On the Dynamics of Overlap in Multi-Party Conversation

Overlap, although short in duration, occurs frequently in multi- party conversation. We show that its duration is approximately log-normal, and inversely proportional to the number of simul- taneously speaking parties. Using a simple model, we demon- strate that simultaneous talk tends to end simultaneously less frequently than in begins simultaneously, leading to an arrow of time in chronograms constructed from speech activity alone. The asymmetry is significant and discriminative. It appears to be due to dialog acts which do not carry propositional content, and those which are not brought to completion.