This study examines the degree to which low and high proficiency English as a foreign language (EFL) learners’ knowledge of base words (e.g. develop) overlaps with knowledge of their derivational forms (e.g. developer, redevelop) when reading. Low and high proficiency learners’ comprehension of derivational forms is also explored in relation to the frequency of occurrence of derivational forms and whether the derivational forms are presented with or without semantic context. A battery of meaning-recall tests measuring knowledge of base words and their derivational forms of varying frequencies of occurrence (high, mid, and low) in semantically contextualized and non-contextualized conditions were administered to 150 Japanese EFL learners. Results showed that learner knowledge of base words was not strongly indicative of equivalent knowledge of those base word’s derivational forms (i.e. low knowledge overlap). The analysis of knowledge overlap (Jaccard’s Index) showed that when participants knew a base word, they were likely to know its derivational form on average a little over 50% of the time. Mixed-effects ANOVA indicated that derivational forms’ frequency of occurrence in a written corpus strongly moderated their meaning recall. Learners’ lexical knowledge, however, only provided a negligible effect. Further, for both low and high proficiency learners, test items containing semantic context did not enhance learners’ meaning recall of derivational forms when reading.

中文翻译：

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检查 EFL 学习者对派生形式的理解：与基础单词知识、词频和上下文支持的重叠的作用

本研究考察了英语作为外语（EFL）水平较低和较高的学习者在阅读时对基本单词（例如“develop”）的了解与其派生形式（例如“developer”、“redevelop”）的知识重叠的程度。低熟练度和高熟练度学习者对派生形式的理解也与派生形式出现的频率以及派生形式是否带有或不带有语义上下文有关。对 150 名日本 EFL 学习者进行了一系列意义回忆测试，测量基本词及其在语义语境和非语境条件下不同出现频率（高、中、低）的派生形式的知识。结果表明，学习者对基本词的了解并不能强烈表明这些基本词的派生形式的等效知识（即知识重叠度较低）。知识重叠分析（杰卡德指数）表明，当参与者知道一个基本词时，他们平均有超过 50% 的时间可能知道其派生形式。混合效应方差分析表明，派生形式在书面语料库中出现的频率强烈调节了它们的意义回忆。然而，学习者的词汇知识的作用微乎其微。此外，对于低熟练度和高熟练度的学习者来说，包含语义上下文的测试项目并不能增强学习者在阅读时对派生形式的意义回忆。