Research on the effect of implicit and explicit instruction on developing learners’ explicit knowledge by the use of measures of explicit knowledge abounds in the literature. However, measuring learners’ implicit knowledge employing fine-grained measures has rarely been the concern of researchers in the field. Therefore, the present study is an attempt to scrutinize the effectiveness of implicit and explicit instruction through administering a Word Monitoring Task (WMT), as a more valid psycholinguistic measure of implicit knowledge. The necessary data were collected from 47 pre-intermediate participants in three different groups, i.e., (1) the implicit group received textually enhanced texts of verb complementation, (2) the explicit group was presented with metalinguistic explanations and examples of the target feature, and (3) the control group was deprived of any instruction. The results of the mixed between-within subjects ANOVA revealed that although both implicit and explicit instructions facilitated the development of the implicit knowledge of the target feature, the learners in the explicit group outperformed their counterparts in the implicit and the control groups in both the immediate and delayed post-tests. Moreover, the results indicated more durable effects of implicit instruction compared with those of explicit instruction. Overall, the findings provided evidence for the superiority of explicit instruction and the long-term effect of implicit instruction in developing relevant knowledge of verb complementation. The findings of the study can benefit both teachers and learners in developing teaching/learning strategies to improve and facilitate the grasp of both explicit and implicit knowledge.
