Age/order of Vocabulary Acquisition Effects in the Foreign Language: A Lexical Decision Task

This study is intended to report the effect of age of acquisition on lexical decision latencies in a group of Persian-English bilinguals. Forty freshman university students were requested to perform the lexical decision task in a counter-balanced design using DMDX software on laptop. Forty five English words and several pseudowords as fillers were selected for the stimuli. The stimuli were selected based on three different levels of AOA, and were checked against the Persian version of Snodgrass and Vanderwart Naming Battery. Thirty words were matched in their AoA in both Farsi and English, and then divided into early acquired (Group 1) and late acquired words (Group 2). The third group consisted of 15 words, which were later acquired in Persian but early acquired in English. In so doing, we wanted to explore whether processing of L2 words was dependent on the first language AoA of the same words or not. The findings revealed that the second language (L2) age of acquisition had an effect on lexical decision latencies regardless of the age of acquisition of words in Persian. The means of both groups (1 and 3) pertaining to the early acquired words in English were significantly lower than those of the late acquired group (2), implying that perhaps L2 mental lexicon has its own system of representation and processing in beginner bilinguals contrary to the majority of models on L2 mental lexicon and theories, supporting a critical period in learning a second language. The findings of this study have implications for form-meaning interface and dissociation of declarative vs. procedural memory in bilingual mental lexicon research. Accordingly, future research should take into account the important role of AoA in foreign language mental lexicon representation and processing.