Reducing Speech Collisions by Using an Artificial Subtle Expression in a Decelerated Spoken Dialogue

We argue that spoken dialogue systems or communication robots do not need to quickly respond verbally as long as they quickly respond non-verbally by showing their internal states by using an artificial subtle expression. This paper describes an experiment whose results support this point. In this experiment, 48 participants engaged in reservation tasks with a spoken dialogue system coupled with an interface robot using a blinking light expression. The expression is designed as an artificial subtle expression to intuitively notify a user about a robot’s internal states (such as processing) for the sake of reducing speech collisions as consequences of turn-taking failures due to end-of-turn misdetection. Speech collisions harm smooth speech communication and degrade system usability. Two experimental factors were setup: the blinking light factor (with or without a blinking light) and the reply speed factor (moderate or slow reply speed), resulting in four experimental conditions. The results suggest that the blinking light expression can reduce speech collisions and improve user impression, and surprisingly that users do not care about slow replies.