Abstract:
Persian L2 learners of English over-passivize the unac-
cusatives. Therefore, it is necessary that teachers identify erroneous
over-passivization of unaccusatives and provide the necessary explana-
tion of the differences between unaccusatives and unergatives. Issues
such as type of instructions provided by teachers in the Second Lan-
guage Acquisition (SLA) classrooms still suffers from unanswered ques-
tions. This study focused on the acquisition of the differences between
unaccusatives and unergativesby intermediate and advanced learners
before and after receiving oral Corrective Feedback (CF). 106 students
who scored 1 standard deviation below and above the mean score of
the quick Oxford placement test (SD= 6.11, mean= 36.94), and also
passed an elimination test examining their knowledge of passive forma-
tion rules, were selected as the participants. They were divided into 4
groups (3 experimental and 1 control) according to the type of oral CF
they were supposed to receive and the university courses they had to
enroll in. A Written Elicited Production Task (WEPT) and a Grammat-
icality Judgment Task (GJT) were administered as the pre-tests. Each
experimental group received one type of oral CF as the treatment (ex-
plicit, implicit, or mixed) and the control group received no CF. Then
the WEPT and GJT were administered as the post-tests. The results
revealed that while students had the ability to judge the grammaticality
of the sentences with unergatives before receiving oral CF, they did not
have such ability for sentences with unaccusatives, and it was only after
receiving the oral CF when they acquired the required knowledge