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Volume 11. Issue 4
Article 4

Title
A Comparison of the Effects of Corrections on Definite/Indefinite Articles and Regular/Irregular Past Tense Forms: A Case of Iranian EFL Learners

Authors
Azizollah  Dabaghi
University of Isfahan, Iran
Mansoor Tavakoli
University of Isfahan, Iran

Bio Data: 

Azizollah Dabaghi completed his doctoral studies in language learning and teaching at the University of Auckland, New Zealand.  He has been involved in teaching English at different levels in Isfahan, Iran for the last 20 years.  Currently he is working as an assistant professor of applied linguistics at the University of Isfahan, Iran.  His research interests include second language acquisition, form focused instruction, and corrective feedback.

Mansoor Tavakoli is a PhD student in TEFL at Isfahan University, Iran.  He is an assistant professor and has taught TEFL courses at three levels of B.A, M.A, and PhD at the University of Isfahan for 12 years.  His research interests are teaching and assessment.

Abstract
The major purpose of this study was to investigate the effect of error correction on EFL learners’ acquisition of some grammatical features. More specifically, the study looked at the learning effects of correcting learners’ errors on definite and indefinite articles as well as errors on regular and irregular past tense verb forms. Data for the study were collected from 56 intermediate level students of English as a Foreign Language in Iranian private language school settings. Through an oral interview, each participant was required to read and then retell a written text in their own words. During or following the interview the examiner provided the participants with immediate explicit, delayed explicit and immediate implicit corrective oral feedback on their grammatical errors. Individualized multiple-choice tests focusing on the errors that had been corrected were constructed for each participant and administered. A comparison was made between the learners’ scores on the test items that measured definite and indefinite articles as well as regular and irregular past tense forms in order to assess the impact of corrective feedback on these linguistic features. This comparison was made by post-hoc analysis of the final tailor-made tests. The results show that when corrective feedback is given, the irregular past tense form is learnt before the regular past tense and the definite article ‘the’ is learned before indefinite articles ‘a’ and ‘an’. This finding lends support to the arguments put forth by of Krashen, (1977), Andersen (1978), and Dietrich, Klein and Noyau, (1995) that confirmed the role of negotiation as well as to the role of saliency and individualized attention in language learning. The results of the study also have some implications for both second language acquisition and language pedagogy.

Key Words: Definite/Indefinite Articles; EFL Learner; immediate explicit, delayed explicit and immediate implicit corrective feedback; Regular/Irregular Past Tense Forms; Second Language Acquisition; error correction.

1. Introduction
With the advent of communicative language teaching (CLT), the attention of most teachers and learners shifted from accuracy to fluency in attempting to learn a second language. In other words, because of the tendency of both learners and teachers, especially in recent years, towards fluency over accuracy, attention to the development of grammar in L2 has been neglected. However, this has caused a number of problems in terms of students learning some grammatical features correctly, such as definite and indefinite articles and regular and irregular past tense forms. For instance, although learners have explicit knowledge of grammatical features, they still make errors in their use. The presence of such grammatical inaccuracies in learners’ production of language makes the provision of corrective feedback essential, since it helps learners notice the incorrectness of the form(s) they have used. This, as a result, enables them to modify their hypotheses about the target language (Oliver, 1995). The present study attempts to investigate the effect of immediate explicit, delayed explicit and immediate implicit corrective feedback on the English article system as well as regular and irregular past tense forms as demonstrated by Iranian EFL learners who are at the intermediate level of proficiency.

