Vocabulary acquisition is an important aspect of the second language acquisition. No matter how well the student learns the grammar, no matter how successfully the sounds of L2 are mastered, without words to express a wide range of meanings, communication in L2 just cannot happen in any meaningful way. However the second language vocabulary acquisition has been very largely neglected by recent developments in research and most learners identify the acquisition of vocabulary as their greatest single source of problems. Here the author reviews the factors on the second language vocabulary acquisition and calls for our attention to it.
Key words: the second language, vocabulary acquisition, factors on acquisition
It is widely recognizable that the mastery of vocabulary is an essential component of second language and foreign language learning. It plays a vital role in all aspects of language learning, including listening speaking, reading, writing and translation. Therefore, learners must learn vocabulary well in order to become proficient in L2 acquisition.
Although learners are aware of the importance of vocabulary acquisition in English learning, their effort made to learn vocabulary often result in disappointment and frustration. Learners themselves readily admit that they experience considerable difficulty with vocabulary learning, especially when they have got over the initial stages of acquiring their second language. This draws our attention to the complex nature of vocabulary acquisition and the factors on the second language vocabulary acquisition.
1. Affective factors on L2 vocabulary acquisition
Since 1970s, researchers’ focus has made the transition from aptitude to attitude, from a matter of intellectual to affective aspects, from learners’ ability to their personality. Attention to learners’ learning attitude is significant. Attitudes to learning and the perceptions (and beliefs) that determine them may have a profound influence on learning behavior and on learning outcomes, since successful learners develop insightful beliefs about language learning processes, their own abilities and the use of effective learning strategies, which have a facilitative effect on learning. These learners tend to develop a more active and autonomous attitude that allows them to take charge of their learning. On the other hand, mistaken or uninformed beliefs about language learning may lead to dependence on less effective strategies, resulting in indifference toward learning, poor cognitive performance, classroom anxiety and a negative attitude to autonomy.
SLA theory leaves no doubt about the crucial importance of a further affective variable, motivation, which is actually a cluster of factors that “energize behavior and give it direction” (Hilgard, Atkinson & Atkinson, 1979:281). Chomsky (1988:181) points out the importance of activating learners’ motivation: “The truth of the matter is that about 99 percent of teaching is making the students feel interested in the material”. Motivation involves the learners’ reason for attempting to acquire the L2, but precisely what creates motivation is the crux of the matter, without which even “gifted” individuals cannot accomplish long-term goals, whatever the curricula and whoever the teacher. Thus the concept of language learning motivation has become central to a number of theories of SLA, and motivation has been widely accepted by teachers and researchers as one of the key factors influencing the rate and success of L2 learning, often compensating for deficiencies in language aptitude and learning (Tremblay & Gardner, 1995:505).
In the field of SLA, Gardner & Lambert (1976:199) pioneered work on motivation, proposing an integrative-instrumental duality, which became widely accepted aril confirmed by a number of studies. Their ten year-long research program in which they found that success in language attainment was dependent on the learners’ affective reactions toward the target linguistic-cultural group (in addition to aptitude) gave validity to the study of motivation in SLA though some investigations did not support the model, either by not producing a strong integrative factor, or by coming up with insignificant or contradictory results.
Strength of motivation serves as a powerful predictor of L2 achievement, but may itself by the result of previous learning experiences. Learners with either integrative or instrumental motivation, or a mixture of both, will manifest greater effort and perseverance in learning. Other internal sources of motivation, such as self-confidence, may be more important than either type of motivation in some contexts. Motivation can also take the form of intrinsic interest in specific learning activities and, as such, may be more easily influenced by teachers than goal-directed motivation (Ellis, 1999:523).
1.3 Other individual affective factors
Besides abovementioned affective factors influencing SLA, there are some others, just as inhibition, empathy, tolerance of ambiguity and so on. Inhibition is a kind of affect similar to anxiety. Inhibition develops when we gradually form self-image, which is a kind of awareness of identifying a self that is distinct from others.
