The Relationship between Receptive and Productive Affix Knowledge and Vocabulary Size in an EFL Context

Abstract

Affix knowledge, the ability to use prefixes and suffixes, is an essential mechanism for vocabulary acquisition and growth. Research demonstrates a positive relationship between affix knowledge and vocabulary size yet little is known about how these English affixes are acquired. Therefore, this study investigated the nature of affix acquisition, in terms of linguistic and psycholinguistic features, using Bauer and Nation’s (1993) word family construct. The study also aimed to determine whether, and to what extent, receptive and productive affix knowledge contributes to vocabulary size. A total of 486 Thai EFL participants participated in the study. The participants were 14-17 years old and were students in grades eight to eleven at a public school. The participants were given two existing vocabulary size tests and three measures of affix knowledge. Affix knowledge measures were designed and piloted specifically for this study to measure the participants’ receptive and productive affix knowledge. Correlational and multiple regression analyses were used to examine the relationship between different dimensions of affix knowledge and vocabulary and to determine the statistical contribution of variance in affix knowledge to vocabulary. Qualitative analysis of the multiple-case design was also used to explore the pattern of sentence composition in small versus large vocabulary participants. The results confirmed a positive relationship between Thai EFL learners’ receptive and productive affix knowledge and their receptive and productive vocabulary size. Furthermore, Thai EFL participants’ affix learning followed a five-stage taxonomy of affix acquisition: inflections, prefixes, verbs, nouns, and adjectives and adverbs. This taxonomy was acquired at different speeds and varying degrees. These findings support previous claims that the development of the L2 lexicon is complex and incremental. Furthermore, knowledge of affixes in English functions as a building block for word knowledge and the acquisition of the affix is multidimensional and incremental. Future research would benefit from longitudinal studies designed to examine more precisely this mechanism, including internal and external factors. Such research would provide additional important pedagogical and theoretical implications.