The purpose of this paper is to show our analysis of students' errors in elicited production tasks of the English progressive. Although the English progressive is one of the easiest forms to acquire, its ultimate acquisition of form-meaning mapping is still difficult for Japanese learners of English. The Cognitive Linguistics framework considers the utilization of our cognitive abilities as key factors in language acquisition. From the framework of cognitive linguistics, Langacker (1987) advocated Cognitive Grammar, focusing on grammatical aspects of languages. In terms of English aspect, he proposes the distinction between 'perfective' and 'imperfective' process. In a perfective process, properties (of a verb) change through time, while an imperfective process profiles a constant relation (Langacker 1987: 261). Therefore, so-called 'state verbs' designate imperfective process. Their stative nature fits into the simple present tense. When they are used in the progressive form, that will suggest some kind of 'changes' (Langacker 1987: 255-256). In order to investigate the nature of students' errors of English progressive, we asked Japanese college students to complete several sentences by changing verb forms under several situations/contexts (pre-test). After this task, we showed them audio visual teaching material of English progressive that we developed. Then we conducted the same type of tasks on the subjects again (post-test). We divided English verbs into three categories depending on their meanings and performance, e.g., activity verbs, achievement verbs, and state verbs. Achievement verbs focus on the end-point of a process. Their progressive forms suggest something is going toward the end-point, such as 'reach a mountain' or 'arrive at the station.' Among them, we chose the materials of achievement verbs and state verbs for our lesson because these two types are confusing for Japanese learners. After showing the moving pictures with voice recordings, we asked our students to perform the same sentence completion task. The resulting varied performances illustrates their different levels of abilities to link their understanding to performance. The significance of this study lies in our method of explaining erroneous understanding of English progressive by Japanese learners of English through an analysis of their production tasks. Moreover, the improved performance on the second task shows that our audio-visual material was clear enough for the students to understand English aspectual system.
