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Vocabulary Growth of the Advanced EFL Learner
Meral Ozturk*
Abstract
This article reports the results of three studies conducted between the years 2005-2010 on the vocabulary growth of advanced EFL university students in an English-medium degree programme. Growth in learners’ written receptive as well as productive vocabularies was investigated in one longitudinal and two cross-sectional studies over three years. While the first two studies used the receptive and semi-productive versions of the Vocabulary Levels Test, study 3 used the more recent Vocabulary Size Test (Nation and Beglar, 2007). The overall results of the three studies suggested that learners’ vocabularies did expand both receptively and productively, however the growth was rather modest. Learners' receptive vocabulary sizes were 5-6,000 words and expanded by about 500 words a year. There was also evidence for severe attrition in the final year. Productive vocabulary expanded by 10% in the longitudinal study. Receptive knowledge of academic vocabulary did not improve significantly due to a ceiling effect, but productive growth was significant. Frequency seems to have a stable overall effect in vocabulary development. However, for only one of the three tests used (i.e. the Vocabulary Levels Test) an implicational scale between the levels could be established.
Keywords: vocabulary growth, vocabulary size, receptive vocabulary, productive vocabulary, frequency, advanced learner, EFL
Introduction
A large vocabulary size is important in using English. Research has shown that for written receptive tasks like reading newspapers, novels, or academic texts, 8-10,000 words1 are necessary (Nation, 2006; Hazenberg and Hulstijn, 1996), and for spoken receptive tasks like watching English TV programmes or movies, 7-8,000 words are needed (Webb and Rodgers, 2009a; Webb and Rodgers, 2009b). For most EFL learners, these targets are quite challenging if not impossible to attain. Part of the reason is that English language courses do not usually target vocabulary beyond a few thousand (Cobb, 1995) on the assumption that having mastered the core vocabulary of English (i.e. the most frequent 2000 or so words) learners will maintain progress on their own. While in the earlier stages of language learning vocabulary learning is guided by the teacher and the coursebook, the advanced learner is left to their own devices to learn a large vocabulary mainly through language use. The question is whether extended language use promotes such learning and whether learners continue to expand their vocabularies fast enough to achieve the desired sizes. Another issue concerns patterns of lexical development. Do L2 learners’ vocabularies grow in predictable ways, or do they grow idiosyncratically depending on individual learners’ personal interests and needs? The present study will investigate the potential of word frequency to predict the path of development. Word frequency has long been a major guiding principle in setting lexical targets for L2 learners, and it is assumed that learners should and will proceed according to frequency. However, few studies have so far empirically tested it. The present study will investigate these questions in relation to EFL learners who use English for academic purposes in English-medium degree programmes. As noted by Meijer (2006), English-medium programmes are spreading in non-English-speaking countries ‘especially but not exclusively in Europe’ and the kind of learner concerned does not represent a marginal subset of English language learners.
L2 Vocabulary Growth
The literature on L2 vocabulary growth is rather small and only three of these studies (Cobb & Horst, 2000; Schmitt & Meara, 1997; Milton & Meara, 1995) specifically deal with vocabulary growth through academic study at the tertiary level while others involve learning through direct language study in language courses rather than learning through language use (Milton, 2009, pp.79-85; Laufer, 1998; Read, 1988). Unfortunately, the results of these studies are conflicting regarding the evidence for progress. While Milton & Meara (1995) report significant gains in the learners’ receptive vocabularies, the other two fail to provide evidence for any substantial expansion of vocabulary size (Cobb & Horst, 2000; Schmitt & Meara, 1997). Growth rates reported in these studies also vary considerably. Milton and Meara (1995) investigated receptive vocabulary growth of European exchange students in a British university and they estimated the annual growth rate to be 2650 words on average. On the other hand, Cobb and Horst (2000) found that the second year students’ receptive vocabularies in a university in Hong Kong differed from the first years’ by only 200 words, and the first years did not make any significant gains after six months. Schmitt and Meara’s (1997) EFL learners in Japan gained only 330 words receptively in a year. Obviously, more data from similar contexts are needed in order to gain insight into the nature of vocabulary growth of these learners.
