English monolinguals (Experiment 1) and first language (L1)-dominant, Spanish-English and Chinese-English bilinguals (Experiment 2), who differed in L1 orthographic depth (shallow: Spanish; deep: Chinese) and second language (L2–English) proficiency, decided whether visually presented letter strings were English words, while behavioral and EEG measures were recorded. The spelling-sound regularity and consistency of stimuli were covaried such that words had either regular/consistent (e.g., GATE) or irregular/inconsistent mappings (e.g., PINT). Irregular/inconsistent words elicited more positive P200 and less negative N400 amplitudes than regular/consistent words in monolinguals, yet only a P200 response in bilinguals. English proficiency modulated L2 reading strategies, such that bilinguals employed distinct reading unit sizes in the L2 than the L1 when L2 proficiency was low, but transferred L1 reading units to the L2 when L2 proficiency was high. ERP results suggest that high L2 proficiency may be a prerequisite to the cross-linguistic transfer of reading strategies.

To capture the complexity of foreign language literacy acquisition, we investigated cognitive skills underlying word reading, sentence reading, word vocabulary and sentence vocabulary in three different foreign languages. Students fluent in Dutch simultaneously acquired three foreign languages that differed in orthographic transparency and writing system (Spanish, French, Chinese). Cognitive skills at the start of literacy acquisition (Grade 7) were longitudinally related to literacy attainment in each of the foreign languages after two years of instruction (end of Grade 8). Structural equation regression models indicated that three areas (word and sentence vocabulary, and sentence reading) related most strongly to verbal and nonverbal intelligence, indicating the involvement of academic skills. For word reading the influence of cognitive skills appeared language specific. Across languages, native reading skills seemed to be employed to varying degrees of efficiency to decipher foreign words, more so for foreign languages with a smaller orthographic distance from the native language.