This paper presents a perception experiment to measure the ability of Japanese children in fourth and fifth grade elementary school to recognize culturally encoded expressions of politeness and impoliteness in their native language. Audio-visual stimuli were presented to listeners, who rate the politeness degree and a possible situation where such an expression could be used. Analysis of results focuses on the differences and the similarities between adult listeners and children, for each attitude and modality. Facial information seems to be retrieved earlier than audio ones, and expressions of different degrees of Japanese politeness, including expressions of kyoshuku, are still not understood around 10 years of age.