The present study will improve on previous research in many ways. All three of the aforementioned studies were limited in duration, not exceeding one year, during which sizebale gains may be hard to surface. The present studies, on the other hand, will cover a much longer time span, i.e. three years. While previous studies looked at receptive size only, the studies in this paper will look at both receptive and productive size. The only other study which investigated productive growth is Laufer (1998), who found an increase by 850 words in the vocabularies of her high-school learners in Israel after one year of language study. In the present research, both cross-sectional (studies 1 and 3) and longitudinal (study 2) designs will be employed. While the first two studies will use the receptive and (semi-) productive Vocabulary Levels Test (Nation, 2001) to measure vocabulary size, study 3 will use the recently developed Vocabulary Size Test by Nation and Beglar (2007).
Growth in academic vocabulary, i.e. subtechnical vocabulary that occur frequently across a variety of academic disciplines but are not so common in non-academic texts (Nation, 2001, p.187), will also be investigated. Although growth in this area is to be expected given the opportunities for exposure to academic vocabulary, Cobb and Horst (2000) did not find evidence for progress in the knowledge of academic words of the first year students over six months or from the first to the second year. Conducted under similar conditions, the present study will investigate if significant gains could be obtained over several years of academic study.
It is expected that the context of the English-medium degree programme where the three studies that will be reported here were conducted will provide enough immersion in the target language to induce vocabulary development. However, the generally held conviction among the students in the programme that their English proficiency in general and vocabulary knowledge in particular deteriorated in the course of their studies runs counter to this expectation. The present study will shed light on this as well.
The Frequency Effect
An important factor affecting vocabulary development in a second language is frequency of words in the language. Frequency exerts its influence through input. In the L1, learners are exposed to words of varying frequency in receptive language use, and words that appear more often in the input stand better chance of being learnt as repeated encounters raise salience of the word, provide richer clues to meaning, and strengthen memory traces. Vermeer (2001), in a study with native English-speaking children in primary education, found significant correlations between the frequency of a word in the input and the probability of knowing it. In L2 vocabulary acquisition, frequency is likely to have a stronger effect. Input to L2 learners is usually graded in vocabulary difficulty which is largely decided on the basis of word frequency, to the effect that high frequency vocabulary becomes even more frequent and effect of frequency more pronounced. Several studies have provided evidence for a frequency effect. Even though frequency is a continuous variable, these studies used test instruments where test words were drawn from lists of words divided, for the sake of convenience (Meara, 2010, p.3), into one-thousand-word bands of frequency. These studies have shown significant differences in scores between frequency levels and a decrease in knowledge as the frequency level decreased. Laufer et al. (2004) measured vocabulary knowledge of adult ESL learners with intermediate to advanced proficiency in English in four one-thousand-word bands of frequency (2K, 3K, 5K and 10K) using the Vocabulary Levels Test, and found that higher frequency words at 2K and 3K levels were easier for these learners than the lower frequency words in the 5K level which, in turn, were easier than the 10K level words. Milton (2009) reports a similar pattern in Greek learners whereby learners' knowledge of words were highest at the 1K level and steadly decreased over the following four adjacent levels of lower frequency. Laufer & Paribakht (1998) have also found increasingly higher scores across the frequency levels. Milton (2007) formulates this as ‘the frequency model of lexical learning’ profiling learners’ knowledge over frequency levels on a graph borrowed from Meara (1992). The following graph is the vocabulary profile of a typical learner.
Figure 1. Vocabulary profile of a typical learner (Meara, 2010, p.6)
The model claims that ‘a typical learner’s knowledge is high in the frequent columns and lower in the less frequent columns giving a distinctive downwards slope from left to right. As learner knowledge increases, this profile moves upwards until it hits a ceiling at 100% when the profile ought to flatten at the most frequent levels and the downwards slope, left to right, shifts to the right into less frequent vocabulary bands.’ (Milton, 2007, p.49). Milton’s own research (2007, 2009) generally supported the model yielding normal frequency profiles for 60% of the learners. On the other hand, a substantial proportion of learners deviated from a normal profile and even the most able learners were not able to hit the 100% ceiling in the highest frequency levels but plateaued at around 85-90%. This suggests that while frequency has a strong effect in vocabulary learning other factors might be at play.
