WMC and Corrective Feedback

From an interactionist perspective, a few studies have attempted to elucidate the role of WMC in facilitating noticing of CF. Mackey, Philp, Egi, Fujii, and Tatsumi (2002) investigated the extent to which WMC is related to noticing recasts that target errors in question formation, and whether this relationship is associated with learners’ developmental level. The study showed that participants with smaller WMC were more likely to report less noticing during stimulated recalls in comparison to those with larger WMC. However, the relationship between noticing and WMC was only marginally significant. The study also indicated that learners with high PSTM reported greater noticing, but mainly at lower developmental stages. Nevertheless, the researchers warn that due to the small number of participants, these findings should be interpreted with caution and more research is needed. In

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a more recent study, Mackey, Adams, Stafford, and Winke (2010) explored the relationship between learners’ WMC and the amount of modified output they produced. The researchers demonstrated a positive relationship between WMC and output modification. That is, learners with larger WMC produced a greater amount of modified output than those who achieved lower scores on a WMC test. Nonetheless, it should be noted that due to the low effect sizes (under 20%), the researchers suggested that output modification might be associated with other variables as well, apart from WM.

Considering that modified output is not a reliable predictor of subsequent improvement (see section 2.1.4), researchers have also utilized a pre-test, post-test and delayed posttest design to illuminate whether the effectiveness of CF in terms of promoting L2 gains is influenced by learners’ WMC. Mackey and Sachs (2012) examined the relationship between WMC and L2 development of nine older learners whose ages varied from 65 to 89. The learners received interactional feedback targeting errors in question forms while performing communicative tasks. The researchers found that only the central executive played an important role in immediate L2 benefits. With regard to delayed posttests administered both a week and a month after the treatment, no relationship was found between the learners’ improved performance and any of the components of WMC.

In a similar vein, Révész (2012) explored whether PSTM and complex WMC are associated with potential positive effects of recasts on

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development of the past progressive across different outcome measures. L2 development was gauged by a pre-test and a post-test that consisted of a grammaticality judgement task, a written picture description task and an oral description task. The study revealed that recasts were effective in leading to second language learning; however, complex WMC was linked to L2 benefits on the written tests (i.e. a grammaticality judgement and written picture description test), while greater PSTM was related to improvement on the oral test.

Goo (2012) obtained similar findings to Révész (2012). Goo examined the relationship between WMC and the effectiveness of recasts and metalinguistic feedback in promoting development in the knowledge of the English that-trace filter. L2 development was assessed by two outcome measures: a grammaticality judgement test and a written production test. The study found that although the two types of feedback were equally effective on both tests, the L2 benefits demonstrated by the recast group on the grammaticality judgement test and the written production test were mediated by their WMC. In other words, learners with larger WMC benefitted from recasts to a greater degree than their counterparts with smaller WMC. Hence, in both Révész (2012) and Goo (2012), the central executive affected the extent to which recasts facilitated L2 gains exhibited on written tests. Nevertheless, in a more recent laboratory study that was a conceptual replication of Goo’s (2012) quasi-experimental study, Goo (2016) demonstrated that WMC was associated with the benefits of neither metalinguistic feedback nor recasts (see Table 1). Unlike his earlier study,

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Goo (2016) employed an oral production test rather than a written one, and feedback was provided during a dyadic interactional task. Goo (2016) concluded that providing recasts during dyadic interaction in a laboratory setting benefits learners, irrespective of their WMC.

Yilmaz (2013) also offers interesting insights regarding the relationship of implicit and explicit feedback with WMC. In particular, Yilmaz investigated the efficacy of explicit correction and recasts in assisting the acquisition of two Turkish constructions: the plural morpheme and the locative case morpheme, and the role of WMC. The participants were native speakers of English and L2 learners of Turkish; however, they had no previous exposure to the L2 prior to the study. Learners’ emerging knowledge of the target features was assessed by an oral production, a comprehension and a recognition test. A delayed post-test with the same tasks was employed two weeks later. Similar to Goo (2016), Yilmaz (2013) found no relationship between WMC and knowledge of either the plural or the locative under the recast condition. On the contrary, unlike Goo (2012, 2016), in Yilmaz’s study, WMC moderated the degree to which the learners benefited from explicit correction targeting either the plural or the locative. However, a comparison between Yilmaz’s and Goo’s studies should be made with caution. In Yilmaz (2013), the participants had no exposure to the L2 prior to the study, whereas in Goo (2012, 2016) the learners were familiar with the L2. The rationale for why this difference might be crucial is that when an experiment is conducted in a context familiar to the participants’ linguistic system, information stored in LTM with respect to the second language (e.g.

