The writerly term is talking heads syndrome.
What does it mean?
Dialogue happens, but there’s nothing there, no sense of the where for setting, nor grounding of context or situation. Dialogue can be great, but if there’s no world setting, no place for it to happen, the mouthpieces can be set on a piece of white cloud, or a white board, or a bit of sky somewhere out there. It makes the whole conversation irrelevant because it can’t be real.
Yes, okay. It’s a story, but stories have to feel more real than the real world or the reader pops out and never goes back in. It’s a real world as it’s being read. We understand this, at least on a subliminal level. Generally, more so. If we can’t picture it in our mind, it isn’t real.
Which means if these talking heads ever come back to the planet (whichever grounding surface they need, whatever setting their world is contained within), do we feel anything for what happened? Do we believe?
No. Because that’s not the way it happens. More often than not, if it’s dialogue only (or with a couple of facial movements with the dialogue tags), then there’s only text, no context (the world stuff, why they’re in this place, how it affects them, how they demonstrate subtext through their interaction with the setting and each other), then there’s also no subtext.
Subtext is a big deal.
It’s the unspoken stuff that lies between words, outside the dialogue and tags. It’s the real meaning of what’s happening. Dialogue is chit-chat compared to subtext.
This is important stuff. I think every person understands that what is said is not all there is to the conversation. There are so many other things.
Manipulation, expectation, seeking, demanding, wheedling, guessing, using the words to harm or heal. There’s always so much more to what’s being said, and if the words don’t contain that by using the placement of setting, environment, attitude toward it, actions (real stuff, not just tics and hair-flicks), reactions, body language, etc.
It’s how we interact with the words through the things around us, including our body, their body, the things we use to block the other participant/s in the conversation — it all has meaning.
In effect, talking head syndrome is a waste of story words because it won’t mean anything to the reader, despite the world count.

Cheers. I’m off to the physio. See you soon.
I found this post very interesting, Cage. I agree with you. Dialogue is important in a book but it isn’t, and can’t be in my opinion, the whole story. I often thing of The Thorn Birds and how the author described the Australian outback, incredible! Difficult to do that with only dialogue.
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Difficult to understand the characters or how they think if all it is is chit-chat. I need to see the way they move, the way they avoid or bluff their way through the conversation. I always wonder what’s at the bottom of the words …
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We are soul sisters.
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