The Effects Of Input Frequency Of Textbooks On L2 Vocabulary Acquisition

Input frequency is an important issue in the field of second language acquisition (SLA) and people have been interested in how input frequency affects SLA. Ellis (2002) claimed that frequency was a fundamental cognitive mechanism in every domain of language processing and frequency was critical in language processing.Many studies have been carried out to examine the relationship between input frequency and second language acquisition. It has been found that input frequency does have an influence on L2 acquisition (Ferris 1988, Rott 1999 and Horst 2000). However, there still exist some problems and questions which need to be dealt with. For example, in Ferris's study (1988), no measures were taken to strictly control the numbers of encounters of the target words and participants had other opportunities to meet the target words. Therefore, the number of occurrences of a word in the texts might not be an accurate reflection of the number of encounters of the target word. In Rott's study (1999), only six new words were exposed to the subjects. Such a small sample of target words can not guarantee a comprehensive picture of the effect of input frequency.Even though some empirical studies were supportive of a role for frequency (Bley-Vroman 2002, Hulstijn 2002, Eubank & Gregg 2002, Gass & Mackey 2002, Larsen-Freeman 2002) , causal claims should be made cautiously. Some other factors such as cognitive salience, noticing of learners, complexity of word meaning, L1 transfer and communicative need may also have an influence on SLA.As there are some problems and unclear questions about the effects of input frequency in previous studies, this paper aimed at further investigating the effects of input frequency of textbooks on L2 vocabulary acquisition. The research questions are:(1) What is the relationship between input frequency and L2 vocabulary acquisition?(2) What factors may influence the efficacy of input frequency?626 college students were participated in the study. Two vocabulary tests were administered and an interview was made after the tests.The major findings of the study are as following:(1) The results of the data analysis show a clear tendency that correction rates of the target words in the vocabulary tests increase with the increase of the input frequency. The higher the input frequency is, the higher the correction rates are. Therefore, it can be said that input frequency does have an effect on the acquisition of L2 vocabulary as previous studies have manifested.(2) The average correction rates of the target words in Vocabulary Test One which occur six times or over are all above 50%. The correction rates of the words which occur fewer than six times are lower than 50%.To some extent it can be said that six occurrences can be considered as a threshold input frequency for substantial acquisition of a word to take place.(3) Even though the general tendency is that input frequency has an effect on the acquisition of L2 vocabulary, it cannot fully account for all vocabulary acquisition. The results of correlation analysis show that input frequency has a significant but low correlation with the correction rate. The correlation between input frequency and the results of Vocabulary Test One is r=.286 (p=.000). The correlation between input frequency and the results of Vocabulary Test Two is r=.35 (p=.000).(4) There are intra-group variations concerning the correction rates of the target words. Within the groups, we can see that words with higher input frequency may not have higher correction rates and words with lower input frequency may have higher correction rates.There may be a number of reasons that can explain why some of the target words with higher input frequency have low correction rates. One reason is that they were never noticed by the learners. The students failed to notice the target words either because they occur in the exercises or because they are not salient enough to catch the attention of the students or the students didn't get as many repetitions as theoretically alleged because not all the texts in the textbook were taught by teachers in the class. Another reason is that the irrational distribution of words in the textbooks and intrinsic features of the target words have added the learning burden of some target words.There may also be a number of reasons that can explain why some of the target words with lower input frequency have higher correction rates. First, some of the target words with lower input frequency had been learnt in high schools. Second, some words with lower frequency were made salient in word forms through a number of ways such as wordlist, instructional focus, and special treatment of characters in the textbooks. Third, compounds and derivational regularity could reduce learning difficulties and learning burden.(5) There are also inter-group variations concerning the correction rates of the target words. Between the groups, it is found that the second-year students' vocabulary correction rates were much lower compared with the first-year students. Possible reasons include 1) the proportion of words which has never been seen before and that of words which have been seen but failed to be learnt in Vocabulary Test Two are higher than the proportions in Vocabulary Test One, 2) the irrational distribution of the target words in the three textbooks has made vocabulary learning difficult and 3) second-year students did not put as much time on vocabulary learning as the first-year students.