Introduction

Feedback has long been regarded as an essential element for the development of second language (L2) writing skills because it both promotes learning and boosts students' motivation (Hyland & Hyland, 2006). However, the effectiveness of written corrective feedback (WCF) in L2 classes has been a heated debate over the last three decades. The starting point for such controversial issues dates back to the mid-1990s when Truscott (1996) confidently asserted that written corrective feedback would not improve learners' writing, which was immediately rebuffed by Ferris (1999, 2004, 2006). Nevertheless, a number of studies were later made to defend written corrective feedback (e.g., Bitchener, 2008; Chandler, 2004, 2009; Ellis et al., 2008) along with various other studies in the field of second language writing and second language acquisition (e.g., Evans et al., 2010; Storch & Wigglesworth, 2010).

Despite all the debates over the effectiveness of written corrective feedback, especially the vehement ones proposed by Truscott (1996, 2009), there is now a growing body of evidence showing the overall benefits of written corrective feedback for the development of students' accuracy (Bitchener & Knoch 2008, 2010; Van Beuningen, 2010).Those who argue for the effectiveness of direct feedback (Chandler, 2003; Ferris & Roberts, 2001; Lee, 1997; Sheen, 2007) maintain that providing learners with the corrected version of their writing would invest time and energy and is more helpful for teachers and students; however, others see the bright side for indirect feedback (Ferris & Helt, 2000; Ferris & Roberts, 2001). 

In spite of the inconclusive findings, a general principle emerging from research is that the choice of strategies and the explicitness of WCF must depend on a number of factors, including the type of error, the nature of the writing task, and the students' proficiency level (Van Beuningen, 2010). The literature is abundant with studies that have explored both teachers' and students' perceptions of WCF (e.g., Ferris & Roberts, 2001; Hyland, 2003; Montgomery & Baker, 2007; Schulz, 2001). However, there are few studies, if any, that have explored teachers' perceptions of EFL learners' written error gravity along with their beliefs about the most effective corrective feedback types to treat them.

The study by Ferris and Roberts (2001), for example, found that unlike indirect feedback, it was direct, explicit feedback that was favored by both students and teachers. They examined the effects of three different types of feedback: coded errors, underlined errors, and no error feedback. Their findings showed that the experimental groups (receiving feedback) had similar performance which was significantly better than the control group (no feedback received). Also, Hyland (2003) found that learners’ response to feedback and the strategies they use may depend on the importance they attribute to the grammatical accuracy of their writing.

Additionally, there are other studies focusing on EFL teachers' beliefs regarding oral feedback, which show teachers’ positive attitudes towards feedback (Mori, 2011; Schulz, 2001). Mori (2011) found that teachers not only focus on enhancing the linguistic ability of their students, but also on ''instill[ing] values such as confidence, independence, and reasonable ability to communicate'' (p. 464). There is a common belief among language teachers that some form of oral feedback is constructive and essential (Roothooft, 2014). Furthermore, Mansourizadeh and Abdullah (2014) compared the impact of oral and written metalinguistic feedback on ESL students’ writing. The result indicated that oral metalinguistic feedback is more effective in improving second language than written metalinguistic feedback. Oral metalinguistic feedback takes less time compared to written metalinguistic feedback because teachers can provide feedback in the form of a mini lesson. They concluded that teachers should apply such feedback more in classrooms as it is much easier to conduct compared with written metalinguistic feedback.

Despite the extensive literature on teachers' attitudes towards corrective feedback, there is a dearth of research on EFL teachers' perceptions toward WCF. Thus, due to the gap observed in this area concerning teachers' preferences, it is essential to understand what teachers perceive when it comes to error types and correction strategies. The present study, therefore, seeks to investigate Iranian EFL teachers' perceptions of the most serious types of written errors made by young adult learners and their preferences for the most effective feedback strategies to treat them. To this end, the study is guided by the following research questions:

1. What are the most serious types of written errors perceived by Iranian EFL teachers?
2. What are the most effective types of written corrective feedback preferred by Iranian EFL teachers?

