“…It can be explained that vocabulary knowledge (size, depth, antonym) has its own correlation with speaking proficiency (fluency, accuracy, etc.) Oya et al (2009), with research focusing on students' language contacts outside school (duration of stay, contact with friends, various places outside school) have correlation with speaking ability (fluency, accuracy, and complexity). As the participants are Japanese residing in an English-speaking country, this shows how much language contact outside of education institution has impact on speaking performance.…”