When to use captions to convey information? Sometime, telling is better than showing. Use with care ... as with any technique.
Most showplayers (actors/actresses) are Collaborator Artisans (SeFx). Look at their behaviour. That said, Collaborator Idealists (NeFx) are statistically over-represented in the ones I interact with - this is not a complaint. :) This is likely due to my writing-humour style appealing to them. I've read "Directing Actors" by Judith Weston and I'm now on "Changing Direction" by Lenore DeKoven. The books seem Gamma quadrant valuing. Se (being in the moment, dynamics), Fi (relationships, motivation & subtext: feeling below the surface), Ni (through lines), and Te (scene objectives).