Roles of decoding efficiency on second language incidental word learning

This study investigated the roles of decoding efficiency in incidental word learning among second language (L2) learners with contrasting first language orthographic experiences. Although the effectiveness of incidental word learning in vocabulary acquisition has been widely recognized, little is known about its underlying processes. Based on previous findings from word recognition, transfer hypothesis, lexical memory, and working memory and reading comprehension studies, this study identified the major operations of incidental word learning as orthographic and phonological feature extraction, meaning inference, and feature-meaning linking. It was assumed that each operation requires working memory, and thus is facilitated by efficient decoding. It was also assumed that L2 decoding efficiency varies to the extent that L1 and L2 orthographies share similar structural properties.; The goal of this study was to investigate the effect of decoding efficiency on the component operations in incidental word learning. The following research questions were posed: (1) Does decoding efficiency predict efficiency in extracting the orthographic and phonological features of an unfamiliar word in L2 reading? (2) Does decoding efficiency predict success in inferring the meaning of an unfamiliar word in L2 reading? (3) Does decoding efficiency predict success in incidental word learning from L2 reading? (4) Does congruency of L1 and L2 orthographic backgrounds influence success in each operation of incidental word learning?; The participants were proficiency-matched college-level English L2 learners with alphabetic L1 backgrounds (N = 19) and non-alphabetic L1 backgrounds (N = 20). Their decoding efficiency was tested by a naming task. To simulate real-life incidental word learning, they read three passages, where target pseudowords to be learned were embedded, and then took feature extraction, meaning inference, and vocabulary knowledge tests. Results indicated that incidental word learning occurred in both groups. However, it was found that decoding played more facilitative roles for the alphabetic L1 group than it did for the non-alphabetic L1 group. This implies that decoding relates differently to incidental word learning among L2 learners with diverse L1 backgrounds.; The findings provided an understanding of the roles of decoding efficiency in incidental word learning, and the influences of L1 orthographic experiences in L2 incidental word learning. The findings also suggested that it is important to promote learners' decoding skills for their vocabulary knowledge improvement.