With the greater awareness comes the need to protect ego, if necessary by avoiding whatever might threaten the self. Strong criticism and ridiculous words can greatly weaken the ego and the weaker the ego, the higher the walls of inhibition. Empathy is the process of ‘putting yourself into someone else’s shoes (Brown, 2002:143) ’.
Arnold and Brown define the term (Arnold, 2000:19): one need not abandon one’s own way of feeling or understanding, nor even agree with the position of the other. It is simply an appreciation, possibly in a detached manner, of the identity of another individual or culture. It is closely related to cultural relativity, which frees us from our conditioning and helps us recognize that our way is not only way and possibly not even the best way. Learners who are good at empathy are ready to cooperate with others. They can benefit from group work and they can communicate with their partners and learn from them. They are interested in the different culture and can accept their value and life attitude. When learning they will think about the purpose of teaching arrangement, so they are glad to do what the teacher demands them.
However, Learners who are not good at empathy sometimes show passive attitudes towards the teachers’ arrangement. They cannot participate in the classroom actively or they cannot finish their homework according to the teacher’s requirement.
Tolerance of ambiguity, according to Ehrman (Ehrman, 2000:75), can be viewed as made up of three levels of function: intake: letting it in; tolerance of ambiguity proper: accepting contradictions and incomplete information; accommodation: making distinctions, setting priorities, restructuring cognitive schemata.
All of aforesaid researches on affective factors will be taken as the references to make the new categorization and present the operational definitions of affective variables in vocabulary acquisition.
What kind of affective conditions the learners are in is obviously of crucial importance in accounting for individual differences in learning outcome. Learners’ affective states tend to be volatile, affecting not only overall progress but also responses to particular learning activities on a day-to-day and even moment-on-moment basis. Studies in the naturalistic research tradition may prove most effective in exploring how these transitional states are brought about and what effect they have on learning (Ellis, 1999:483).
The effect of affective factors on SLA is interwoven and very complicated. All the variables are related to one another in certain ways, just as anxiety can be connected with plummeting motivation, negative attitudes, and inhibition. Learning attitude is often affected by motivation. In reality, all these factors may result with various kinds of combination among different people. One factor sometimes does not definitely predict or entail another.
2 Learning mode factors on vocabulary acquisition
2.1 Intentional and Incidental Vocabulary Learning
Research on vocabulary acquisition in general, and in incidental vocabulary acquisition in particular, has increased largely over the past years. The concept of incidental vocabulary acquisition first appeared in Nagy and Herman’s research on children’s L1 vocabulary acquisition (Cited in Zhu , 2004). Swanborn and De Glopper  (1999) define incidental vocabulary learning as the incidental, as opposed to intentional, derivation and learning of new word meanings by subjects reading under reading circumstances that are familiar to them. The word incidental implies that the purpose for reading does not specifically provoke learning or directing attention to the meaning of unknown words. Wesche and Paribakht  (1999) believe that such learning is referred to as incidental in that learners are focused on comprehending meaning rather than on the explicit goal of learning new words. Qian  (2002) defines incidental vocabulary acquisition as learners’ vocabulary learning based on the reading purpose of text comprehension.
2.2 Direct and Indirect Vocabulary Learning
Students learn vocabulary indirectly when they hear and see words used in many different contexts, for example, through conversations with others, through reading extensively on their own, especially for children, they learn the meanings of most words indirectly, through everyday experiences with oral and written language.
Students learn vocabulary directly when they are explicitly taught both individual words and word-learning strategies. The scientific research on vocabulary instruction reveals that most vocabulary is learned indirectly and some vocabulary must be taught directly. Direct instruction helps students learn difficult words and direct instruction of vocabulary relevant to a given text leads to a better reading comprehension.
In Nation’s view  (1990), direct vocabulary learning and indirect vocabulary learning are two approaches to vocabulary learning. He holds that, in direct vocabulary learning, the learners do exercises and activities that focus their attention on vocabulary. Such exercises include word-building exercises, guessing words from context, learning words in lists, and vocabulary games. In indirect vocabulary learning, the learners’ attention is focused on some other feature, usually the message that is conveyed by a speaker or writer. And considerable vocabulary learning can occur if the amount of unknown vocabulary is low.