2. Theoretical Background
One of the central points of interest for teachers and researchers has always been errors made by language learners. In fact, according to the cognitive view of language learning, errors made by L2 learners are signs of progress and not impediments (Dulay & Burt, 1975). If students commit errors, teachers should give them corrective feedback; and this would promote authentic interaction between them. 
   According to Polio et al. (2006), the role of corrective feedback in second language acquisition (SLA) has long been an issue, especially in the interactionist approach, which claims that the feedback through interaction is a driving force for learning. Mackey & Gass (2006) state that in Long’s (1996) interaction hypothesis of SLA, interaction, (particularly with a more competent interlocutor), facilitates L2 development because it connects input, internal learner capacities (e.g. selective attention) and output efficiently. It stands to reason, therefore, that corrective feedback (both its interpretation and its role in L2 development) plays a crucial role in interaction-based research.
   N. Ellis (2005) argues that both conscious and unconscious processes are involved in every learning sequence. In his connectionist model, in order for explicit learning to take place, some degree of attention is needed. The explicit learning can then be turned into an implicit one and enters implicit memory (Ellis, 2005). R. Ellis et al. (2006) suggest that providing students with corrective feedback constitutes an ideal context in which both conscious and unconscious learning are involved together in SLA. Moreover, in such a learning situation, the targeted structure (the one that is supposed to be learnt) will enter implicit memory.
   Conscious attention is crucially important in learning and does not take place unless features are made noticeable. Perceptual salience is the term used for when learners’ attention is drawn to language forms. It is one of the main contributing factors for drawing learners’ attention to grammatical features. There are several factors involved in salience: irregularity, stress, and frequency of input (Gass & Selinker, 2001).
   Let us now turn our attention to the variables under investigation such as the role of immediate explicit, delayed explicit and immediate implicit corrective feedback in learning some grammatical features in English. These features are definite and indefinite articles and regular and irregular past tense forms, which will be fully described and delineated in the following sections.

2.1 Regular Past Form vs. Irregular Past Form
Previous research has shown different findings with respect to these two features. Some studies found that the regular past tense form is learned before the irregular (Dulay and Burt, 1975; Larsen-Freeman, 1975; Hakuta 1974). Some other research shows that the irregular past form is learned first (Krashen, 1977). Still some other research using group scores (scores obtained by a group of learners) shows that the irregular past form is learned before the regular, but learners’ individual scores showed that there is no order between these two features (Andersen, 1978). Finally, the fact that the irregular past tense form precedes the regular form was confirmed in a longitudinal study of (largely untutored) adult learners of five target languages (Dietrich, Klein and Noyau, 1995).
   A possible factor in learning language features may be the degree of novelty that a form holds for a learner. The proponents of contrastive theory believe that similarities between the features in learners’ native language and the target language lead to learning ease, whereas differences lead to learning difficulty (Brooks, 1960). This theory was subsequently rejected and proved to be invalid (Corder, 1975). In contrast, Kleinmann, (1977) suggested that the difference between the forms in the learners’ native language and the target language may cause a novelty effect, which promotes SLA.

2.2 Definite vs. Indefinite Articles
Research in the domain of article acquisition comes from two different areas. Some research is not specifically on article acquisition, but is primarily concerned with morpheme acquisition (Dulay and Burt, 1973; Brown, 1973; Hakuta, 1976; Huebner, 1979, 1983; Tarone 1985; Master, 1995). Most of these studies show that the acquisition of the definite article takes place later than the indefinite. There is also research that has been exclusively designed to study article acquisition (Master, 1987; Parish, 1987; Tarone and Parish, 1988; Thomas, 1989; Liu and Gleason, 2002). These findings are mixed depending on whether the overuse assumption or the accuracy assumption is used. Despite discrepancies of the findings of Parish, Master, and Thomas, they concur that ‘a’ is acquired later than ‘the’. Chaudron and Parker (1990) also provide evidence that Japanese learners acquire ‘a’ later than ‘the’.
   It has generally been observed that children possess an innate tendency to distinguish specificity from non-specificity. Presumably, this tendency emerges from a very early age as part of their L1 cognitive linguistic development (Brown, 1973; Maratsos, 1971, 1976; Cziko, 1986 cited in Butler, 2000). Furthermore, this semantic notion connects somehow with the external attributes (‘the’ and ‘a’).
   This hypothesis can be extended to the acquisition of articles among adult second language learners. The ability to distinguish specificity from non-specificity already exists among adult second language learners due to early childhood cognitive linguistic development in their L1. Also, as Huebner (1985) and Master (1988) suggested, L2 learners initially might associate specificity (SR=specific referent) with hearer knowledge [HK], in contrast to children acquiring the English article system as part of their L1. In other words, the semantic concepts of definiteness and indefiniteness already exist, what learning does is to connect these semantic concepts to the new external attributes (the article forms, ‘the’ and ‘a’).
   According to the COBUILD frequency count, in a corpus of 20 million English words, the definite article ‘the’is by far the most frequent word, with a frequency rate of 25.1% (Sinclair, 1991). The indefinite article, however, is the fifth most frequent item with a frequency rate of 10.1%. Frequency has been proposed by some research as one of the features that causes learners to notice forms (Bardovi- Harlig, 1987; Day & Shapson, 1991; Trahey and White, 1993; N. Ellis, 2002). These studies show the benefits of instruction that focuses on the frequency of troublesome features (Doughty and Williams, 1998).
   Concerning the theoretical backgrounds of the issue under study, the major question is to examine the effect of immediate explicit, delayed explicit and immediate implicit on the learning and use of frequent grammatical features. This will be further separated into minor questions below.