Review of the Literature

This section reviews the literature relevant to this study with a focus on the theoretical background regarding different types of written corrective feedback and error types. Additionally, a number of empirical studies have been reviewed to present a deeper understanding of the nature and the effectiveness of different types of feedback on various error types.

Global vs. Local Error

 Local errors are the ones that only affect single elements of a sentence (for example, morphological errors), while global errors are errors that drastically affect sentence structure (Ellis & Sheen, 2011). Since global errors affect intelligibility, it has been suggested that teachers pay more attention to the correction of global errors than local errors (Burt & Kiparsky, 1978). Munro and Derwing (1995) define intelligibility as the degree to which the speaker’s intended meaning is understood by a listener. Therefore, intelligibility is an important concept for teachers of English language to the degree that they strive to prepare students to interact effectively in lingua franca contexts (Yazan, 2015). This is related to how native speakers react to non-native speakers' utterances, where native speakers' focus is mainly on meaning rather than on form and they do not react to utterances that do not interfere with communication (Nassaji, 2016).

Celce-Murcia (1991) suggested that it is effective to make a distinction between sentence-level and discourse-level errors, i.e., the errors that the learners commit beyond sentence-level, say within a paragraph. Sentence-level errors are local errors, while discourse-level errors are more global and have to do with familiarity of discourse features and cohesive devices that connect sentences to create coherent discourse (Nassaji, 2016). From another perspective, errors are categorized as either treatable or untreatable (Ferris, 1999). This will be examined below.

Treatable vs. Untreatable Errors

Whether an error is treatable or not depends on the nature of the linguistic feature, specifically whether the feature is ''rule-governed'' or ''rule-based'' (Bitchener, 2012). Treatable errors ''occur in a patterned, rule-governed way'' (Ferris, 1999, p. 6). They include subject-verb agreement, verb tense or form, articles, pronouns, and spelling (Ferris, 2006). Frear (2012) suggested that written corrective feedback helped learners accurately use regular past tense, but not the irregular past tense. As stated by DeKeyser (2016), the complexity of an L2 structure for learners might stem from a myriad of factors including abstractness or novelty in meaning, the number of choices involved in selecting the correct morphemes for each form, and lack of clarity in form-meaning mapping. Thus, errors with verb tense choice (e.g., simple present vs. simple past) can be more treatable than errors that involve an understanding of aspect, which need more novel distinctions for most learners (Ayoun, 2001, 2004; Ishida, 2004). Untreatable errors, on the other hand, are idiosyncratic by nature and, therefore, cannot be treated by a certain set of rules (Ferris, 1999). They are also called item-based features (Bitchener, 2012). Untreatable errors, or item-based features, belong to one of the following categories: word choice, idioms, and sentence structure (Ferris, 2006).

Based on the explanation above, we propose the following typology of errors (see Figure 1).

Figure 1: Typology of students’ errors

Based on this model, errors fall into one of the four categories of (1) local-treatable, (2) global-treatable, (3) local-untreatable, and (4) global-untreatable.

Feedback Types

A variety of different ways in which errors can be corrected have been reported by methodologists and SLA researchers, and the main distinction is between direct, indirect, and metalinguistic correction types (Ellis, 2009a). Although there are inconclusive findings, a general principle is that the choice of strategies and explicitness of WCF depends on a range of factors, including the type of error, students' proficiency level, and the nature of the writing task (Van Beuningen, 2010).

