We conducted an experimental study of an English-experience program in which children regularly engaged in English-language activities in a Japanese elementary school over the course of 3 years. Three groups of children (first, third, and fifth graders upon joining the project) participated. The children engaged in Japanese and English aural digit-span tests in the first, second, and third years of the program. Results showed that the children's digit-span performance in English improved dramatically during their 3-year participation and that the increase was larger than that in Japanese. This finding was most pronounced in children in the middle group, and was discussed in terms of total exposure time to spoken English, the amount of after-school English activities, and the sensitive period hypothesis of a second language acquisition. We concluded that the English-activities program employed in this study was effective in facilitating the acquisition of phonological forms of English among Japanese students in elementary school.

Key words: Short-term memory, working memory, digit span, language-familiarity effect