2.3 Research questions
In relation to the major purpose of the study, which was to investigate the effect of corrective feedback on learning and using the article system and regular/irregular past tense forms in English, two research questions were addressed. They are as follows:
1). Is the correction of indefinite articles, ‘a’ and ‘an’ more effective in Learning than the definite article ‘the’?

2). Is the correction of the regular past tense form ‘ed’ more effective in language learning than the irregular forms?

   In order to provide plausible answers for the aforementioned questions, a meaning- based study was conducted which will be described and explained in the next section.

3. Methodology         
3.1 Participants
A total of 56 learners (from among a population of 300 students) from seven language institutes with 12 upper-intermediate classes participated in this study. The reason for choosing these classes was because the numbers of learners who could talk well were naturally higher in such classes. To determine the general proficiency band in the study, a standard test of grammar was used. This 40-item test was selected from Section 2 (Structure and Written Expression) of the TOEFL test. Those scoring between 50 and 70 were called on to participate in the research. The reason for choosing this test was that, (according to the information provided by TOEFL) the reliability is relatively high (0.88).
   The research was conducted at seven private language institutes in Isfahan, Iran. These research sites were chosen because, in general, this research was initially intended to investigate error correction among EFL learners (that is, those who learn English as a foreign language in an environment where English is not spoken as a first language).
   The demographic information of the learners showed that they averaged about 22 years of age (with some as young as 17 and others as old as 33). The female students accounted for 66% of the sample population, while males were 34%. Forty percent of the students in these classes planned or hoped to continue their education at universities abroad, and for this reason, they pursued their language learning very seriously. 90% of the learners believed English was important for their higher education in Iran.

3.2 Materials
In the current research, for the purpose of eliciting errors, two passages were designed. They both have general topics; namely: ‘Diamonds Are forever’ and ‘Britain’s Unluckiest Criminal’. ‘Diamonds Are forever’ is more of a factual type of passage containing information on figures, dates, and names of some relatively known geographical places. ‘Britain’s Unluckiest Criminal’ is a narrative about the course of events in a man’s life. Each one of the two comprehension passages contains 240 frequently occurring words, 20% of which are function words and the rest consist of lexical items and proper nouns. These two passages are structurally and lexically of the same intermediate difficulty level. The difficulty levels of these passages were calculated by using the SMOG Readability Formula and the Smog Conversion Table. The levels were appropriate for the participants for a number of reasons. Firstly, the participants were upper-intermediate learners whose reading comprehension and speaking ability was not high enough to be able to understand and talk easily about passages containing higher levels of difficulty with relative ease. Thus, the passages were easier than the levels at which the learners were currently working. Secondly, they were learners at private schools and not at universities. Therefore, they had not been previously exposed to passages with higher degrees of difficulty.
   A number of individualized tailor-made tests were constructed based on the errors typically made by the learners. Every learner did two tailor-made tests, each consisting of a number of test items. The number ranged from 3 to 13 depending on the errors made by the learners in their task reconstructions and also on the instructor’s ability to identify the relevant errors. All test items were multiple choice questions that included a correct answer and three distractors. The main reasons for choosing multiple choice item tests were that multiple choice item tests have the advantages of ease, objectivity and reliability of scoring. However, the tailor-made tests had a weakness arising from different weightings of the test items. This situation occurred because each item in each tailor-made test was based on one error correction episode the learner had. So, if a learner had three error correction episodes in the reconstruction task, that learner had three items in his or her tailor-made test. If a learner had five error correction episodes in the reconstruction task, that learner had five items in his or her tailor-made test. A possibility would have been to increase the number of test items in the tailor-made test (for example, to provide two or more items on each type of error and in this way have the tests contain the same number of items). However, this was not practical, since the tests were individualised and the items had to be prepared very soon after the error correction sessions. There would not have been enough time to produce a large number of tests items.
   Below, we will fully delineate the experiment that was conducted in this study.