Feedback explicitness can be defined regarding the extent to which feedback provides learners with explicit information about the nature of the error and how learners must deal with them (Nassaji, 2016). Although most often implicit and explicit feedback are regarded as binary categories, feedback explicitness is relative and can be different concerning the amount of explicit information the feedback provides (Nassaji, 2016). Although one cannot agree with the effectiveness of written corrective feedback in general, WCF could be considered to be an appropriate way to be successful in this regard and a wide range of WCF typologies could be found in the literature as well (Bitchener, 2008, 2012; Ferris, 1995, 2004; Hyland & Hyland, 2006; Robb et al., 1986; Sheen, 2007). Depending on the degree of feedback explicitness, feedback can impact learners' awareness at the levels of noticing or understanding, which may play significant roles in how learners process the feedback (Nassaji, 2009, 2016).

Direct Feedback

The main body of WCF research has focused on the effectiveness of various types of feedback depending on the degree of explicitness, that is, whether the feedback offered is direct or indirect (Park et al., 2016). Ferris and Roberts (2001) suggest that direct CF is possibly better than indirect CF with student writers at low levels of proficiency. However, the problem is that it requires minimal processing on the part of the learner and therefore, while it may enable them to generate the correct type as they revise their writing, it does not lead to long-term learning. A study by Sheen (2007), however, indicates that direct CF may be effective in encouraging specific grammatical features to be acquired. Direct feedback includes drawing a line on the erroneous form, adding a missing element, or providing a correct form. Other types of direct feedback involve written meta-linguistic explanation, i.e., providing grammar rules and examples at the end of the student's writing or oral metalinguistic explanation, i.e., providing students with rules and examples through mini-lessons, individual or small-group conferences (Bitchener & Knoch, 2008; Bitchener & Ferris, 2012; Rummel & Bitchener, 2015). Metalinguistic feedback involves offering some kind of explicit explanation to students on the nature of the errors they have made (Ellis, 2009b)). Sheen (2007) compared direct and metalinguistic CF, finding that both were successful in increasing accuracy in the use of articles by students in subsequent writing immediately completed after the CF treatment. Interestingly, in the long term, metalinguistic CF proved to be more successful than direct CF (i.e., in a new piece of writing completed two weeks after the treatment). Similarly, Diab (2015) demonstrated how better outcomes were obtained by those who received direct error correction and metalinguistic feedback than those subjected to only metalinguistic feedback.

 It has been postulated that direct WCF is more likely to raise learners' awareness at the level of noticing compared to indirect WCF, which is less explicit. However, it is possible for WCF to boost the learners’ awareness to the level of understanding more explicitly (e.g., through direct plus metalinguistic explanation) (Bitchener & Knoch, 2010; Shintani & Ellis, 2015; Shintani et al., 2014). Bitchener and Knoch (2010), for example, found that the students in the treatment groups who received different kinds of direct plus metalinguistic feedback outperformed the control groups on all four tests.

Indirect Feedback

Indirect WCF involves teachers’ indicating an error without providing the correct form; students take responsibility to recognize and correct erroneous forms on their own (Mao & Crosthwaite, 2019). While direct WCF refers to providing the correct forms for the students, indirect WCF allows teachers to provide clues (e.g., underlining, circles, and codes) and let students come up with their own correct answers (Lee, 2013). It may be applied in one of these four ways: Writing the number of errors in a specific line in the margin, circling or underlining the error; or using a code to indicate what kind of error it might be and where it has been made (Bitchener & Ferris, 2012; Ferris and Roberts, 2001; Robb et al. 1986; Rummel & Bitchener, 2015). However, Lee (1997) specifically compared the two forms of indirect correction and discovered that learners were better able to correct errors that were indicated and located than errors that were only observed by a marginal check.

Benson and Dekeyser (2019), however, mentioned that if a learner does not have sufficient declarative knowledge, then direct examples of form along with metalinguistic explanation might be required. The effects of two different types of indirect feedback were examined by Ferris and Roberts (2001). i.e., underlining versus underlining and codes, and found no significant difference on accuracy between two types.