Some researchers went further and looked for the presence of an implicational scale among the levels. Read (1988) has shown that frequency levels in the VLT form an implicational scale whereby a learner ‘…who achieved the criterion score at a lower frequency level-say, the 5,000-word level- could normally be assumed to have mastered the vocabulary of higher frequency levels - 2,000 and 3,000 words- as well’ (Read, 1988, p.18). This finding has been replicated by Schmitt, Schmitt & Clapham (2001).
While frequency is clearly an important factor in vocabulary learning, the case for frequency could be made from previous studies only for the earlier stages of vocabulary learning since the test instruments used either did not measure knowledge in lower frequency levels beyond 5K (X-Lex in Milton 2007, 2009) or measured only the 10K level skipping the levels in between (Vocabulary Levels Test in other studies). Frequency might not have the same strong effect on vocabulary learning in advanced levels as in earlier levels. Since words that need to be learned at an advanced level will generally be of low frequency, other factors like personal interest might become more decisive in determining which words are learnt. The present study will test for an implicational scale covering a greater range of frequency levels in receptive vocabulary knowledge in study 3. The presence of an implicational scale will also be tested for productive vocabulary knowledge in studies 1 and 2. Vocabulary Levels Test (VLT from now on) scores in studies 1 and 2 will also be investigated for an implicational scale for the sake of comparison.
The three studies here will seek for answers to the following research questions:
1. Do the written receptive and written productive vocabulary sizes of advanced EFL learners in English-medium degree programs continue to grow over time and at what rate do they grow?
2. Does the knowledge of academic vocabulary in a foreign language develop receptively and productively through academic study?
3. Do word frequency levels form an implicational hierarchy in developing a written receptive and a written productive vocabulary in a foreign language through academic study?
Study 1
Fifty-five first-year and forty-five fourth-year students in four intact classes in the ELT programme in a university in Turkey participated in the study. All spoke Turkish as their L1. They were highly advanced in English as they had to pass a very competitive national English test to be admitted to the programme. In the department, they were immersed in an English language environment, which should be conducive to further development of vocabulary. Beginning from the first-year, all intradepartmental courses are offered in English and take up 73% of all the courses in the four-year curriculum and 74% of the credit hours that have to be taken to graduate from the programme. In these courses, the course material, lectures, class discussions, oral presentations, written projects and exams are mediated through English. English language skills courses are offered in the first year and the rest of the courses are related to learners’ subject area which includes linguistics, English language teaching, language acquisition, and English literature.
Study 1 employed a cross-sectional design comparing the first- and fourth-years in terms of English vocabulary size. Any difference in vocabulary size between the two groups is assumed to be the result of the extra years of exposure to English through academic study by the fourth-year group as both groups studied under similar conditions in the programme. Both groups had to take the same courses throughout with the exception of a few interdepartmental elective courses which are taught in the learners’ L1; both groups were taught by the same teachers as the staff is pretty stable; and the course material is unlikely to have grossly differed in the three intervening years. Initial English proficiency and vocabulary size of the two groups is likely to be very similar since the national English test admits students to the department from a very narrow range of scores each year. However, the method of calculation of the national test scores has been changed between the years when the fourth-years and the first-years sit the English test (the years 2002 and 2005 respectively) and therefore a direct comparison of the learners’ initial proficiency scores was not possible. On the other hand, the content of the test has not changed from the year 2002 to 2005. In both occasions, 60% of the items measured reading comprehension, 25% tested grammar and vocabulary and 15% were translation items. Thus, both groups studied for the same kind of an exam, and any washback effect from the test has probably led to the development of the same kind of linguistic skills in English.