3.3.1 Immediate Explicit Correction
With this type of error correction method, as soon as learners makes an error, the teacher immediately steps in to correct them and to provide the learners with the correct form as well as an explicit metalinguistic explanation of the rule related to this form (Lyster, 1998) For example:
Learner: He buy a ticket of airplane.
Teacher: OK He bought an air ticket, an airplane ticket. You should use the past tense form here. The past tense is ‘bought’. OK?
L: He went and bought an airplane ticket.

3.3.2 Immediate Implicit Correction
Implicit correction refers to the process of providing the learner with indirect forms of feedback. After an error is made by a learner, again the teacher immediately steps in to correct them, but implicitly (Lyster, 1998). The implicit feedback provided to the learner in the present research was in the form of recast – the correct reformulation of the learners’ erroneous utterances. The following error correction episode is an example of immediate implicit correction:

Learner: Carson was a man and a local businessman and everybody thought he was honest man, but suddenly he invest and he fell in difficulty.
T: He invested his money in a business.
Learner: Yes, he invested his money in a business.
T: What kind of business was it?
Learner: I don’t know...

3.3.3 Delayed Explicit Correction
With this type of error correction, when learners make an error, the researcher waits till the learners’ attempt to reconstruct the text has finished (Lysre, 2004). In fact in this study, the teacher avoided correcting the error while the learners were still talking about the content of the passage. He only made rough notes of the errors made by the learners. Later, the correction was carried out explicitly using explicit corrective moves; that is, by providing the learner with the correct form together with a metalingual explanation of the rule for the correct form. The error correction in the following episode took place 15 minutes after the error was made.
T: Thank you very much for your talk about the passage. If you allow me, I would like to draw your attention to some of the mistakes you made during our conversation. Is it OK?
L: Yea, ok.
T: For instance you said, ‘He feeled depressed’.
L: Yes.
T: You should say, ‘He felt depressed.’ OK? The past tense of feel is ‘felt’ not feeled.
L: Right.

3.3.4 Test-Item Construction
A few words about how the construction of the tailor-made tests used in this study were made seems warranted. Errors made by learners included many cases of regular and irregular tense forms as well as definite and indefinite article forms. Multiple choice test items were constructed based on error correction episodes. The following examples of test items were constructed on the basis of such error types:

(Immediate / Implicit)

Table 1: Irregular Past Tense

   Options used for such items needed to be of the same class of grammatical features to make sure that the test item would measure one particular aspect of the error corrected by the teacher. For example, errors in the use of tenses can often be confused with errors in voice which is represented by active/passive forms of verbs. However, it was also important for the items to include developmental features as distracters. Therefore, the distracters used in these items could include active or passive forms. Furthermore, it was decided that other distracters be chosen from the tenses that are generally within the active production of learners at the intermediate level.
(Immediate/Explicit)

Table 2: Articles

Every test item that was constructed to measure the correction of article errors, generally consisted of the same four options throughout the study. These four options, as indicated in Table 2, are: ‘a’ ‘the’, ‘an’, and ‘blank’.

