How do passive skill-checks work exactly?

[The Enigma]

I'm talking about those quick skill-checks that constantly appear during conversations without preemptively showing a percentage of success.

Somehow mostly successful ones seem to appear, and somehow the dice-rolls shown when hovering with your mouse always seem within a narrow range (often 10-13 according to my observations).

Rare exceptions aside, do only successful ones appear?

And how are they calculated? It seems like proper dice-rolls aren't even performed, and the game simply takes the median value of 2d6 (which is 7) before adding your stat value. For example, someone who has 5 Logic always seem to get a score of 12 for these skill-checks (7+5=12).

So again, how exactly do passive skill-checks work?

[Aria Athena]

My understanding is that there are 2 types of passive skill checks: the one that appear only if they are successful and the one appearing only if they are unsuccessful.

An example of the second kind is this: If you say "I could do this thing better" volition may say "no you can't", but only if you fail the check otherwise it will not appear at all.

There doesn't seem to be a roll for the passive checks. It usually just adds 6 to your skill, but I have also seen +5. Maybe there are also hidden bonus, like in white and red checks.

[The Enigma]

Indeed, failures only seem to show when there's a relevant negative consequence (however small it may be).

Thanks for the help, seems like I wasn't too far off with my initial impressions.

[Swiftdrake]

The number seems to be 6 not 7 (although 7 makes more sence as an average)