This study investigated how much practice is necessary for learners to attain durable second language (L2) grammar knowledge. Using digital flashcards, 119 participants practiced translating 12 sentences into an artificial language, followed by feedback, until they had typed all sentences correctly. Participants repeated this activity in one, two, three, or four relearning sessions on consecutive days. After a 14-day delay, all groups scored highly on a receptive test. However, scores on a productive test were substantially higher for groups with three or four relearning sessions. Accuracy tended to peak on the 3rd day of training. An analysis by individual training performance revealed that participants attained durable productive knowledge if they completed two sessions without errors, regardless of how many sessions they had performed in total. The findings provide a timeframe for processes described in skill retention theory (Kim et al., 2013) and suggest a performance benchmark to indicate when learners have gained procedural L2 grammar knowledge.

中文翻译：

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熟能生巧，但需要多少呢？再学习在第二语言语法习得中的作用

这项研究调查了学习者需要多少练习才能获得持久的第二语言 (L2) 语法知识。 119 名参与者使用数字抽认卡练习将 12 个句子翻译成人工语言，然后提供反馈，直到他们正确输入所有句子。参与者连续几天在一次、两次、三次或四次重新学习课程中重复此活动。延迟 14 天后，所有小组在接受测试中都获得了高分。然而，进行三到四次重新学习课程的小组在富有成效的测试中得分要高得多。准确性往往在训练的第三天达到峰值。对个人培训表现的分析表明，如果参与者没有错误地完成两次课程，无论他们总共进行了多少次课程，他们都将获得持久的生产性知识。研究结果为技能保留理论（Kim et al., 2013）中描述的过程提供了一个时间表，并提出了一个绩效基准来表明学习者何时获得了程序性 L2 语法知识。