How to Trace the Growth in Learners’ Active Vocabulary? A Corpus-based Study

Abstract

This paper reports on a study whose aim was to compare the validity, applicability and meaningfulness of two measures of lexical richness – lexical variation and lexical sophistication – for tracing the growth in learners’ free active lexicon. In addition, the study aimed at describing and analysing the increase in receptive and free (i.e. unelicited) productive vocabulary in advanced learners of English at two different proficiency levels. The research was based on a selection of texts from the PELCRA corpus of learner English compiled at the University of Łodź. The sample contained essays written by two groups of advanced learners. The results of the Vocabulary Levels Test for passive vocabulary size (Nation 1990) administered to the same students were also used in the study. Various measures of lexical richness were calculated for the essays: lexical variation was expressed by the Type/Token Ratio, the Standardised Type/Token Ratio and the Mean Type/Token Ratio; lexical sophistication was represented by the Lexical Frequency Profile and the Condensed Lexical Frequency Profile. A series of t-tests comparing all these measures for the two groups of essays were run. Moreover, the measures were correlated with the results of the Vocabulary Levels Test.The three type/token ratios employed in the study produced ambiguous results because they may be sensitive to text type and content. Both lexical Lexical Frequency Profile proved to be clearer, easier for interpretation and to discriminate better between the two groups, which suggests that it is the most valid and meaningful instrument for measuring the increase in learners’ output lexicon.The investigations of the growth in learners’ passive and active lexical stores have important implications for language pedagogy. They can allow to establish how the quantitative aspects of vocabulary knowledge change as a function of time, proficiency or language exposure. Consequently, they can help to set feasible lexical goals for second language education.