摘 要

听和读是学习者学习语言的主要输入途径之一，现有关于视、听输入模态对外语理解造成的影响并未达成共识，积极的模态效应和负面的冗余效应这两大发现的观点不尽相同。当信息以视听双模态同时呈现时工作记忆的容量会得到有效增加，进而提升学习成效，是为模态效应。但也有学者发现，如果将相同的信息以不同的方式同时呈现会发生冗余效应，从而削弱学习效果。现有研究大多针对一般学习而非语言学习，其结果是否适用于语言学习和外语理解还没有定论。此外，由于外语学习者听读能力的发展具有不平衡性这一特性，输入模态对中国外语学习者理解的具体影响有待深入研究。在梳理现有研究的过程中我们发现，视、听模态的输入长度也很可能是影响理解的一大因素，而现有研究在实验材料的长度方面却鲜有涉及。因此，输入长度对理解的影响成为本研究的另一个焦点。由此，本研究主要试图探讨以下两个问题：
（1）    模态对理解是否有影响；
（2）    输入长度对理解有哪些影响。
   为解决上述两个问题，我们用控制对比实验方法在中国英语学习者中调查了听、听读（字幕）、听读看（视频）三种输入模态下被试的理解效果以及各模态条件下对两种不同长度材料的理解。结果显示，听读看组和听读组的理解效果都好于听组的理解效果，听读等不同模态的结合促进了理解的提高。但考虑到外语学习者听读能力发展的不平衡性，实验结果不能简单归结为模态效应。通过问卷分析，研究发现了有别于前人的新假设——补偿效应，即当外语学习者目的语听觉加工能力较弱时，视觉加工能力可能对听觉加工能力起到补偿作用。此外，被试的理解效果随着材料长度的增加而有所增加，并且对于不同的输入长度，所理解的内容占输入材料的百分比相对稳定，实验证实记忆确有容量限制，但要揭示记忆容量仍需要深入研究。

关键词：输入模态；输入长度；理解
 
Abstract

Listening and reading are two major input resources in second language learning. Currently, explorations into the influence of input modality on comprehension are rather inconclusive. Some have found modality effect, namely, enhanced learning and comprehension through the use of concurrent visual and auditory channels, while others have found a redundancy effect, namely, detrimental effects by identical information simultaneously presented through two channels, which add more working load to the processors. Both of the findings derive mostly from studies in the field of general learning and it has not been determined whether such findings can apply to language learning and comprehension. Moreover, due to the imbalanced development in reading and listening abilities among second language learners, it is not known whether the input modality has influences on comprehension among Chinese learners of English. Additionally, most of the present studies focus on the effects of different modalities on comprehension. A possible influence on comprehension from the length of input has been neglected. At present research is aimed at the following two questions:
1)    Whether input modality influences comprehension;
2)    What influences that length of input has on comprehension.
In order to answer these questions, a controlled comparison study was conducted. First, comprehension under different input modalities was compared: audio, audio plus subtitle, and audio plus subtitle plus images. Then the comprehension under two different input lengths was analyzed to find out whether length of input influences comprehension. The results showed that the audio-subtitle-image group and the audio-subtitle group outperformed the audio group, indicating that a combination of visual and audio input could enhance comprehension. However, a post-treatment questionnaire suggested that due to imbalanced development in reading and listening abilities among second language learners, the results may be evidence of a compensation effect rather than positive modality effect. In a second language acquisition, reading ability may be compensatory when listening ability is relatively weak. Beyond that, subjects comprehended more information as length of input increased. But quite interestingly, our subjects comprehended almost the same amount of input in terms of percentage. It is quite likely that memory has a limited capacity, but it calls for further study to uncover what the capacity is.

Keywords: input modality; length of input; comprehension