lie, and then they say something that kind of throws me off and makes me think the evidence I was going to use is irrelevant to the question asked. Or sometimes, I'm not sure if I should present certain evidence, because I'm already asking about it so it doesn't seem like it would advance anyhing...

If I am not really sure, I go by the look of the person - if he is calm and straight (can even be sad or something, but not twichy), it's truth. 
 
If the suspect show some signs of a lie and I am not sure if I am supposed to pick doubt or lie, i choose the lie option which allways gives you another line of dialog, specifing what you need to prove. If there is no evidence to use to prove that particular fact, back up by pressing B (or circle I suppose) and go with doubt. If its wrong, you either didn't have the right clue to prove a lie or you just didn't pick realise what to pick. 
 
I would say I pick about 90% correct answers so far (last case of the Homicide desk) so this works pretty well.  It is a little gamy interogation system.

@Axxol said:

@rjayb89 said:

Truth - you think the dude's telling the truth Doubt - you think the dude's telling a lie but you don't have any evidence to disprove his lie Lie - like the above but you have evidence  The game tells you this during the tutorial missions and in the instruction manual.

This.

Neither of you are getting my point.

Truth - you think the dude's telling the truth Doubt - you think the dude's telling a lie but you don't have any evidence to disprove his lie Lie - like the above but you have evidence  The game tells you this during the tutorial missions and in the instruction manual.

I'm just confused wether I have to choose Lie or Doubt

Well i'm glad I am not the only one having problems with this. Although I seem to be a failure detective is general as I hardly get any of the questions correct...lol.

I'm just confused wether I have to choose Lie or Doubt

I'd actually be kind of disappointed if the game made it easy enough that you could read characters and feel like you've got them pinned down every single time. It's more realistic this way, and it doesn't really bother me too much to miss a question. I'll probably play it through a second time with all of the answers just to see how that goes. 
 
It can be frustrating reading people, but yo, that makes it fun!

I find it harder to distinguish Truth from Doubt, because if you've managed to collect all the clues, you should be able to figure out when the suspect is lying.

I found it pretty easy, people's trouble with it might be a testament to their lack of ability to read people.  
 
When they're looking at you dead straight, it's the truth, when they're not, it's either a lie or doubt, if you have evidence, use lie, if you don't use doubt. The dialogue after you say "lie" gives you a clue of what you need to select to accuse them. 

I find it funny when people say this has any bearing on your real life ability to read people, then go on to say how apparently blindingly obvious and simplistic the game makes it (ie. not realistic in the slightest). Although I don't think it has any relevance to the real world, I think it would be more accurate to say the people finding it easy (and who think the reading process in the game crosses over to the real world) are the ones with a worse real world ability of reading people, and the ones finding it difficult are better at it, because they're ignoring the ridiculously obvious signs and looking for more specific tell-tale or idiosyncratic signs that simply aren't there to be found. 

The best advice I received regarding the interrogations is to stop thinking so deeply about it.  Just go with your initial instinct and you'll usually get it right.  When I started the game I was averaging maybe 50% on the interrogations because I was over thinking it and looking for hints and subtleties that aren't there...once I just kind of "went with it" I started doing much better, now I'm averaging around 85% of so on most cases for the interrogations.

You just have to stop over-thinking the difference between truth and the other 2.  So far there have only been a couple interviews where I found the guys to be "good liars" in that they didn't act like a freaking chihuahua on speed when they're lying.  You should be able to quickly weed through truthful or deceitful answers.   Theres virtually no subtlety to liars, except in rare instances.
 
 The real challenge of the game is lie or doubt, and picking the exact right piece of evidence needed to prove a lie.  IMO there needs to be more degrees of failure, because I usually have something different in mind than what the game is looking for.   The game tends to swing back and forth on what constitutes evidence for lying.  In one case it will be something seemingly circumstantial, and in the next you try a similar clue and fail.   There are plenty of times Ive picked "doubt" and failed because i thought none of the evidence as really strong enough to disprove whatever was said,  and on the very next question its equally vague but needs doubt instead of lie because the evidence isn't there.  A couple times there was a complete disconnect between my initial question, the lie, and then the evidence it wanted.
 
Im loving the game BTW, and will likely buy any DLC they feel like putting up, but I also think they can do better in another iteration.  I'm in an odd spot, I want the liars to be harder to deduce in more cases, but I want the degrees of failure on picking evidence to be expanded so I can present more than one piece(making it easier), or even have "failures" result in allowing me to present more etc.  Its a great game, and the interrogations are equally my favorite, and the most frustrating part, just for these reasons.  

The amount of people having trouble with this is staggering... I mean, it's self-explanatory. The game even tells you what they mean, and makes it so unbelievably easy for you most of the time. Use your brain guys, I know it's hard but trust me you'll have more fun that way.

I think some of you are oversimplifying the problem here. It's not as simple as "if they look at you without fidgeting, you press TRUTH; if they move their eyes and look nervous, you press DOUBT or LIE." 
 
Example (minor spoilers): 
 
In the case The Fallen Idol, you go to the hospital to talk to the young girl that was in the car. Cole asks her the question, "Do you remember where the abuse took place?" She answers, "No, it's really hard to remember." And her eyes look all around the room. It seems obvious that she knows more than she's letting on, but you have no evidence to prove that, and so the natural option according to the "move eyes, hit doubt" logic is to select DOUBT. Cole then proceeds to get super harsh with her and say she needs to grow up. She clams up and says she remembers "lying on a stone slab." The correct choice in this case is TRUTH, in which case she says, "Well, I do remember a mermaid," which adds a clue to your notebook. 
 
This is the kind of scenario that is so confusing. Her eyes are going everywhere, she seems to be withholding something, but if you select DOUBT, Cole goes fucking crazy and makes the person close up and not give out the information.  
 
The Truth/Doubt/Lie system is starting to really get on my nerves, which is a damn shame because it's bringing the rest of the game down. 
 
 
Another example from the same case: 
 
In the beginning, you're speaking to June Ballard. You ask her if she has any info about Mark Bishop, to which she replies, "Don't worry about that, my husband will deal with him." What kind of choices are TRUTH, DOUBT, and LIE in that situation? She's not putting forth any info; she's simply making a statement. The correct choice in that case is DOUBT, which doesn't make much sense. Not only do none of the options make sense for the statement, but she looks straight at Cole, which is supposed to be an indicator that you should select TRUTH. 
 
It all seems to be arbitrary.