Although recent research suggests the efficacy of direct over indirect WCF for longer-term acquisition of target items, there is evidence to show the short-term benefits of both direct and indirect WCF strategies (Bitchener & Ferris, 2012). Likewise, Chandler (2003) observes that direct feedback outweighs indirect feedback. Shintani and Ellis (2014) found a positive impact for metalinguistic explanation; similarly, Shintani et al. (2015) reported an advantage for direct feedback. As Ferris and Hedgcock (2014) stated, direct feedback helps to reduce uncertainty and reduces the cognitive load, which allows learners to confirm their theories more clearly.

 One general point of consensus on the part of the WCF researchers is that the choice of the WCF must rely on a variety of learner-internal variables, such as their first language background (L1) (e.g., Park, 2013), their L2 proficiency (e.g., Bitchener & Knoch, 2010; Ferris, 2004; Hyland, 2003; Hyland & Hyland, 2006; 2013; Van Beuningen, 2010), their previous L2 exposure/learning experiences (Bitchener & Knoch, 2008), differences, such as language analytic ability, and individual differences (Ferris, 2010; Sheen, 2007).

Negotiated Feedback

There is, however, another argument by Nassaji (2011), which suggests that relying merely on unidirectional feedback without any student-teacher interaction would not bring fruitful results. As Nassaji (2011) has argued, ''it is possible that if the feedback is provided in a negotiated and interactive manner, it may become more effective because in such cases the feedback can become more fine-tuned and adjusted to the learner's level of interlanguage through negotiation'' (p.317). There have been many studies confirming favorable impacts for negotiation (e.g., Baleghizadeh, 2015; Ellis et al., 1994; Lyster, 1998, 2002; Nassaji, 2007, 2009; Van den Branden, 1997). Long's (1996) updated model of the interaction hypothesis, which emphasizes that negotiated interaction is an important source of L2 learning, is one of the perspectives in theoretical support for negotiation (Long, 2006, 2015).

 The importance of negotiation is related to the theoretical significance of focusing on form in SLA, as well as the idea that the effectiveness of corrective feedback depends on the degree to which constructive communication in L2 classrooms is integrated (Doughty, 2001; Ellis, 2016; Long & Robinson, 1998).

Another perspective from a socio-cultural framework, includes Vygotskian sociocultural theory (e.g., Aljaafreh & Lantolf, 1994; Lantolf & Thorne, 2006; Macaro, 2010; Nassaji & Swain, 2000). The sociocultural perspective focuses on the social and dialogical nature of feedback in particular. (Aljaafreh & Lantolf, 1994). The efficacy of feedback is largely dependent on the degree of negotiation and meaningful transactions between the student and the instructor (Nassaji & Swain, 2000).

Many studies, however, have investigated negotiation when it comes to oral errors, and only very few studies to date have examined the role of negotiation in addressing written errors in L2. One of these studies was carried out by Aljaafreh and Lantolf (1994); this research examined negotiated feedback from a socio-cultural perspective that occurred in oral interactions between three English writers and one tutor. They operationalized the term negotiated feedback considering it a ''regulatory scale''; it actually consists of different feedback strategies, which begins with implicit feedback and moves gradually to more specific direct and explicit guide in a scaffolding way. The findings revealed that negotiated feedback facilitated the learning of new forms and also enhanced learners' control over forms already established. They indicated that it is through such support that feedback becomes effective and, therefore, can boost the learners' interlanguage development. 

The present study, then, aims to adopt different kinds of feedback proposed by Nassaji (2011) through combining them with the most common types of feedback, namely direct and indirect ones along with their specific concrete approaches mentioned in the literature to have the comprehensive framework with regard to all types of written feedback. Figure 2 is a proposal for various types of feedback.

Figure 2: Typology of feedback strategies

According to this grid, one can conceptualize four major feedback types: (1) direct/non-negotiated, (2) direct/negotiated, (3) indirect/non-negotiated, and (4) indirect/negotiated.

Method

The survey used in this study provided the researchers with an opportunity to generalize information gathered from a sample of EFL teachers to investigate their perceptions of the most serious error types and the most effective types of WCF strategies they preferred. The economy of the survey and the rapid turnaround in data collection allowed the researchers to go for such design (Creswell, 2009).