2.3 Explicit and Implicit Vocabulary Learning
In both L1 and L2 lexical teaching/learning there are two main processes of vocabulary acquisition: explicit learning through the focused study of words and expressions, implicit learning through exposure when attention is focused on the use of language rather than learning. Ellis  (1997) defined implicit learning as “acquisition of knowledge about the underlying structure of a complex stimulus environment by a process which takes place naturally, simply and without conscious operation”, while explicit learning is said to be characterized by “more conscious operation where the individual makes and tests hypotheses in a search for structure” (cited in Laufer and Hulstijn , 2001).
Over the past years, researchers have devoted a great deal of time and effort to the development of strategies for explicit vocabulary learning and instruction. There are also some studies which find that both explicit and implicit processes take place in vocabulary acquisition. Ellis  (1997) claims that the perceptual aspects of new words, i.e. acquiring their phonetic and phonological features, are learned implicitly as a result of frequent exposure. And the articulation of word forms develops implicitly as a result of practice. However, the meaning of words is learned explicitly, requiring the conscious processing at the semantic and conceptual levels and paying attention to the form-meaning connections. Krashen  (1981) allows that both explicit and implicit learning take place, but denies that explicit, conscious learning can be converted into acquisition. Ellis and Schmidt believe that explicit knowledge plays an important role in second language acquisition.
It should be pointed out that the notions of explicit and implicit learning should not be confused with the notions of intentional and incidental learning, as discussed in the previous section. Implicit learning can be incidental only, but explicit learning can occur both intentionally and incidentally.
3 Learning strategy factors on vocabulary acquisition
3.1 Studies on Vocabulary Learning Strategies in China
A great number of researches have taken place concerning vocabulary learning strategies since 1990s in China.
Gu and Johnson (1996) provided a general picture of vocabulary learning strategies used by Chinese college students. They conducted a survey with 850 sophomore non-English majors from Beijing Normal University in order to find out the vocabulary learning strategies adopted by them and the relationship between their strategy use and language proficiency. It was found that Chinese college students generally used more meaning-oriented strategies than memorization strategies that were considered as the most popular vocabulary learning strategies among Asian learners. It also concluded that Chinese college English learners employed a wide range of strategies, such as dictionary use, guessing, repetition, and note-taking strategies.
Wu Xia and Wang Qiang (1998) adopted O'Malley and Chamot’s classification and investigated vocabulary learning strategies used by non-English majors in Beijing Normal University. This study revealed that Chinese college students employed a variety of strategies including cognitive and metacognitive strategies in their vocabulary learning; vocabulary learning strategies were closely related to both the quantity and quality of their knowledge of English. Further more, there existed significant differences in the use of vocabulary learning strategies between successful learners and less successful ones.
Zhang Ping (2001) studied the vocabulary learning strategies used by non-English major postgraduate students and found that all the four strategies at metacognitive dimension and eight strategies at cognitive dimension were closely related to the general academic English vocabulary learning while three of four strategies at metacognitive dimension and five of eight strategies at cognitive dimension were closely related to the professional English vocabulary learning.
Chen Hua and Zhang Yifang (2001) studied 225 subjects, including 22 kindergarten children， 211 elementary pupils and 22 junior middle school students. The results revealed that all the subjects had used memorization strategies. Some of them depended on the meaning while others depended on pronunciation. Compared with college students, these younger learners seldom used metacognitive strategies.
Generally speaking, compared with other learning strategies, studies on vocabulary learning strategies are relatively comprehensive. But some problems still exist. Few studies concentrate on the relationship between vocabulary Teaming strategies and individual learner differences, particularly on gender differences.
4 Teaching strategy factors on vocabulary acquisition
Psychologists widely view that there are two types of memory: short-tem memory and long-term memory. The retention of a word relies on both types of memory.