3.4 Analysis
Overall, there were 112 tailor-made tests, for both passage reconstruction tasks, administered to the learners. They included a total of 675 test items measuring 675 error correction episodes. Of this total number, there were 175 items measuring error correction episodes related to errors of definite/indefinite articles and regular/irregular tense forms.  The following table shows the number of such errors related to immediate explicit, immediate implicit and delayed explicit types of feedback:

Table 3: Number of Errors in Each Type

Similar to Ellis et al., (2001), an error correction episode is defined as an interlude between the learner and the teacher in an interaction. It is triggered by an error made by the learner and corrected by the teacher. The error correction ends when the interaction returns to the topic of discussion. In addition to the criteria mentioned in this definition, the following two points were considered in identification of episodes: 1. Error correction episodes included only teacher-corrected errors and not self- corrections.2. Each error correction episode included only a single error that was addressed by the teacher.

After the reconstruction and error correction episodes, the recorded sessions were copied onto a computer program that enabled the researcher to listen repeatedly to the recordings. Detailed transcriptions of the error correction episodes took place at this time.

To determine the reliability of the researcher’s identification of error correction episodes, a sample of 23% of the recorded sessions was evaluated by a second rater. The second rater was asked to check whether: (1) the error was corrected by the researcher and not by the learners themselves; (2) an error had actually been committed; (3) the error was corrected using one of the three error correction methods; (4) the episode ended with a topic change; and (5) only one error was corrected in each episode.
   The absence of any one of the above criteria in the learners’ utterances would disqualify them from being considered as an error correction episodes. The resulting agreement rate between raters was 88.3%.

3.4.4 Reliability and Validity of the Tailor-made Tests
In the present study, it was not possible to establish reliability using the test-retest method, since every participant had his/her own specific items arising from his/her own errors. it did not seem logical to trial the items from a tailor-made test (i.e. belonging to one person) on other individuals or a different sample group, since every participant had his/her own specific items arising from his/her own errors.
   Therefore, a different approach than the one mentioned above needed to be taken in order to establish the reliability of the tailor-made tests. Basically, all potential threats to the reliability of the tests were addressed. Following Loewen (2002), Brown’s (1996) checklist of potential sources of error variance or measurement error was used.  The checklist points to different potential sources of errors such as environment, administration procedures, examinees, scoring procedures, and test items. For example, in dealing with  the environmental variance, it was obvious that allocating  all the learners to a specific and pre-arranged place where they could read and reconstruct the texts, was very  difficult, because several schools were involved in the study and the participants in each school preferred to be interviewed and tested in their own school. However, the researcher was given a room by each school to carry out the interviews. The rooms had standard facilities like heating and lighting, as well as being quiet the learners were interviewed and tested individually in the rooms. In this study, ways of reducing error variance due to these factors were considered and accommodations to ensure validity were made.

3.5 Procedures
Individualised tailor-made test items, based on the corrected errors in the learners’ reconstructions of the text passages, were administered to the learners individually five to eight days after the time of reconstruction. For the administration of the tests, learners were withdrawn individually to a quiet room where the researcher administered the tailor-made tests (one at a time) to them. They were allowed sufficient time to answer all of the questions.

3.5.1 Scoring Procedures for Definite and Indefinite Article Features

Each learner’s final scores on definite and indefinite article features were a fraction of the correctly answered definite and indefinite test items over the total number of such test items (which varied in every tailor-made test). This fraction was then multiplied by 100 to obtain the percentage of the learner’s score. Since each learner had two tailor-made tests, and therefore, had two scores on the definite item and two scores on indefinite items, the average mean of these two scores was considered to be his/her final score on the definite and indefinite article features.

3.5.2 Scoring Procedures for Regular and Irregular Past Tense Forms

As in the case of definite and indefinite past tense features, the learner’s final scores on regular and irregular past tense forms in his/her two tailor-made tests would be a fraction of the correctly answered regular and irregular test items over the total number of such test items (which were included in every tailor-made test). By multiplying the fraction by 100, the percentage of the learner’s score was obtained. The average mean of the two scores from both of the tailor-made tests was considered to be the mean of learner’s final score on the regular and irregular past tense forms. After the data were collected they were organized and categorized in order to be put into SPSS software for further analysis and the results of which will appear in the following part.

