The present study uses self-paced reading as a measure of online processing and an acceptability judgement task as a measure of offline explicit linguistic knowledge, to understand L2 learners’ comprehension processes and their awareness of subtle differences between the modal auxiliaries may and can. Participants were two groups of university students: 42 native speakers of English and 41 native speakers of Croatian majoring in L2 English. The study is part of a larger project that has provided empirical evidence of the two modals, may and can, being mutually exclusive when denoting ability (can) and epistemic possibility (may) but equally acceptable in pragmatic choices expressing permission. The present results revealed that L1 and L2 speakers rated the acceptability of sentences in offline tasks similarly; however, L2 learners showed no sensitivity to verb–context mismatches in epistemic modality while demonstrating sensitivity when processing modals expressing ability. Implications for L2 acquisition of modals and future research are discussed.

本研究使用自定进度阅读作为在线处理的衡量标准，并将可接受性判断任务作为离线显性语言知识的衡量标准，以了解 L2 学习者的理解过程以及他们对情态助词之间可能和可以之间的细微差异的认识。参与者是两组大学生：42 名以英语为母语的人和 41 名以克罗地亚语为母语的人，主修 L2 英语。这项研究是一个更大项目的一部分，该项目为“可能”和“可以”两种模态提供了实证证据，它们在表示能力（can）和认识可能性（may）时是互斥的，但在表示许可的语用选择中同样可以接受。目前的结果表明，L1 和 L2 说话者对离线任务中句子的可接受性进行评分相似;然而，L2 学习者对认识模态中的动词-上下文不匹配没有表现出敏感性，而在处理表达能力的情态时表现出敏感性。讨论了对 L2 模态习得和未来研究的影响。