Bilingualism might prove to be an added burden for adults with ADHD, leading to reduced EF abilities. Alternatively, the current findings might be ascribed to over- or under-diagnosis of ADHD due to cultural differences between groups. These issues should be pursued in future research.

Aims: High frequency words are read more quickly and accurately than low frequency words, a phenomenon called the frequency effect. In the current study, we examine several possible predictors for explaining individual differences between bilinguals in their sensitivity to frequency in the second language: specific second language exposure and vocabulary; general language abilities (therefore also evident in native language performance); and general cognitive ability (non-linguistic sensitivity to regularities). Approach: We used an individual differences approach with unbalanced Hebrew–English bilinguals, two typologically different languages that do not share a writing system, which allows a clear discrimination between native language and second language exposure and vocabulary. Data and analysis: To examine frequency effects, 69 Hebrew–English bilingual adults completed lexical decision tasks in native language and second language. In addition, participants completed vocabulary tests in both languages, reported language use and proficiency, and performed a statistical learning task. Data were analyzed using linear mixed-effects models. Findings: The results demonstrated that only vocabulary knowledge in the second language was a significant predictor of frequency effects in the second language. In addition, neither sensitivity to frequency in the native language nor statistical learning ability (a measure of general sensitivity to regularities) predicted sensitivity to frequency in the second language. Originality: Using an individual differences approach with bilinguals of two typologically different languages that do not share a writing system allows us to distinguish between native language and second language proficiency, and therefore identify the unique contribution of predictive factors from each of the languages to efficient visual word recognition in second language. Implications: The current findings support the lexical entrenchment hypothesis and highlight the importance of testing a variety of bilingual populations.

Reading efficiently in a second language (L2) is a crucial skill, but it is not universally achieved. Here we ask whether L2 reading efficiency is better captured as a language specific skill or whether it is mostly shared across L1 and L2, relying on general language abilities. To this end, we examined word frequency and predictability effects in sentence reading, and tested the same readers in L1 and L2, recording participants' eye-movements. Participants were 57 undergraduate bilingual speakers of Hebrew and English, languages that use different scripts, allowing for a clearer distinction between L1 and L2 processing. Both word frequency and word predictability effects were more pronounced in participants' L2 than in the L1, suggesting that both lower level and higher-order processes in reading are sensitive to language proficiency. Further, frequency effects in the L2 were linked with L2 proficiency but not general language abilities, and L2 predictability effects were not associated with either variable. Finally, readers' frequency and predictability effects in L1 and L2 were not associated with each other. Taken together, these results suggest that for different-script bilinguals, efficient reading in the L2 is a highly specific skill, dependent upon proficiency in that language, and drawing less on L1 and general language ability.