The Effects Of Output Task-Types On L2 Lexical Acquisition

In proposing the Output Hypothesis,Swain(1993,1995,1998,2005)claims that output,under certain circumstances,may prompt learners to perceive their linguistic deficiency and bring to their attention the formal features they want to learn.While promising,empirical work on this noticing function of output has been limited and inconclusive.The mixed results indicate that output does not necessarily trigger the cognitive mechanism conducive to language acquisition.What remains unclear is the condition under which output can serve as a priming device to facilitate language development.Driven by the need for such information,this research attempted to identify some constraints and potentials for learning created by output processing.Research has shown that the efficacy of output may depend mainly on such factors as task types,linguistic features,and L2 proficiency.However,little is known about how these factors individually and together affect learners’ attention to linguistic forms and their acquisition.This research aimed at addressing the issue by examining the effects of different types of output tasks on the noticing and acquisition of L2 lexical items(including more salient single words and less salient formulaic sequences),and whether L2 proficiency would mediate task-type effects.The research consisted of two studies.Study One examined the relative efficacy of output task-types,as compared to a non-output task,in promoting immediate and delayed gains of different types and aspects of lexical knowledge by adult learners at different levels of L2 proficiency.Study Two,by mainly examining the concurrent think-aloud protocols,allowed in-depth and multi-faceted explorations into the noticing processes involved across different stages of the tasks.A total of 327 Chinese students,enrolled in college English classes at two proficiency levels,took part in Study One.The students at the same level were randomly assigned to a comparison group and four experimental groups(EGs),namely,a guided essay-writing group,a reconstruction group,a back-translation group and an enhanced retelling group.After being exposed to the same input material,the EGs were given opportunities for written output whereas the comparison group was asked to perform input-based activities.The four output tasks differed mainly in the degree to which they were focused,that is,the extent to which they required or promoted the use of the particular linguistic forms,thus triggering different amounts and levels of noticing on the part of learners.The task was followed by the second exposure to the same input material.The participants’ noticing and acquisition of the target lexical items were examined by a retrospective questionnaire survey,stimulated recall interviews and vocabulary posttests.Study Two involved ten students similar to those of Study One from the same levels in the same university.They were asked to speak out loud whatever went into their minds while performing the same tasks adopted in Study One.The quantitative and qualitative analyses of the triangulated data yielded the following major findings:1.Different types of tasks had significantly differential effects on the acquisition of lexical knowledge in general.The pattern emerging from the results showed that the more focused output tasks were,in general,superior to the less focused ones in promoting the overall lexical acquisition,a conclusion that lent support to the Output Hypothesis.Task-type effects on lexical acquisition changed differently over time.Although all the task performers suffered a significant drop in scores from the immediate to the delayed posttests,the rates of decline varied among those who performed different tasks,indicating that task-types had statistically differential effects on the rate of forgetting.Specifically,the three focused output groups experienced a more dramatic drop than both the unfocused output group and the input-only group.Learners’ L2 proficiency did not mediate task-type effects on lexical acquisition.Higher-level learners would always gain and retain significantly more lexical knowledge than their lower-level counterparts who performed the same task.2.Somewhat different patterns emerged for task-type effects on the acquisition of single words and formulaic sequences.The findings indicate that while output could promote the acquisition of single words,it did not necessarily work well with formulaic sequences.Only the focused output tasks could facilitate the gains in formulaic sequences.The more focused an output task was,the more likely it would promote the acquisition of sequences,but not necessarily single words.Given that the former were generally less salient than the latter,it could be reasonably argued that a more focused output task would act more favorably on less salient lexical items.The results further revealed that different types of word knowledge required different types of output tasks to promote their acquisition.In terms of the acquisition of receptive word knowledge,the results confirmed the Output Hypothesis and further revealed that the obvious differences between the unfocused and the focused output tasks only lay in their impacts on the acquisition of receptive collocation knowledge,but not receptive knowledge of form and meaning.In terms of the acquisition of productive word knowledge,the results only partially supported the hypothesis in that only the focused output tasks could promote the gains in productive knowledge,particularly collocation knowledge.3.Task-types had a great impact on learners’ noticing of lexical items across different stages of the tasks except Stage 1(i.e.,the first exposure to input).The substantial difference among the five tasks in both the quantity and more importantly the quality of noticing led to a correspondingly significant difference in the frequency and accuracy of lexical incorporation in learners’ writing.These findings revealed the complex nature of output as a cognitive tool in language acquisition.The results suggest that output was selectively facilitative to lexical acquisition,mainly depending on the characteristics of tasks in which learners were engaged and the nature of the lexical items to be learned or the aspects of lexical knowledge in question.The more focused an output task was,the more likely it would promote both the quantity and quality of noticing of certain features of lexical items.However,whether the difference in the noticing processes would lead to a significant difference in learning outcomes largely depended on the saliency of lexical features.The findings contribute to the existing theory by identifying some psycholinguistic contingencies under which output is able to trigger a chain of cognitive processes that result ultimately in the acquisition of single words and formulaic sequences.The results will allow for predictions that help instructors,adult language learners,and materials developers design and choose the types of output tasks that best serve their needs.