In studies of bilingual word recognition with masked priming, first language (L1) primes activate their second language (L2) translation equivalents in lexical decision tasks, but effects in the opposite direction are weaker (Wen & van Heuven, 2017). This study seeks to clarify the relative weight of stimulus-level (frequency) and individual-level (L2 proficiency, L2 exposure/use) factors in the emergence of asymmetrical priming effects. We offer the first data set where L2 proficiency and L1/L2 exposure/use are simultaneously investigated as continuous variables, along with word frequency. While we replicate the asymmetry in priming effects, our data provide useful insights into the factors driving L2–L1 priming. These fall almost exclusively under the category of stimulus-level factors, with L2 exposure/use being the only experiential variable to show considerable influence, although complex interactions involving L2 proficiency and word frequency are also present. We discuss the implications of these results for models of bilingual lexical processing and for the appropriate measurement of experiential factors in this type of research.

This research reports on a quantitative analysis of the combination of two types of disfluency, reformulations and pauses, in the speech of lower intermediate and advanced speakers of English as a second language (L2). The present study distinguishes between corrections and false starts within the category of reformulations as well as between silent and filled pauses. It focuses on the extent to which pause behavior within reformulations varies according to the stage of L2 development and the type of reformulation used. An analysis was made of 56 L2 speakers’ 2-min monologues. The results showed that lower intermediate and advanced speakers differed on the frequency of silent pauses inserted in corrections but not on their frequency in false starts. This suggests that false starts depend less on proficiency level, and may reflect temporary problems with conceptual encoding or extralinguistic factors that contribute to the efficacy of L2 production rather than difficulties with linguistic processing per se. The frequency of silent pauses rather than silent pause duration or the frequency and duration of filled pauses appeared to be the only marker to differentiate between false starts and corrections across the two proficiency groups.

In an ongoing debate, bilingual research currently discusses whether bilingualism enhances non-linguistic executive control. The goal of this study was to investigate the influence of language-switching experience, rather than language proficiency, on this bilingual executive control advantage. We compared the performance of unbalanced bilinguals, balanced non-switching, and balanced switching bilinguals on two executive control tasks, i.e. a flanker and a Simon task. We found that the balanced switching bilinguals outperformed both other groups in terms of executive control performance, whereas the unbalanced and balanced non-switching bilinguals did not differ. These findings indicate that language-switching experience, rather than high second-language proficiency, is the key determinant of the bilingual advantage in cognitive control processes related to interference resolution.

In this study we examined how the introduction of a parallel finger-tapping task influences second language (L2) speech encoding mechanisms and monitoring processes, and how the level of proficiency impacts the efficiency and accuracy of L2 performance under single and dual task conditions. The results indicate that imposing dual task demands had a negative effect on the accuracy of lexical selection and the efficiency of error-correction processes. We argue that this can be explained with reference to attentional bottleneck effects on lexical selection processes and on monitoring. The findings also reveal that the level of L2 competence influenced both the speed and the accuracy of speech encoding processes and the efficiency of monitoring.

Sociologists typically assume that immigrants' acquisition of English as a second language follows the opportunities and motivations to become proficient in English, while many linguists argue that second language acquisition may be governed by maturational constraints, possibly biologically based, that are tied to the age at onset of language learning. In this article, I use U.S. census data to investigate the relationship between age at onset of second language learning and levels of English language proficiency among foreign-born adults in the United States. The overarching conclusion is that proficiency in a second language among adults is strongly related to age at immigration. Part of that relationship is attributable to social and demographic considerations tied to age at entry into a new country, and part may be attributable to maturational constraints. Many colleagues, spread across several disciplines, provided valuable comments on this research. Among them were Cynthia Fisher, Nancy Garrett, Susan Gonzo, John Hagan, Charles Hirschman, Tim F. Liao, Michael Long, John Mardeen, Madonna Harrington Meyer, C. Gray Swicegood, and Jack Veugeler.