Despite the multifactorial space of language experience in which people continuously vary, bilinguals are often dichotomized into ostensibly homogeneous groups. The timing of language exposure (age of acquisition) to a second language (L2) is one well-studied construct that is known to impact language processing, cognitive processing, and brain organization, but recent work shows that current language exposure is also a crucial determinant in these domains. Critically, many indices of bilingual experience are inherently subjective and based on self-report questionnaires. Such measures have been criticized in favor of objective measures of language ability (e.g., naming ability or verbal fluency). Here, we estimate the bilingual experience jointly as a function of multiple continuous aspects of experience, including the timing of language exposure, the amount of L2 exposure across communicative contexts, and language entropy (a flexible measure of language balance) across communicative contexts. The results suggest that current language exposure exhibits distinct but interrelated patterns depending on the socio-experiential context of language usage. They also suggest that, counterintuitively, our sample more accurately self-assesses L2 proficiency than native language proficiency. A precise quantification of the multidimensional nature of bilingualism will enhance the ability of future research to assess language processing, acquisition, and control.

Although bilinguals benefit from semantic context while perceiving speech-in-noise in their native language (L1), the extent to which bilinguals benefit from semantic context in their second language (L2) is unclear. Here, 57 highly proficient English–French/French–English bilinguals, who varied in L2 age of acquisition, performed a speech-perception-in-noise task in both languages while event-related brain potentials were recorded. Participants listened to and repeated the final word of sentences high or low in semantic constraint, in quiet and with a multi-talker babble mask. Overall, our findings indicate that bilinguals do benefit from semantic context while perceiving speech-in-noise in both their languages. Simultaneous bilinguals showed evidence of processing semantic context similarly to monolinguals. Early sequential bilinguals recruited additional neural resources, suggesting more effective use of semantic context in L2, compared to late bilinguals. Semantic context use was not associated with bilingual language experience or working memory.

In this comprehensive review by Baum and Titone, the authors promote the notion that bilingualism should be thought of as an agent of neuroplastic change over the life span. Their proposal offers a context within which to view early enrichment, one element of which is the early learning of two languages. The review points out the complexities of studying bilingualism and highlights empirical gaps in research that are critical to our understanding of how experience with language, especially exposure to two languages, might affect the neurocognitive system. The framework brings together disparate sets of studies in the literature across multiple methods, models, and disparate repertoires of descriptive terms.