4. Data Analysis and Results
As to the purpose of this study which was to investigate the effect of corrective feedback on the learning and use of the article system and regular and irregular past tense forms in English, two questions were posed. The research questions were formulated as null hypotheses such as: (1) there is no difference between the regular and irregular past tense verb forms in terms of learning and use as a result of corrective feedback; and (2) corrective feedback does not cause any difference between the definite and indefinite articles in terms of learning and use. In order to investigate the above-mentioned null hypotheses, both descriptive and inferential statistics were used; the results of which will be fully described and delineated in the following sections.

4.1. Findings about the Regular and Irregular Past Tense Items

In order to summarize the group characteristics of the scores obtained, first of all, descriptive statistics were computed. As shown in Table 4, the mean score is 78.93 for the scores on the regular tense test items and 85.73 for the scores on the irregular tense test items. The standard deviations for the regular tense and the irregular tense items are 19.64 and 17.04, respectively. Both sets of scores range from 25 to 100.

Table 4: Group Statistics for the Scores on the Regular and Irregular Tense Items

In order to investigate the first null hypothesis, a paired sample t-test was performed to compare the scores on the regular tense items and the scores on the irregular tense items (see Table 5). The output indicated that there was a significant difference in the score means of the regular and irregular test items (t= -2.038, df = 55, p=.046, p< 0.05). This finding indicates that the learners performed more accurately on the irregular past items.

Thus, as a consequence of running a t-test, the first null hypothesis was rejected. That is, corrective feedback affected the learning of the irregular forms more than the regular past tense form.  It is important to know that this finding can only be true for the overall effect of corrective feedback regardless of the effects of each individual treatment on learning. However, as seen in Table 6,the type of treatment that shows to have the most impact on the results is the delayed explicit treatment of irregular form with the mean percentage of 100 (MP= 100%) which is much higher than the mean percentage of the delayed explicit treatment of regular form (M= 72%).

TC= Total Corrections MS= Mean Score MP= Mean Percentage
Table 6: Descriptive Statistics for the Reg/irreg Past Tense Forms

The total valid cases for the definite article test items and indefinite article test items are 56 and 74, respectively. The mean score is 70.53 for the definite article items and 53.57 for the indefinite article items. The standard deviations for the definite article items and the indefinite article items are 17.99 and 16.80, respectively. Scores of both groups of items range from 25 to 100 (See Table 7).

Table 7: Group Statistics for Definite and Indefinite Items

The distribution of scores meets the normality assumption, and therefore, a paired sample t-test was performed. The mean of the scores on the definite article test items was significantly higher than the mean of the indefinite article test items (t = 4.97. df = 55 p=.010, p<.050). Therefore, the learners performed more accurately on definite than indefinite articles.

Table 8: Paired Samples t-Test for Definite and Indefinite Article Scores
The results indicate that the correction of the definite article was more effective than the correction of the indefinite article (Refer to Table 8).

