“…This is not usually discussed in relation to L2 acquisition research since one generally assumes that once learners have reached a certain proficiency in the L2, they will retain that proficiency, but studies dating back to Cole (1929) have been concerned with the loss of foreign language skills by high school students during summer vacation after completing a language course. In more recent L2 attrition studies, researchers have been interested in returnees who have spent longer periods abroad (e.g., Yoshitomi, 1992Yoshitomi, , 1999Tomiyama, 1999Tomiyama, , 2009. Typically, people who stay a number of years in an L2-speaking environment gain a certain level of proficiency.…”