The bits that come between the actual speeches in a dialogue section are technically called beats, though I more often refer to them as inbetweeny bits. They take the form of either an action or a thought or emotion - he said, putting his teacup down or she said, thinking he was so boring.
Here's a scene excerpt from A Single to Rome. Kimberley and Natalie have just been to a speed-dating evening. Natalie is getting over the breakup of her relationship with Michael. I've doctored it so there are two beats for each piece of dialogue - two actions or two thoughts or one action/one thought.
'So, what did you think? Did you meet the man of your dreams?' Kimberley said as they walked back to the car, high heels clicking on the pavement.
'You know Michael wasn't there.' Natalie pressed her fingers against her temples. Just her luck to get a splitting headache.
Kimberley glanced over to her. 'I quite liked a few of them. They weren't all bad.' She jiggled her car keys.
Natalie felt a pang of envy. Kimberley was always so positive. 'Which ones did you like?'
Kimberley put her head to one side and narrowed her eyes as if considering her options. 'Toby, he was nice, and Jerry. And Guy, and that one with the big hands, I think he was David - I got a bit confused in the second half.'
Natalie tried to think who she meant. A succession of men merged into one. 'Was he the shaggy one? No! Didn't you think he was a bit scruffy?
'I quite like that - I don't want them too prissy.' Kimberley giggled, and leant across to whisper in Natalie's ear. 'And you know what they say about men with big hands.
Natalie giggled too. She heard people say that many times before. 'But is it true?'
Kimberley raised her eyebrows and swung her car keys around on one finger. 'Only one way to find out.'
That's so dull to read. If you try reading it aloud, you can hear that the rhythm is all wrong, it's like a toddler banging a spoon on a saucepan, on and on and on. It's monotonous. It even looks monotonous on the page, each line roughly the same, lots of short paragraphs after each other. And, while I'm not making any claims to write high literature, this does come across as exceptionally trite. This is I actually wrote.
'So, what did you think?' Kimberley said as they walked back to the car. 'Did you meet the man of your dreams?'
'You know Michael wasn't there,' Natalie said.
Kimberley made a tsk noise. 'I quite liked a few of them. They weren't all bad.'
'Which ones did you like?' Natalie didn't think there'd been anyone who could raise a spark of interest in her. But that was unfair: all her interest was directed at Michael.
'Toby, he was nice, and Jerry. And Guy, and that one with the big hands, I think he was David - I got a bit confused in the second half.'
Natalie checked her card as she tried to remember. David, David, David... 'Was he the shaggy one? No! Didn't you think he was a bit scruffy?' She wanted to say slobbery.
'I quite like that - I don't want them too prissy. And you know what they say about men with big hands.' Kimberley raised her eyebrows at Natalie, who laughed.
'But is it true?'
'Only one way to find out.'
Just looking at it on the page it looks better. The speeches are broken up, and there are several which have no attributions, no actions, no thoughts.
Thought. Thought. Thought.
Action. Thought. Thought.
It's a pretty random pattern, and is all the better for it. We need to know what the characters are doing and thinking, but if we get everything it's relentless, a bit like sitting next to some twit at the cinema who feels the need to give a running commentary on the film. The bits of dialogue without any attributions, or beats are like breathing spaces in the prose.
They also speed up the pace. Immediately after this passage comes a longish paragraph of Natalie's interior thoughts which slows the pace down again. Fast, slow, fast, slow - readers want the variety or they get bored. Most writers - all? - read out their work either as they're writing or editing, or both. They can hear the rhythm of the beats and instinctively are looking for variety. Listen to the rhythms of your writing. Listen to your beats.