5. Discussion and Conclusions
Overall there were 32 error corrections directed at the irregular past tense verb errors and 43 directed at the regular past tense errors. However, the test score for the irregular was 88% while for the regular past tense it was 78%. A question arises as to why irregular past tense forms are learned before regular past tense forms despite the fact that the fact that the regular form rule applies to more items than does the irregular form (i.e. it has a higher scope); and that, the regular form rule has more reliability. Additionally, the frequency of input is considerably higher for regular than for irregular forms. There may be a number of reasons given as to why irregular verb use precedes regular verb use. Perhaps irregular forms are easier to acquire than the regular form. First, irregular forms occur very frequently in the input because they are among the most commonly used verbs in English [(9 out of 12 of the most common verbs are irregular, according to the Longman Grammar of Spoken and Written English (Biber, Conrad, and Reppen, 1999, p. 375)]. Also, whereas irregular forms involve item learning, a relatively undemanding cognitive process, the acquisition of regular verbs requires the development of the abstract underlying rule (Doughty & Williams, 1998).
   Some other reasons for learners’ better performance on irregular tense verb forms may be such notions as syntactic complexity, perceptual salience, and the novelty of the form in the target language. These are now discussed in order. It is widely established that there are two different processes that account for learning regular and irregular past tense verb forms: (i) A rule-governed process is accountable for appending the tense affix to the verb; (ii) Memorized listing (rote memory) facilitates irregular tense production. This common mental listing capacity, according to Beck (1998), forms the basis for initial performance. Learners initially memorize both regular and irregular tense forms (both regular and irregular are listed in memory). Later on, they abstract out (i.e. make a system ) the ‘ed’ affixation rule which enables them to form the past tense. This stage is accompanied with the overgeneralization of rules (not of concern here). In this period, hypothesis formation and testing take place and learners continually restructure their interlanguage. Finally, learners’ productions of regular past tense verb forms become native speakers like because constraints for ‘ed’ affixation are ‘ready’. However, irregular past tense verb forms continue to stay in memory listing. Klein (1993) argues that this process characterizes the learning of individual lexical items rather than the learning of rules.
Learners are continuously making and testing hypotheses in their language learning. Testing a hypothesis against irregular forms is possibly easier than testing against regular forms, because the abstraction of ‘ed’ takes place after the regular form is listed in memory. Thus, it may take longer for learners to ‘understand’ the form (discussed above) in order to restructure their interlanguage. On the other hand, irregular forms are easier to understand, when reorganizing the interlanguage, than regular forms because learners do not have to abstract out (i.e. make an abstract system) any affixes.
   One reason for the better performance on the irregular forms may be the fact that irregular forms are easier to hear and to perceive than regular forms. Perhaps it is their irregularity that makes them salient. Furthermore, the regular form (ed) is usually unstressed. This also makes the irregular form more salient because it is stressed. However, the case is not straightforward: both regular and irregular forms gain perceptual salience, doing so in different ways. For example, frequency of input for the regular form is higher than it is for the irregular form; this means that the regular forms are also perceptually salient. Therefore, this factor can not be treated as significant. However, a possible consideration to make is, as Gass and Selinker (2001) mention, highly infrequent items can also lead to salience because when an item is infrequent it might get more attention by learners. The number of irregular forms is considerably less than regular forms, thus making them more salient.  Moreover, focus on form in the current study might have increased salience. Thus, correction of irregular forms may have given them a double salient status, which made them more noticeable than regular forms.
   Novelty effect may be another source of the difference between the correction on regular and irregular form use. The native language of the learners in this study was Persian (Farsi); Farsi is an inflectional language. The verbal inflectional system is quite regular and can be obtained by combining prefixes, stems, inflections and auxiliaries. This very complex rule-governed system accounts for regular tense formation, and it does not permit irregular tense forms. Therefore, irregular past tense form in English is considered very different for Iranian English learners. It may be that the presence of the irregular past tense form in English along with salience leads Iranian English learners to notice irregular forms more easily than regular forms.
   Overall, there were 56 corrections directed at definite article errors and 74 directed at indefinite article errors. In other words, learners made more errors with the indefinite article. The overall accuracy score on the tailor-made tests was 72% for the definite article and 56.6% for the indefinite article. The findings in this research show that the correction of errors on the definite article is much more effective than the correction of errors on the indefinite article.
   One reason for the better scores for the definite article may lie in the fact that article systems for definiteness and indefiniteness vary among learners’ native languages; thus, second language learners are more likely to be unfamiliar with the article system in English on a cognitive level because the English article system is novel to them. This is especially true when they are not at an advanced level. The novelty of articles can cause the novelty effect, which leads the learner to notice articles more easily (Gass and Selinker, 2001). Perhaps learners in the present study were able to notice the definite article more easily because their native language (Farsi) requires a different system for definite articles. However, the indefinite article system in Farsi is probably closer to English and this may not have caused novelty effect or stimulated their awareness of this linguistic feature.
   Although the forms and rules of the definite and indefinite articles are uncomplicated, there are certain components of salience that may affect the acquisition of articles. These include frequency, stress, and homonymy. Some of these components are advantageous and some are disadvantageous. The only component of salience that is disadvantageous to the acquisition of the indefinite article is its homonymy with other morphemes. The indefinite article (a) is taken both as a marker for showing singularity of a noun and as an article for showing non-specificity of a noun. Learners may not be able to distinguish these two roles from each other. This homonymy may be why ‘a’ is not as noticed as ‘the’ and, consequently, why correction is not as effective for ‘a’.
   A possible explanation for the fact that the correction of definite article errors was more effective than the correction of indefinite article errors is that the corrective feedback was more effective in helping learners use ‘the’ in noun phrases that had specific reference and were part of the hearer’s knowledge than in helping them use ‘a’ in noun phrases that were non-specific and not part of the hearer’s knowledge. The learners in this study produced article errors associated with mainly two classes of noun phrase contexts. These are:

1. the context in which the noun phrase is referred to specifically and about which the hearer has some knowledge [+ SR + HK], and
2. the context in which the noun phrase is referred to non-specifically (by a speaker) and about which the hearer has no knowledge [- SR -HK].

