Human entrainment of rate of utterances when communicating with an auto response system

Entrainment, a physical phenomenon in which one individual\´s expressed information synchronizes with another\´s and vice versa, can be observed between two communicators who are in smooth interaction. In this study, we focused on the "rate of utterances" as communicators\´ expressed information, and conducted two experiments to observe whether entrainments exist in the rate of utterances in speech dialogs between (1) human and human and (2) human and an auto response system. Subjects were asked to read given dialog scripts with other subjects or an auto response system that replied with different rates of utterances. The results revealed that (1) when the system\´s rates of utterances were faster, the subjects produced faster rates of utterances, (2) when the system\´s rates were slower, subjects spoke at slower rates. These results suggest the existence of entrainments of rates of utterances in speech dialogs between human and an auto response system.