Participants

The participants of this study were 253 EFL teachers, both males and females, teaching English to young adult learners (aged between 11 to 14) at a foreign language institute in Iran. The proficiency level of the participants was checked through the Oxford Placement Test (OPT), which was found to be at B1 (Threshold level).

 The language institute is one of the largest in the country and has branches in multiple cities. In order to reach out to the potential participants and have a sample representative of the teacher population in the selected context, we utilized cluster sampling technique. According to Best and Kahn (2006), this method of sampling is used ''when the geographic distribution of the individuals is widely scattered'' (p. 18). Since the teachers surveyed were teaching in different branches of the institute this method of sampling was employed.

The participants were selected from 13 different branches of the institute in Iran. The total population of teachers was 1049 in different branches of the institute throughout the whole country. Using Cochran’s formula (1977), we found a sample of 253 teachers would be a suitable representation of the population.

Instruments

The instrument used in the study was a questionnaire developed by the researchers based on the information gathered through an in-depth review of the related literature on the most common errors made by the learners and the most effective WCF types used to treat them (See Appendix 1). Thus, the questionnaire consisted of two main sections with Likert-scale items. The first section comprised 10 items seeking to explore teachers' attitudes toward error gravity, while the second section included 10 items concerning teachers' attitudes about the degree of effectiveness of the strategies used to treat the errors. For the items in the first section, respondents needed to respond the degree of importance regarding error gravity. The responses varied from 1 (the least important ) to 5 (the most important). The second section has a scale ranking from the least effective to the most effective feedback types, wherein 5 is the most effective and 1 is the least effective. The reliability of the questionnaire was examined using test-retest method of estimating reliability (r=.93) which demonstrates an optimal value of consistency over time.

Procedure

In order to construct the items for the first part of the questionnaire (common errors made by the learners), a pilot study was needed to collect an adequate sample of student writings. Thus, about 100 samples of students’ written assignments were analyzed by the first researcher to find the most common errors. Additionally, a number of experienced teachers were also interviewed to seek their opinions about these typical errors as well. The data gathered through this pilot study guided the researchers to develop items for the first part of the questionnaire.

Although designing the items for the second section of the questionnaire (items related to corrective feedback types) required an extensive review of the related literature done by the researchers, the researchers collected further data through interviews with experienced teachers as well to seek their opinions about the corrective feedback strategies that they would often employ in their classes. Once the questionnaire was ready, it was sent out to the 253 EFL teachers participating in the study. Through an online google form survey (google form), the questionnaire was administered to the teachers in the target clusters.

Data Analysis and Results

Table 1 shows the descriptive statistics for the first part of the questionnaire. The first row shows the number the items (10). The second row shows the number of the participants who responded to each item (253). The third and the fourth rows, respectively show the mean score and the standard deviation for each item.

Table 1: Descriptive statistics for the perception of error types

As shown in Table 1, the means of items 1, 2, and 7 were the highest compared with the means of the other items with respect to the most serious errors committed by the learners, with item 1(M= 4.68) receiving the highest level of attention, followed by item 7 (M=4.66), and finally item 2 (M=4.55), respectively. This means that based on the responses given by the 253 teachers in the study, the first and the second items which belong to the category of verb form and verb tense, and the seventh item related to the word order driven by psychological verbs (see Appendix 1, Part A) are the most serious errors that learners commit in their writings. According to Ferris (2011), verb tense and verb form are considered treatable errors; ''It is treatable as the student writer can be pointed to a grammar book or set or rules to resolve the problem'' (Ferris, 2011, p. 36). Although errors of this kind can be treated by the students themselves, simply by checking a grammar book and many other resources, they are the most common and serious ones they make. It seems that even learners of higher proficiency would still commit such errors, as they may not have been fully internalized in lower levels. These two errors are also among local errors that according to Burt (1975), only affect single elements in a sentence, and do not hinder communication, such as errors in noun and verb inflections, articles, auxiliaries and the formation of quantifiers.

