In second language acquisition research, the critical period hypothesis (cph) holds that the function between learners' age and their susceptibility to second language input is non-linear. This paper revisits the indistinctness found in the literature with regard to this hypothesis's scope and predictions. Even when its scope is clearly delineated and its predictions are spelt out, however, empirical studies–with few exceptions–use analytical (statistical) tools that are irrelevant with respect to the predictions made. This paper discusses statistical fallacies common in cph research and illustrates an alternative analytical method (piecewise regression) by means of a reanalysis of two datasets from a 2010 paper purporting to have found cross-linguistic evidence in favour of the cph. This reanalysis reveals that the specific age patterns predicted by the cph are not cross-linguistically robust. Applying the principle of parsimony, it is concluded that age patterns in second language acquisition are not governed by a critical period. To conclude, this paper highlights the role of confirmation bias in the scientific enterprise and appeals to second language acquisition researchers to reanalyse their old datasets using the methods discussed in this paper. The data and R commands that were used for the reanalysis are provided as supplementary materials.

This study investigates the lifespan development of the ability to correctly guess the meaning of foreign-language words with known translationequivalent cognates. It also aims to identify the cognitive and linguistic factors driving this development. To this end, 159 German-speaking Swiss participants aged 10 to 86 were asked to translate 45 written and 45 spoken isolated Swedish words with German, English or French cognates. In addition, they were administered an English language test, a German vocabulary test as well as fluid intelligence and working memory tests. Cognate guessing skills were found to improve into young adulthood, but whereas they show additional increases in the written modality throughout adulthood, they start to decrease from age 50 onwards for spoken stimuli. Congruently with these findings, L1 vocabulary knowledge is a stronger predictor of written cognate guessing success, whereas fluid intelligence is the most important predictor in the spoken modality. Raw data and computer code used for the analyses are freely available online.

Aims and objectives: We investigate how varying usage patterns in speakers of closely related language varieties might impact executive function. More specifically, bidialectals with more balanced usage were predicted to show better inhibitory control than less balanced bidialectals. Design: Thirty-four adult bidialectals of Standard German and Swabian German performed two executive function tasks (flanker and Simon). Data and analysis: The participants’ reaction times on the two executive function tasks were analysed using regression models. Data and R code are available online. Findings: Contrary to predictions, Swabian-dominant bidialectals showed smaller flanker and Simon effects than balanced German-Swabian bidialectals. Furthermore, contrary to some previous studies, executive function task performances correlated significantly. Originality: We discuss how bidialectal language usage patterns can be assessed and how arbitrary analytical decisions affect findings regarding the effects of bidialectalism on executive function. Significance: These findings shed a new light on the effects of bilingualism/bidialectalism on executive function.

A classic topic in research on bilingualism across the lifespan is the relationship between the age at which learners start to acquire a second language (L2) and their ultimate level of proficiency in that language. Learning of an L2 that begins in infancy is typically associated with fluent speech, effortless language processing, and native accent. In contrast, late L2 learners tend to diverge from monolingual natives on measures of grammatical and lexical knowledge, processing speed, and acoustic properties of speech. Various classes of explanations for age effects in L2 acquisition-attitudinal, neurobiological, experiential, psychosocial, and cognitive-have been proposed in the literature. It is not the purpose of this chapter to examine these various accounts (for an overview, see Muñoz & Singleton, 2011). Similarly, with the exception of a brief discussion in the section on social concerns, this chapter does not consider research on the efficiency of early foreign language teaching in schools (for an overview, see Lambelet & Berthele, 2015). Rather, we are concerned with the hypothesis that L2 learning in naturalistic contexts is constrained by a critical period (CP). With its roots in the seminal works of Penfield and Roberts (1959) and Lenneberg (1967), the CP hypothesis for L2 acquisition (CPH/L2A) posits that nativelike attainment in the L2 from mere exposure is possible if learning begins within, but not after, a limited developmental span.Several recent overviews comprehensively summarize studies inspired by the CPH/L2A, and we do not intend to rehash these surveys. Instead, this chapter aims to provide readers with a technical toolkit to critically evaluate research on the divisive issue that is the CPH/L2A. To this end, we first discuss the CPH/L2A's prediction that nativelikeness among learners with post-CP age of onset of acquisition (AoA) is impossible and highlights epistemological difficulties with this prediction. We then turn to the nature of the function that relates AoA to L2 attainment. The logic here is that a discontinuous function, but not a straight-line function, properly reflects the workings of a critical period. Here we illustrate how seemingly minor technical (statistical) caveats, which often risk being brushed under the rug as nit-picking, can fundamentally affect the conclusions of a study. In the final section, we expand our scope by considering the relevance of L2 acquisition theory to the social context of L2 learners and users. Specifically, we examine three issues relating to the notion that late L2 acquisition is inferior to first-language (L1) acquisition: early instruction of foreign languages in schools, the emphasis on deficits versus capacities, and societal prejudices against non-nativelikeness.

This study investigated how standard and substandard varieties of first language (L1) Dutch affect grammatical gender assignments to nouns in second language (L2) German. While German distinguishes between masculine, feminine, and neuter gender, the masculine–feminine distinction has nearly disappeared in Standard Dutch. Many substandard Belgian Dutch varieties, however, still mark this distinction, making them more akin to German than Standard Dutch in this respect. Seventy‐one Belgian and 104 Netherlandic speakers of Dutch with varying levels of German proficiency assigned gender‐marked German articles to German nouns with Dutch cognates; these gender assignments were then compared to the cognates’ gender in the standard and substandard L1 varieties. While the gender assignments of both Belgian and Dutch participants were strongly influenced by the cognates’ Standard Dutch gender, the Belgians’ responses showed, at best, weak traces of the masculine–feminine distinction in substandard Belgian Dutch. Possible reasons for this weak substandard variety influence are discussed. Open Practices This article has been awarded Open Data, Open Materials, and Preregistered Research Design badges. All data, R code, materials, and appendices, along with preregistration for research design and analyses, are publicly accessible via the Open Science Framework at https://osf.io/5ahzj. Learn more about the Open Practices badges from the Center for Open Science: https://osf.io/tvyxz/wiki.