Unconscious anchoring in maternal imitation that helps find the correspondence of a caregiver's vowel categories

摘要

It is a formidable issue how robots can show behaviors to be considered as the corresponding human's ones since the body structure is different between robots and humans. As a simple case for such a correspondence problem, this paper presents a robot that learns to vocalize vowels through the interaction with its caregiver. Inspired by the findings of developmental psychology, we focus on the roles of maternal imitation (i.e., imitation of the robot voices by the caregiver) since it could play a role to instruct the correspondence of the sounds. Furthermore, we suppose that it causes unconscious anchoring in which the imitated voice by the caregiver is performed unconsciously, closely to one of his/her own vowels and hereby helps to make the robot's utterances to be more vowel-like. We propose a method for vowel learning with an imitative caregiver, under the assumptions that the robot knows the desired categories of the caregiver's vowels, and the rough estimate of mapping between the region of sounds that the caregiver can generate and the region that the robot can. Through experiments with a Japanese imitative caregiver, we show that a robot succeeds in acquiring more vowel-like utterances than a robot without such a caregiver, even when it is given different types of mapping functions.