The third type of error is item 7, i.e., word order driven by psychological verbs. It is rather different from the other two as it is treatable, yet global. As Burt (1975) observes, ''Many predicates (both verbs and adjectives) tell how a person feels about something or someone. They describe psychological states or reactions towards something or someone, as in:

She loves that color.

He’s glad you’re here.

 Psychological verbs always require (a) the animate being who experiences the feeling, called the experiencer, and (b) the thing or person that causes the feeling to come about, called the stimulus'' (p. 58).

The problem arises when learners use psychological verbs that require reversing the order of experience and stimulus (Burt, 1975). 'When this is not observed, learners make ungrammatical sentences like the following:

#Call your mother—she worries you (you worry her)

#He doesn’t interest that group (That group doesn’t interest him) (Burt, 1975, p. 59).

In the present study, the two error types of local-treatable and global-treatable (cells 1 and 2 in Figure 1) were identified to be the categories wherein two main error types, namely verb form and verb tense, as well as word-order driven by psychological verbs were among the most serious errors made by the learners.

As for the second research question of the study, namely the most effective types of corrective feedback, the findings revealed that items10 and 3 by far received the highest means (M=4.50, and M=4.44), respectively (see Table 2).

Table 2: Descriptive statistics for the most effective feedback type preferred by EFL teachers

Table 2 shows that items 3 (direct/non-negotiated feedback) and 10 (indirect, negotiated feedback) have the highest means (M= 4.44 and M=4.50, respectively) and this suggests that the participants in this study preferred these two feedback types. This means that teachers favor correction strategies that (a) involve negotiation and scaffolding and (b) are direct and accompanied by metalinguistic explanations.

Discussion

Two types of feedback, namely direct/ non-negotiated and indirect/negotiated were found to be the most effective feedback types by the EFL teachers in this study. Additionally, the most serious error types were verb form and verb tense as well as word order driven by psychological verbs from teachers' point of view.

The kind of indirect feedback in this study, however, totally differs from the one discussed in the literature, which is non-negotiated; through providing learners with codes and underling errors, they just notice that they have made mistakes. In this study, on the other hand, the nature of negotiation is of significant importance, which, as Nassaji (2007) rightly observes, involves teachers beginning the feedback episode indirectly and gradually move towards more direct help as needed. Negotiation, as Nassaji (2016) pointed out, is a process that occurs through back and forth interactional strategies, which is used to reach a solution to a problem within the course of communication. That might, therefore, clearly explain why teachers' top priority in this study was giving a more indirect type of feedback along with negotiation to students' errors, as the type of the error for which teachers had to provide feedback, belongs to verb tense. As discussed above, while identifying the most serious error type, the participants selected verb form and verb tense, they might believe that since verb tense would be considered as the one serious error frequently made by the students and should be acted upon immediately, it is better to try to involve students cognitively to have them arrive at the best possible answer to such errors. Although at first it seems pretty much an easy structure, young adult learners in the context of the present study might have made many such mistakes in the class and therefore make teachers more concerned with applying other fruitful strategies to help them internalize that specific form.

Furthermore, the findings of the present study, in relation to negotiation of the feedback, are clearly in line with what Nassaji (2016) asserted when claiming that negotiation of form can occur to negotiate how a language system works and therefore can provide a effective means for promoting metalinguistic understanding about the form–meaning relationship that must be developed for successful language learning.

In this study the second type of feedback, i.e., direct/non-negotiated feedback, which is the exact opposite of the previous one (indirect/ negotiated), also received considerable attention by teachers. This is in harmony with Frear’s (2012) study, which found that written corrective feedback helped learners accurately use regular past tense, but not the irregular past tense. This finding supports the idea that structures that are rule-governed (regular past tense) are more treatable than those for which there are no clear patterns. Thus, that might be one obvious reason why this kind of feedback, along with metalinguistic comment, received the second most considerable attention. Also in line with Sheen’s (2007) finding, she suggested that direct error correction plus written metalinguistic explanation was more effective than direct error correction alone. Ferris (2011) also suggested that students usually benefited more from corrections when followed by metalinguistic explanations, in particular written information.