The correction of errors on [+ SR + HK] class of noun phrase contexts is more effective than the correction of errors on [- SR - HK] class of noun phrase. In other words, the learners may have wrongly associated a different article form (‘a’, ‘an’ or ‘zero’) rather than ‘the’ to [+ SR + HK] class of noun phrase contexts. In which case, providing feedback to help learners associate the right form (the) to [+ SR + HK] is very effective. Conversely, correction of errors on [- SR - HK] noun phrase contexts is less effective than [+ SR + HK]. Correction may not be able to help learners associate [- SR - HK] class of noun phrase contexts to the right article form (a, an).
   A number of other possible explanations can be suggested for this finding. It is possible that definite articles are more perceptually salient than indefinite articles (i.e. ‘a’ may be less salient to learners than ‘the’). It is possible that the findings simply reflect the fact that the definite article is learnt at an earlier stage of development and thus the intermediate level learners in the present study were not fully ready to acquire this feature even when feedback was given on it. It is also possible L1 transfer compounded the learners’ lack of readiness to learn this feature. Also, the indefinite article in Farsi has a very different function from its function in English, whereas the definite article in Farsi has a similar function to its function in English. Therefore, L1 transfer may help explain why lower scores were obtained for items testing the indefinite article.

6. Implications
The findings of this study may carry implications that could be of interest to practitioners in language pedagogy. The most tangible clues of this sort are discussed below.
   As indicated in the finding obtained concerning the learning of the irregular and regular forms, the first implication is that, the same reasons underlying the better learning of irregular forms should perhaps be considered in the teaching of regular forms. In the present study, one reason for better learning of irregular forms was the possibility that learners learned the irregular forms as 'items learning': they most likely internalized such forms by memorizing them. The teacher should perhaps make attempts to avoid linguistic descriptions of regular forms (which involves abstract notions.).The teacher could probably try to contextualise the regular forms that are in need of correction by presenting them in unanalyzed chunks so that they can be learned more optimally through memorization. This would enable the teacher not to interfere so much with the process of abstraction taking place in the learner's interlanguage system.
   In the present study, one reason for less success in learning of the regular forms was the role learners played in abstracting out rules. This would perhaps direct our attention to the second implication from learners' perspectives; in the sense that, instead of using teachers' correction, self-correction is perhaps, in addition to teacher correction, a better alternative for focusing on the correction of regular forms. That is, by doing this, the teacher could involve the learner with the process of hypothesis forming and testing of the correct form.
   Also this study showed that that the saliency of linguistic elements makes them more learnable. Teachers in the course of their instruction should perhaps make the target features salient enough to direct the learners' attention to them. The more prominent a language form at input, the greater the chance it will be noticed.
In the present study, the sequence of learning followed by learners seems to be the definite article first and indefinite articles next. We must take this sequence into consideration in both classroom teaching practices such as error correction and instructional material writing.
   One possible explanation for the fact that the definite article was learned better than the indefinite article was that the latter is taken both as a marker for showing singularity of a noun and as an article for showing non-specificity of a noun. Teachers must try to clarify the double function of the indefinite article as well as the different semantic functions of the English article system for second language learners.

7. Suggestion for Further Research
This study was cross-sectional in nature, affording only a very static view of second language acquisition. No attempt was made to see the effect of correction on errors made by learners at different stages of development. The article issue is so broad and complex that they can not be explained comprehensively and inclusively by a limited study such as the present one. A longitudinal study to investigate error correction on different semantic functions is necessary to further clarify the issue.

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