The second language acquisition research has been investigating the effectiveness of recasts, a type of oral corrective feedback that consists of teachers' implicit reformulation of students' speech errors. The present study was conducted targeting Japanese as second language, to examine how recast facilitates the correct use of different type of grammatical structures; Japanese honorific expressions, and particles.

The data come from one-to-one tutorial sessions between the researcher and the participants conducted in March 2019. The participants were 16 Polish university students majoring in Japanese studies. They engaged in a tour-guiding role play which was designed to elicit various honorific expressions and the route-marking particle (e.g., toori o aruku), and they received recasts on their erroneous use or avoidance of the targeted features. Their performances were video-recorded. They were then asked to watch the video clip and make comments on their recast episodes (i.e., stimulated recall).

The participants' performances were analyzed focusing on their immediate responses to recasts, and on the occurrences of appropriate use of the targeted structures after receiving the recasts. The participants' recall comments were coded for the accuracy of understanding the nature of errors.

Results indicate that recasts triggered participants' primed production of honorific expressions when continuing the role play. It is also indicated that the linguistic knowledge of the participants and the saliency of the targeted features were significant factors that determined the impact of recasts. Also, the influence of their first language was found on the nature of the errors and its understanding.