Learners can remember the word either shortly or long time after the—instruction of the word. Gins and Redman suggest that information stored in the memory falls into disuse unless it is activated regularly, in other words, we need to practice what we learn otherwise the new input will gradually fade in the memory and ultimately disappear.
Therefore for language teachers, the main aim is to ensure that what is taught in classrooms can be effectively stored in learners' memory. That suggests that it is vitally important for language teachers to master these memory theories of vocabulary acquisition in order to facilitate learners' foreign language vocabulary learning.
«Then it is necessary that we provide meaningful opportunities in classroom for students to practice what they have learned if memory traces do gradually fade in the memory without regular practice» (Gairns and Redman 1998). Therefore, meaningful tasks in the classroom are required for learners to analyze and develop language at a deeper level, which facilitate their information stored in long-term memory. Task-based language teaching provides opportunities to facilitate the learners' memory of foreign language vocabulary. Moreover the various tasks can motivate the students and arouse their interest that causes them to pay their close attention to their vocabulary learning so that they can learn more effectively.
Knowing a word is more than its meanings or connotations as well as its pragmatic functions. This paved the way for task-based vocabulary teaching, because it provides the language learners with lots of opportunities of participation and negotiation. Learners cooperate with partners or peers to perform tasks by putting vocabulary into meaningful use. Thus they feel confident and are highly motivated because they can get help from teacher or other learners while performing tasks with foreign language vocabulary of higher level. Moreover; learners can be aware of their inefficiencies in language output when performing tasks. In this way, learners continually retrieve and strengthen the vocabulary they have learned by putting them into practical use in task-based language classroom. In a word, task-based vocabulary teaching can effectively facilitate learners' short-term and long-term of vocabulary acquisition.
For learners of English in China, the classroom is usually the only place where students can communicate in the target Language and acquire real experiences using the language. Providing natural contexts in classroom is therefore very important for learners of English to use the language. Moreover, in natural classroom, students are promoted to produce output while performing tasks in spite of their lack of language knowledge. They are encouraged to try to make themselves understood by putting foreign language into practical use. Moreover, the interaction in task-based classroom instruction pushes learners to produce more accurate and appropriate language knowledge, which at the same time provides input to other learners. This is one reason why pair work and group work has become common feature of contemporary classrooms.
In the retention of vocabulary, the psychological research into foreign language acquisition shows that cognitively oriented instruction is more suitable. For short-term recall, mimetic and repetition exercises can be used profitably. But for long-term storage and retrieval, meaningful learning tasks should be involved.
In the recent years, although there are many studies and researches about the theories of the L2 vocabulary acquisition have been done. But the present condition is that the single factor research is still more than the multiple factors analysis after so many years of the second language vocabulary acquisition. And these researches are more theoretical than experimental.
With the development of the theories of L2 vocabulary acquisition, the theory about the second language vocabulary acquisition flourished too. Facing so many theories, for the subject of study, how these theories affected the different levels of students and in what extend? How did the different factors impact the different levels of students? In the study of these questions, it’s still that single factor research was more than the multiple factors analysis after so many years of the second language vocabulary acquisition study. And these researches are more theoretical than experimental. In the future we should focus on the different impacts that the different factors have on the English learners and study these factors as a whole on the basis of experiments. So we can guide the learners' development in second language vocabulary acquisition and enhance the language teaching quality.
- Hulstijn,J. H.Incidental and intentional learning. The handbook of second language acquisition. 2003
- Knight,S.Dictionary use while reading: the effects on comprehension and vocabulary acquisition for students of different verbal abilities. Modern Language Quarterly. 1994
- Laufer B,Hulstijn J.Incidental vocabulary acquisition in a second language: The construct of task-induced involvement. Applied Linguistics. 2001
- Lewis M.Pedagogical implications of the lexical approach. Second Language Vocabulary Acquisition. 1997
- Nagy W.E,Herman P. A. Breadth and depth of vocabulary knowledge: Implications for acquisition and instruction. The Nature of Vocabulary Acquisition. 1987
- Read J.Research in teaching vocabulary. Annual Review of Applied Linguistic. 2004