Abstract：Children can acquire knowledge of their mother tongue easily in a relatively short time， whereas adults are too inferior to bear the comparison in learning a second language. This paper sets out to study the background and process of children’s and adults’ language learning， make comparison and contrast， and find out an effective way to promote adults’ second language learning.

Key words：children’s language acquisition adults’ foreign language learning lexical processing

Ⅰ.Introduction

As depicted by Gleason and Ratner， though born completely without language， children typically have acquired thousands of lexical items， complex phonological systems， basic grammatical structures as well as conventional rules for using their language appropriately by the time they are three or four years old. In contrast to the rapid and efficient language acquisition by children， adults' foreign language learning， though also a developmental process， seems to be slow and laborious. After years of learning， their language is still a long way off perfection. They fail to perform like native speakers either because of their poor phonological performance or because of factors like limited target language vocabulary. In this paper， a micro study of the processes of the lexical learning in children's language acquisition and adults' foreign language learning is conducted， which aims to find out an effective way to promote adults' foreign language learning.

Ⅱ.The Steps in Children’s Word Acquisition

In general， children’s word acquisition often includes the following 3 steps.

1. Encountering new words

Attention and cognitive readiness are two essential conditions which help a child in his word acquisition. New words occur to a child's working memory only when his attention is drawn by them and his cognitive ability is ready for learning them . As Slobin reported， when asking a child questions with difficult words or syntax， which are out of his reach， the child will shift attention and give a nonsense answer. In many Psychological experiments， scientists also found that a child might refuse to notice new lexical information when his cognitive level hinders him to comprehend it. When encountering new words， children might process them further， or not process them at all.

2.Segmenting the form and creating the potential meaning

With no word knowledge existing in mind， a child seems to get the word form by segmenting it form a series of utterance most of the time.He has to judge， and spend great efforts on achieving phonological form of a word. He readjusts and practices a lot to pronounce it like adults thus being able to communicate with them. The reason for their hardworking on this is that aural input occupies their main linguistic data at the beginning period of word learning.

The power to provide potential meanings for word begin when a child gains the insight that words are used to refer to objects， actions and things . But how do children determine what words mean? According to developmental psycholinguists， children seem to rely on some assumptions to have a guess at the meanings. Still young children need somewhat adults' feedback or reaction which helps them determine the proper meaning. Such is a process of mapping the meanings onto the forms. Both experimental and anecdotal evidence suggests that children are good at fast mapping and that they can come to grasp aspects of the meaning of a new word on the basis of only a few incidental exposures .

3. Using the word and consolidating the word form， meaning and concept

A further step of word acquisition is using words appropriately in communication. Children have enough intentions to use words in their daily interactions with adults. Such intentions drive children to connect concepts with words and relate the forms to the meaning and concept， and is established firmly in children’s permanent memory.

Ⅲ. The Steps in Adults’ Word Learning

According to the model presented by Brown and Payne in their analysis of Adults' vocabulary learning， the process of word learning in Adult learners often includes the following five steps.

1.Having resources for encountering new words.

2.getting a clear image， either visual or auditory or both， for the forms of the new words.

3.learning the meaning.

4.making a strong memory connection between forms and meanings.

5.using the word.

This is a good generalization of the vocabulary learning steps. But the steps of adults' word learning， in fact， may be much more complicated than that. It can fall into the steps as follows.

1.Having resources for encountering new words

While reading or communicating with other adult English learners， an adult English learner encounters a large amount of new words. He may retain them in the sensory stores for a while， then deliver them to the working memory where further processing will be conducted to them.

2.Making inference on the meaning of the words

When an adult meets with a new English word， he may focus on the written form first. He may try to get its pronunciation and meaning at the same time from the context. Nevertheless， evidence shows that adult learners are much poorer at making predictions in context than children while learning new words. It seems that the meanings of words are much emphasized in adults and that once the meanings are made clear， forms seem to enjoy less attention.

3.Learning the precise meaning

Often， adult learners gain the precise meaning by consulting certain resources or references. They may already create a potential meaning of the new words by inferring from the context；they get adjustment or confirmation of the potential meaning and they quickly map this fraction of meaning onto the form， being ignorant of other aspects of the meaning.

4.Consolidating word form and meaning

After fast mapping of meanings onto forms， they try to consolidate them in memory. Facing the explanations in second language and the first language， they may choose the latter because it's much easier for them. Therefore， the bond between word forms and their native terms may be stronger than with explanations in a foreign language. When reading with a new word， adult learners tend to retort to their native tongue.

5.Using the word

To acquire a second language word is not equal to just knowing its phonological， orthographic information and interpretations in the first language or second language. Just speaking out a word and offering spelling and meaning may not secure second language learner's acquisition of it. They might know little of its other usages thus leading to failure in producing with second language words. Second language learners often find themselves at a loss when using second language in writing or speaking because they are short of productive vocabulary. Learning how to use second language words seems to be their urgent task for communication. However， this crucial step often receives less attention and efforts as well.

Learning a second language， as we know， involves complex mental processing and that it is by no means just memorizing the word form and it primary meaning. Much more information about words will be lost if learners take that narrow view.

Ⅳ. Conclusion

To sum up， processing in children’s mother tongue word acquisition consists of various tasks like mapping meanings onto forms， adjusting the boundaries of initial mapping and adding other entries of information to the original word meaning， etc. During the course of it， children， when learning the first language， rely on conceptual assumptions as well as pragmatic assumption， to fulfill the tasks， so as to set up the lexicon. There are similar steps in lexical learning of adults' second language learning on the whole， but the micro process of it differs. Children have to build up a conceptual knowledge of the word while learning word whereas adult learners have to fight off their negative transfer in first language to take in second langrage lexicon with less conceptual load. As to strategies involved in children's and adults' lexical learning， children are believed to rely more on assumption to figure out meaning and to employ more imagery and aural strategies to memorize forms and meanings. Second language learners， in contrast， taking advantage of their ready-made conceptual and semantic content， use semantic-related mnemonics a lot. They quite often resort to semantic and conceptual information in their mother tongue to develop their second language lexicon.

Based on the above study， second language learners may: ①create favorable linguistic environment for lexicon acquisition. ②capture all aspects of word information.③fight off the interference of their mother tongue.

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(作者單位：吉林長春大學(xué)光華學(xué)院）