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If negative feedback can be beneficial for L2 learning, the next question to consider is which features influence its effectiveness. Given Schmidt's (1995) noticing hypothesis, it is argued that learners must notice negative feedback in order for it to be effective. As a result, numerous studies have investigated the salience of different types of feedback. In particular, controversy exists regarding the salience of recasts. On one hand, their implicit and unobtrusive nature does not interrupt the flow of communication, thereby

allowing learners to pay attention to form and meaning at the same time (Long, 1991, 1996, 2007). On the other hand, recasts may go unnoticed because they are not salient enough (Lyster, 2004; Truscott, 1999). Furthermore, the corrective intent of recasts may be ambiguous because of their multiple discoursal functions (e.g., correction, confirmation check, or clarification request) and because teachers often repeat learners’ correct utterances as well as recasting their incorrect ones. As a result, Nicholas et al. (2001) suggest that recasts are most effective when their ambiguity is diminished and their corrective intent is clear. Features that may influence recast salience include prosodic emphasis, intonation, segmentation, number of changes, recast length, and number of recasts (Loewen and Philp, 2006; Sheen, 2006).

In contrast to recasts, elicitations are generally viewed as a more explicit type of feedback, although it may be better to view explicitness as a continuum rather than a dichotomy. Elicitations are generally less ambiguous in their intent, and thus may be more salient as negative evidence. The most explicit type of feedback is explicit correction, and while detractors of explicit correction argue that it can be disruptive to communicative interaction, there is some evidence that more explicit feedback may be more effective for L2 learning (Ellis et al., 2006; Norris and Ortega, 2000).

In an attempt to provide an explanatory statement regarding the salience of feedback, Lyster and Mori (2006) have proposed the counterbalance hypothesis which suggests that feedback will be more effective when it contrasts with a class's predominant communicative orientation. Accordingly, the more communicatively-focused the class, the more explicit the feedback needs to be. This hypothesis is awaiting further investigation.

Another issue in considering the effectiveness of feedback is whether it is effective because it provides positive evidence, negative evidence, or both. On the one hand, negative evidence, indicating that a linguistic construction is not possible, is argued to be a central component of corrective feedback (Long, 2007; White, 1991). On the other hand, positive evidence, consisting of exemplars of what is possible in a language, has also been shown to be an important component of corrective feedback (Leeman, 2003).

The effectiveness of feedback may also be contingent on the linguistic items targeted by that feedback. Any aspect of language can receive feedback, although grammar, vocabulary, and pronunciation are the most common targets in classroom contexts (Ellis et al., 2001; Lyster and Ranta, 1997). In quasi-experimental studies, grammatical structures have been the

primary focus, as can be seen in Table 2.1. Popular targets of inquiry have included English question formation and past tense, while fewer studies have been conducted in other languages or on other features. Furthermore, almost no research has investigated feedback on pragmatics or discourse features.

Table 2.1 Linguistic features targeted in quasi-experimental feedback studies Linguistic

Structure Study

ENGLISH Regular past tense

Adams (2007); Dabaghi and Basturkmen (2009); Doughty and Varela (1998); Ellis (2007); Ellis et al. (2006); Loewen and Erlam (2006); Mackey (2006); McDonough (2007); Nobuyoshi and Ellis (1993); Yang and Lyster (2010)

Past

progressive Révész and Han (2006) Past-tense

conditionals Doughty and Varela (1998) Irregular past

tense Dabaghi and Basturkmen (2009); Yang and Lyster (2010) Tense

consistency Han (2002) Questions

Adams (2007); Loewen and Nabei (2007); Mackey and Philp (1998); Mackey and Silver (2005); Mackey (1999, 2006); McDonough and Mackey (2006); Philp (2003); Spada and Lightbown (1993)

Locatives Adams (2007)

Vocabulary Adams (2007); Alcón and García Mayo (2008); Trofimovitch et al. (2007) Backshifted

verbs Sachs and Suh (2007) Articles Muranoi (2000); Sheen (2007) Definite

article Dabaghi and Basturkmen (2009) Indefinite

article Dabaghi and Basturkmen (2009) Zero article

with abstract Sauro (2009) count nouns

Comparatives Ellis (2007)

Plurals Dabaghi and Basturkmen (2009); Mackey (2006) Relative

clause Dabaghi and Basturkmen (2009) Voice Dabaghi and Basturkmen (2009) Third-

person–s Dabaghi and Basturkmen (2009) Possessive

determiners Ammar and Spada (2006); Ammar (2008); Lyster (2004); Trofimovitch et al. (2007) Multiple,

incidental forms

Havranek (2002); Loewen (2005); Nabei and Swain (2002)

FRENCH Gender marking on articles

Lyster and Izquierdo (2009) Gender marking on nouns Lyster (2004) SPANISH Noun adjective agreement Leeman (2003); Sagarra (2007) Direct object

placement Long et al. (1998) Adverb

placement Long et al. (1998) KOREAN Object relative clauses Jeon (2007) Honorifics Jeon (2007) Verbs Jeon (2007) Nouns Jeon (2007) JAPANESE

Locatives Iwashita (2003); Long et al. (1998) Aspectual –te

i-(ru) Ishida (2004); Iwashita (2003)

Learners’ proficiency levels are also a consideration, with studies suggesting that learners need to be developmentally ready to benefit from feedback (Mackey, 1999; Mackey and Philp, 1998; Trofimovitch et al., 2007). Additionally, there may be an interaction between proficiency and type of feedback. For example, Ammar and Spada (2006) found that higher proficiency students benefited equally from recasts and prompts, while lower proficiency learners benefited more from prompts than recasts.

The timing of feedback is also important. Generally, feedback occurs immediately after an error, and this juxtaposition of incorrect and correct forms is argued to benefit learners (Doughty, 2001; Long, 2007; Saxton, 1997, 2005). However, delayed feedback is also possible, particularly in computer-

mediated communication (CMC) where the nature of synchronous written chat often means that feedback is not contingent to the error (Smith, 2003).

A final potentially influential characteristic of feedback is the amount of feedback provided to the targeted feature. Long's (1991, 1996) original definition of focus on form does not specify the ideal amount of feedback. Indeed, the construct of incidental focus on form (Ellis, 2001; Loewen, 2005) assumes that a linguistic structure may receive only one feedback episode. By contrast, feedback treatments in quasi-experimental studies have ranged from 30 minutes to 120 minutes. In his meta-analysis, Li (2010) found that treatments of 50 minutes or less were significantly more effective than were longer treatments. Additionally, Havranek (2002) found no advantage for correcting the same linguistic error multiple times as opposed to correcting it only once. Further investigations into the effects of the intensity of feedback are needed.

What contextual characteristics of feedback influence