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moprhosyntax, phonology etc.) may assist in the processing of more implicit feedback in WM. In contrast, the processing demands of completely novel linguistic items in an unfamiliar L2 involve the creation of new representations; consequently, more explicit interventions may be needed for large WMC to contribute, as in Yilmaz (2013).

Previous findings have also indicated a relationship between WMC and sustained L2 gains. In particular, a few studies have shown that the effect of WMC on the efficacy of recasts in facilitating L2 development was revealed in a delayed post-test rather than an immediate one (Mackey et al., 2002; Trofimovich, et al., 2007). In Mackey et al. (2002) the participants received recasts on question formation and their L2 development was measured by a pre-test, an immediate post-test and a delayed post-test composed of communicative tasks. The study demonstrated that students with high WM scores achieved greater L2 development than those with lower WM scores; however, this difference was only found in a delayed posttest. Likewise, Trofimovich et al. (2007) found that their participants’ phonological memory influenced the benefits of morphosyntactic recasts, though this relationship was revealed only in a delayed post-test. Therefore, the findings of these studies suggest that WM might not affect L2 learning immediately after treatment but rather in the long run.

Regarding computer-delivered feedback in the form of oral recasts, Sagarra (2007a) noted that learners with higher WM spans produced more modified output and they exhibited greater gains related to accuracy than

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low WMC learners. Additionally, in a more recent study, Sagarra and Abbuhl (2013) showed that the extent to which computer-delivered recasts are influenced by WMC is associated with whether they are oral or written. In particular, Sagarra and Abbuhl found a positive relationship between WMC and the efficacy of both enhanced and unenhanced computer-delivered oral recasts, while WMC did not affect computer-delivered typographically enhanced and unenhanced written recasts. This finding is in line with Payne and Whitney (2002), who observed that WMC influenced oral FTF interaction to a greater extent in comparison to interaction combining both modes (oral FTF and written SCMC). However, it should be noted that, in Sagarra and Abbuhl (2013), recasts were provided for sentences that were not part of meaningful interaction. Hence, their focus was not on SCMC. In future, more studies are needed to delve into the impact of WMC on feedback supplied as part of meaningful interaction in both SCMC and FTF modes.

With respect to TBLT, an under-researched area is the effects of task complexity on the efficacy of CF and the role of WMC as a moderating variable. A study that has attempted to shed light on this issue is Kim, Payant, and Pearson (2015). The researchers explored the degree to which task complexity with differential reasoning demands affected (1) noticing of recasts on non-targetlike English question constructions, (2) development in the knowledge of a target feature and (3) whether these relationships are influenced by WMC. The study was conducted in a laboratory and required the participants to perform three two-way information-gap tasks with a

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native speaker. The two experimental groups differed as to whether they carried out simple or complex tasks. In the simple condition, the learners had to exchange information, whereas in the complex condition, they were asked to exchange information, and additionally to make comparisons and evaluate information in order to make a decision and reach a consensus. The learners in both conditions received a recast in response to non-targetlike questions. The construct of task complexity was validated by utilizing stimulated recalls immediately after the third treatment, during which the participants were presented with a video showing the treatment sessions and asked to report their thoughts during the interaction. The noticing of recasts was measured by using immediate cued recalls; inaccurate production of question formation was followed by a recast and the researcher knocking twice, thus prompting the learner to repeat the preceding utterance, i.e. the recast. L2 development was assessed by a pretest, posttest and delayed posttest that consisted of three oral production tasks.

The study found that regardless of task complexity, both groups recalled about 80 per cent of the recasts accurately in immediate cued recalls; however, WMC influenced their ability to notice recasts and repeat them correctly. Specifically, learners with larger WMC noticed feedback to a greater degree than their counterparts. A similar pattern was found for recasts on advanced question forms (stages 4 and 5). In particular, the learners in both conditions (simple and complex) accurately recalled about 78–79 per cent of recasts; however, the learners’ WM predicted the extent

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to which the participants successfully noticed feedback. With respect to the development of question formation, the study demonstrated that learners with larger WMC benefited more from recasts than their low WMC peers, especially under the complex condition.

2.4.3 Summary

In summary, previous research has provided evidence that both the central executive and PSTM influence several areas of second language development, such as the acquisition of vocabulary and grammar, L2 comprehension and production. Previous studies also indicate that WMC is associated with the extent to which different types of CF facilitate the noticing and learning of linguistic targets. Apart from WMC, researchers interested in individual differences in SLA have also examined the role of L2 aptitude in learning outcomes. The following section first presents a theoretical review of L2 aptitude, and second studies that have investigated the relationship of L2 aptitude (1) with learners' ultimate attainment, (2) implicit and explicit instruction and (3) different types of CF.