What Spaced Learning is Effective for Long-Term L2 Vocabulary Retention?

抄録

　　The present study aims to compare the effects of expanding, equally-spaced, and contracting retrieval practice on L2 vocabulary learning. Group A (n = 34) learned 20 English and Japanese word pairs (e.g., ligament-jintai) under the expanding schedule (Day 1, 1, 8, and 22). In a similar way, Group B (n = 19) and Group C (n = 29) learned the same target words under either the equallyspaced (Day 1, 8, 15, and 22), or the contracting schedule (Day 1, 15, 22, and 22), respectively. Twenty-one days after the last learning session (Day 43), all the groups took a delayed post-test in which they were required to retrieve Japanese meanings for the target words (e.g., ligament:_____?). The results showed that: (a) Group A had a better score than did Groups B and C after the second learning session; (b) Group C outperformed Groups A and B after the fourth learning session. (c) However, no significant difference was observed between the three groups in the delayed test. These findings indicate that the length of the interval between each vocabulary session does not matter for long-term L2 vocabulary retention as long as learners are given three or more spaced learning sessions.