Contrary to many researchers’ claims, which argue that learners with less language proficiency are not likely to benefit from it because learners need a certain degree of linguistic competence in order to be able to correct their errors themselves (Benson & Dekeyser, 2019; Bitchener & Knoch, 2010; Ferris, 2004; Ferris & Roberts, 2001), the teachers in the present study were of the opinion that indirect/negotiated feedback would be one of the many possible strategies they opted for when it comes to the errors such as verb form and word order driven by psychological verbs made by their students.

As suggested by DeKeyser (2016), the complexity of an L2 structure and the difficulty it presents for learners can stem from many different factors including abstractness or novelty in meaning, the number of choices involved in choosing the correct morphemes for each form, and lack of transparency in form-meaning mapping. Therefore, errors with verb tense choice like the one found in this study (e.g. simple present vs. simple past) may be more treatable than errors which involve an understanding of aspect, which requires more novel distinctions for most learners (e.g. Ayoun, 2001, 2004; Ishida, 2004). Ishida (2004) investigated the short term and long-term effects of intensive recasts on Japanese morphology. The study found the positive role for recasts when they are frequently provided on linguistic forms for which the learners have some previous knowledge. That said, one error type in this study (word order driven by psychological verbs) might bring more difficulties for the learners than verb form and tense, and therefore need more attention when it comes to providing feedback strategies to address them. With all this evidence at hand, it might be safe to say that, due to lack of analytic ability, it would be hard and time-consuming for students to come up with the correct form.

Conclusion

This study was designed to investigate 1) the most serious types of written errors perceived by Iranian EFL teachers and 2) the most effective types of written corrective feedback preferred by them. To answer the first question, the researchers found that, according to teachers' views, verb form and verb tense, as well as word order driven by psychological verbs would be the most prevalent and serious ones that students would have in their writings. Regarding the second research question, the findings of the study revealed that direct/non-negotiated and indirect/negotiated feedback types were the most effective types of feedback to be given to learners. For teachers of this study, treatable items were to receive special attention as it would help young adult learners to come up with the right forms on their own, so that no ambiguities would be left. As for the second research question, based on which teachers felt that negotiation and metalinguistic feedback provision were of high importance, providing young adult learners (who are not considered to be of high level of proficiency) in this study with such feedback would again help them gradually discover the correct form, which is much easier for them to take in.

The findings of the study suggest that, based on the level of proficiency, learners must receive the most tangible type of feedback which is in line with the errors most likely to be committed by them. Teachers need to familiarize themselves with the best possible feedback strategies to apply them in the class to see which one to select based on the complexity of the structures, students' needs, and the requirements of the curriculum in that context.

As for the limitations of the study, the authors could have compared two groups of language proficiency, e.g., advanced learners to find out what teachers think when comparing two groups and what would be the discrepancies in terms of the type of error made by them and the feedback type they have to receive. For this reason, the findings should be interpreted with caution as they may not be generalized and extended to other contexts or errors committed by students at other age groups and language proficiency levels.

Future studies would most probably find more robust findings by doing so, which will bring more significant contributions to studying teachers' beliefs. To add more robust findings to the study, students' opinions throughout a questionnaire could also be included to see if there were any differences between what teachers perceive as to be the most serious error types and also the most reliable strategies to tackle students' problems, as well as what the students think and make of the feedback received. Additionally, experimental studies are needed to explore which error types are sensitive to which corrective strategy. In other words, one needs to design an experimental research to find out which type of corrective strategy is likely to overcome which error type. This is a very important issue because, at the present, there is not enough evidence to show which feedback type (e.g., direct or indirect) works best with which grammatical forms.

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