Evidence from various empirical study types have converged to show bilingualism's potential for serving as a cognitive and brain reserves contributor. In this article, I contextualize, frame the need for and offer some expanding questions in this endeavor, inclusive of empirical pathways to address them. While the set of variables and questions discussed herein are definitively incomplete, they embody a good starting point for shaping future directions in research that considers the role bilingual language engagement can have for the developing mind and brain, inclusive of how various, non-linear factors impact the descent bilinguals of various types take down the proverbial mountain of life.

This study examined the acquisition of numeral classifiers in 120 monolingual Japanese children. Previous research has argued that the complex semantic system underlying classifiers is late acquired. Thus, we set out to determine the age at which Japanese children are able to extend the semantic properties of classifiers to novel items/situations. Participants completed a comprehension task with a mouse-tracking extension and a production task with nonce and familiar items. While the comprehension results showed ceiling effects on familiar and nonce items, age significantly modulated a difference in accuracy between familiar and nonce items in the production task. The findings suggest that the acquisition of the underlying semantic system is acquired much earlier than previously argued. Previously attested issues with Japanese classifier production in young(er) children are more likely to reflect accessing difficulties than indexing the underlying grammatical competence of the classifier system.

Bilingualism has been shown to contribute to increased resilience against cognitive aging. One of the key brain structures linked to memory and dementia symptom onset, the hippocampus, has been observed to adapt in response to bilingual experience – at least in healthy individuals. However, in the context of neurodegenerative pathology, it is yet unclear what role previous bilingual experience might have in terms of sustaining integrity of this structure or related behavioral correlates. The present study adds to the limited cohort of research on the effects of bilingualism on neurocognitive outcomes in Mild Cognitive Impairment (MCI) using structural brain data. We investigate whether bilingual language experience (operationalized as language entropy) results in graded neurocognitive adaptations within a cohort of bilinguals diagnosed with MCI. Results reveal a non-linear effect of bilingual language entropy on hippocampal volume, although they do not predict episodic memory performance, nor age of MCI diagnosis.

Despite a meteoric rise, results in the cognitive science of bilingualism present with significant inconsistency. In parallel, there is a striking absence of an ecologically valid theory within bilingualism research. How should one interpret the totality of available data that can pull in opposing directions? To proceed, we need to identify which practices impede progression. Hitherto, we bring to the fore an undiscussed practice, contextualizing how it impacts the ability to embed the available results into an overarching theory. We suggest that a stacking the deck fallacy – the tendency to engage differently with available evidence, directing focus to specific sub-samples – hampers theory formation. We put forth a proposal for making progress, building on the premise that what is lacking in the field is a unifying perspective that reconciles seemingly contradictory results. We suggest that the necessary shift of perspective towards progress crucially entails linking the notions of spectrum and trade-off.

Herein, we contextualize, problematize, and offer some insights for moving beyond the problem of monolingual comparative normativity in (psycho) linguistic research on bilingualism. We argue that, in the vast majority of cases, juxtaposing (functional) monolinguals to bilinguals fails to offer what the comparison is supposedly intended to do: meet the standards of empirical control in line with the scientific method. Instead, the default nature of monolingual comparative normativity has historically contributed to inequalities in many facets of bilingualism research and continues to impede progress on multiple levels. Beyond framing our views on the matter, we offer some epistemological considerations and methodological alternatives to this standard practice that improve empirical rigor while fostering increased diversity, inclusivity, and equity in our field.