Roerden identifies symmetrical dialogue like this: "Every question receives an answer." Symmetry suggests cooperation, and cooperation doesn't contain conflict or tension, one of the most important parts of dialogue. Roerden challenges writers to use asymmetrical dialogue, instead, or to begin with symmetrical dialogue and then jump to asymmetrical.
When the interviewer asks a question, in symmetrical dialogue, the interviewee would answer the question as fully as possible. In asymmetrical dialogue, the interviewee changes the subject, asks a different questions, maybe even a rhetorical one, or remains silent, refusing to answer at all. Here's an example from my thriller, Cassandra's Curse. The protagonist, Cassie, is speaking with a police officer after a traumatic event:
"Do you need a medic?" the female officer asked.
Cassie looked at the officer. Her name tag read Phelps. Or Phipps. Hard to tell. Tears clouded Cassie's vision, making reading difficult. Her hands shook from the adrenaline overload, but other than the pain of her scalp, she was unharmed. "No, I'm fine."
"Tell me what happened," Phelps/Phipps asked.
"I want to go home," Cassie said, clutching her coat more tightly around her body.
Granted, it's not the most tension-filled dialogue in the book, but it illustrates the point. Instead of telling the officer what happened, Cassie ignored the question completely and said what was on her mind. It also reveals a bit about Cassie's character, and mirrors another conversation that comes up later in the story between Cassie and a police detective.
Challenge: find a question-and-answer session in your WIP and identify the symmetrical bits, where every question is answered truthfully and fully. Then add some tension by inserting asymmetry.
-Sonja