Mohammad Naghizadeh
Ahmad Alibabaee

Some theories of second language learning associated with Universal Grammar(UG), especially those which claim that UG is not or partially available believe that some syntactic features, which fail to be reset or reinstantiated in L2, are the major causes for the problems of learnability and even teachability. As an instance, Interpretability Hypothesis proposed by Tsimpli and Dimitrakopoulou (2002) claim that interpretable features are accessible to the L2 learner whereas uninterpretable features are difficult to identify and analyse in the L2 input due to persistent, maturationally-based, L1 effects on adult L2 grammars (Tsimpli and Dimitrakopoulou , 2002, p. 212). In this hypothesis the distinction is made between interpretable at the LF syntactic interface and PF interface. Accordingly, features which are interpretable at logical form interface in both first and second languages are accessible, even though they are not realized or spelled out in either language.The current study adopted a Universal Grammar approach in terms of parameter resetting to find out whether or not explicit teaching can make a significant progress in developing the article system of English by EFL learners. The parameter in question was article choice parameter, which distinguishes between specificity and definiteness in languages. Based on this parameter, Persian encodes specificity whereas English encodes definiteness, hence, native speakers of Persian who are going to learn English need to shift from specificity to definiteness.The study was carried out in a big language institution in Izeh (Iran),and 22 advanced students have participated after taking a 100 item Oxford Placement Test (OPT). A 00 item pretest indicated that despite being massively exposed to article system of English, the participants lack a good knowledge of articles. Three sessions were allocated for explicit instruction over three days, one session a day, to see whether or not explicit instruction can affect the way learners use the articles. A posttest then was administered and the mean comparison of pretest and posttest was done through a paired t-test. The resulting value revealed that the participants have made a significant progress.The findings of the study were all in favor of Interpretability Hypothesis, and the students could manage to shift from specificity to definiteness. However, the students failed to gain full mastery over the using articles even after the treatment. To see whether or not it is related to parameter resetting or not, the analysis of students’ errors in terms of different uses of articles in both pretest and posttest was done following Liu and Gleason’s (2002) study. At the end, it was found that the students have mostly problems with cultural and situational uses of article, which are associated with discourasl features rather than syntactic features.