Language acquisition is a well-established avenue for language change (Labov, 2007). Given the theoretical importance of language acquisition to language change, it is all the more important to formulate clear theories of transmission-based change. In this paper, we provide a simulation method designed to test the plausibility of different possible transmission-based changes, using the Tolerance Principle (Yang, 2016) to determine precise points at which different possible changes may become plausible for children acquiring language. We apply this method to a case study of a complex change currently in progress: the allophonic restructuring of /æ/ in Philadelphia English. Using this model, we are able to evaluate several competing explanations of the ongoing change and determine that the allophonic restructuring of /æ/ in Philadelphia English is mostly likely the result of children acquiring language from mixed dialect input, consisting of approximately 40% input from speakers with a nasal /æ/ split. We show that applying our simulation to a phonological change allows us to make precise quantitative predications about the progress of this change. Moreover, it forces us to reassess intuitively plausible hypotheses about language change, such as grammatical simplification, in a quantitative and independently motivated framework of acquisition.

This paper examines variation in the use of rhotics in Santomean Portuguese. In Portuguese, the distribution of rhotics is determined by syllable structure (Bonet & Mascaró, 1997). However, the emerging variety of Portuguese spoken in São Tomé and Príncipe diverges from the standard norm and shows great variability in its use of rhotics; specifically, Santomeans often use a strong-R in positions that require a weak-r in European and Brazilian Portuguese. Sociolinguistic interviews with 56 speakers from the capital of São Tomé and Príncipe and its surroundings provide 5287 data points for analysis. Based on the apparent-time construct (Bailey, 2004; Bailey et al., 1991), variation patterns show a language change in progress in the use of the strong-R, with younger speakers using it more frequently. Results also reveal the emergence of rhotic fricatives in the speech of Santomeans born after the independence of the country.

A key component of Labov's (2001:411) socially motivated projection model of language change is the hypothesis that adolescents and preadolescents undergo a process of vernacular reorganization, which leads to a “seamless” progression of changes in progress. Between the ages of approximately five and 17, children and adolescents increase the “frequency, extent, scope, or specificity” of changes in progress along the community trajectory (Labov, 2007:346). Evidence of advancement via vernacular reorganization during this life stage has come from peaks in the apparent-time trajectory of a change around the age of 17 (e.g., Labov, 2001; Tagliamonte & D'Arcy, 2009). However, such peaks do not rule out the alternative explanations of retrograde change or age-grading. This paper presents both apparent time and real-time evidence for vernacular reorganization. We observe the arrowhead formation—a counterpart of the adolescent peak—for quotative be like in a trend study of adolescents and young adults in Toronto, Canada. Our results rule out the alternative explanations for previously observed adolescent peaks.

Some Portuguese verbs have two past participle forms: one regular (stem + -do), and the other irregular (often identical to the first person singular present indicative). Per grammars, the perfect auxiliaries ter/haver take regulars, while irregulars appear with passive/adjectival ser/estar. To test these claims, we analyzed naturally-occurring data from Brazil (twentieth century) and Portugal (nineteenth and twentieth). We coded 1077 tokens from 21 verbs for ten predictors and performed mixed-effects logistic regressions in R. Irregulars appear with ter/haver 54% overall and in 68% of cases from Portugal. Our results demonstrate that past participle choice is determined by the interaction of several linguistic factors. While lexical verb is the most significant predictor of participle selection, verbs with irregular participles identical to the first person singular present indicative occur in the irregular significantly more than other verbs. We conclude that analogical processes underpin the variation. This conclusion allows us to adjudicate between competing accounts of past participle choice in Portuguese.

This paper examines individual differences in constraints on linguistic variation in light of Labov's (2007) proposal that adult change (diffusion) disrupts systems of constraints and Tamminga, MacKenzie, and Embick's (2016) typology of constraints. It is shown that, in pooling data from multiple speakers, some of the complexity in structured community variation may be overlooked. Data on rhoticity from speakers of Bristol English are compared to 34 previous studies of rhoticity in varieties of English around the world. Constraints found to be consistent across varieties are also found to be consistent across speakers of Bristol English, whereas those that differ between varieties also differ between individuals, implying that only those which differ are truly part of the grammar, and that these are indeed disrupted by diffusion.