[delusional]

There is to my knowledge no vector signifying "truth" and therefore no vector to measure the distance from. You cannot get a "truthiness" measure out of these models, because they don't have the concept of truth. They use "likelyness" as a proxy for "truth".

You could decide that the text is "too unlikely" the problem there is that you'll quickly discover that most human sentences are actually pretty unlikely.

[astrange]

The article itself says there's a trait for hallucinations which can be reduced, which is the same thing as having one for truth.

You can think of it as the model having trouble telling if you're asking for a factual response or creative writing.