Do adults acquire a second orthography using their native reading network?

Abstract

Abstract Adult second language learners typically aim to acquire both spoken and written proficiency in the second language (L2). It is widely assumed that adults fully retain the capacity they used to acquire literacy as children for their native language (L1). However, given basic principles of neural plasticity and a limited body of empirical evidence, this assumption merits investigation. Accordingly, the current work used an artificial orthography approach to investigate behavioral and neural measures of learning as adult participants acquired a second orthography for English across six weeks of training. One group learned HouseFont, an alphabetic system in which house images are used to represent English phonemes, and the other learned Faceabary, an alphasyllabic system in which face images are used to represent English syllables. The findings demonstrate that adults have considerable capacity to learn a second orthography, even when it involves perceptually atypical graphs, as evidenced by performance improvements that were sustained across weeks of training. They also demonstrate that this learning involves assimilation into the same reading network that supports native literacy, as evidenced by learning related changes in orthographic, phonological, and semantic regions associated with English word reading. Additionally, we found learning patterns that varied across the two orthographies. Faceabary induced bilateral learning effects in the mid-fusiform gyrus and showed greater engagement of regions associated with semantic processing. We speculate the large graph inventories of non-alphabetic systems may create visual-perceptual challenges that increase reliance on holistic reading procedures and associated neural substrates.