This study examines three formal linguistic acquisition models of third language (L3) acquisition in the context of Brazilian Portuguese (BP), specifically examining Differential Object Marking (DOM). The main goal is to determine which of the models is best able to predict and explain syntactic transfer in three experimental groups: mirror-image groups of first/second language (L1/L2) English/Spanish bilinguals (i) L1 English/L2 Spanish and (ii) L1 Spanish/L2 English, and (iii) heritage Spanish/English bilinguals. The data provide evidence to support the Typological Primacy Model (Rothman, 2010, 2011, 2013), which predicts Spanish transfer irrespective of its status as an L1, L2 or bilingual first language (2L1). Additionally, the heritage speaker and L1 English group results, taken together, provide evidence for Iverson's (2009) claim that comparing such populations adds independent supportive evidence that the acquisition of linguistic features or properties in an L2 acquired past puberty is not subject to a maturational critical period.

The present study investigates variability in heritage speakers’ (HSs) knowledge of inalienable possession in Spanish (e.g., me rompí el brazo: ‘I broke my arm’). By testing HSs’ productive and receptive knowledge of this property, the study fills an important gap in the literature and, furthermore, explores whether differences in performance across productive and receptive modalities reflect grammatical innovation at the level of underlying representation. Thirty HSs (16 advanced proficiency, 14 intermediate proficiency) and 15 Spanish-dominant controls (SDCs) completed two experimental tasks, each testing both inalienable and alienable object contexts. Results from the Elicited Production Task show that the HSs exhibit significant variability. Unlike the SDCs, who almost categorically produce clitics to communicate the inalienability of objects, the two HS groups rely more heavily on possessive determiners, alternating frequently between the “target” form (Clitic + DefDet: me rompí el brazo) and three different “innovative” variants (e.g., NoClitic + PossDet: rompí mi brazo). Results from the Acceptability Judgment Task complicate this finding by revealing that the HSs, despite their productive variability, make all of the same within-group distinctions as the SDCs, suggesting that they retain systematic receptive knowledge of inalienable possession. To explain these seemingly contradictory patterns, as well as the strong effect of Spanish proficiency on HSs’ performance across tasks, we suggest that HSs’ variability is consistent with English to Spanish influence at the level of bilingual alignments, transient storage mechanisms proposed by Sánchez (2019) to account for gradient and variable performance in multiple bilingual contexts.

Previous studies (e.g., van Osch & Sleeman 2016; Perez-Cortes 2016) have found that heritage speakers (HSs) of Spanish produce less lexically-selected subjunctive mood morphology than Spanish-dominant speakers. It remains unclear, however, whether the HSs’ tendency to produce less subjunctive mood than Spanish-dominant speakers is attributable to representational differences (e.g., Montrul 2002, 2008), input quality differences (e.g., Pires & Rothman 2009; Pascual y Cabo & Rothman 2012), or as yet unidentified factors. The present study addresses this question by testing the effect of lexical frequency on advanced proficiency HSs’ productive (Experiment 1) and receptive (Experiment 2) knowledge of lexically-selected subjunctive mood in Spanish. Results of Experiments 1 and 2 indicate that advanced proficiency HSs are both (a) highly accurate with subjunctive mood and yet also (b) significantly less accurate with lower frequency verbs. Given these findings, as well as the categorical subjunctive production of the Spanish-dominant bilingual control group, it is argued that HSs’ differences from dominant speakers may be (partially) attributable to gaps in lexical, rather than morphosyntactic knowledge.

Many previous studies have found that adult heritage speakers exhibit significant variability in their production and comprehension of mood morphology in Spanish. Nonetheless, it remains unclear what specific factors predict heritage speakers’ likelihood of exhibiting such variability. The present study contributes to this question by testing the effect of both (a) age-of-acquisition of English and (b) Spanish proficiency on heritage speakers’ productive and receptive knowledge of mood morphology. Seventeen “early” heritage speakers (age of acquisition of English: 0 to 3.5 years), 20 “late” heritage speakers (age of acquisition of English: 4 to 6 years), and 18 later childhood immigrants (age of arrival in the US: 8 to 12 years) completed a Contextualized Elicited Production Task and a Mood Preference Task. Results of the two experiments suggest that the later childhood immigrants, despite “overusing” subjunctive in +Presupposition adjectival relative clauses, are significantly more likely than “early” and “late” heritage speakers to produce and prefer subjunctive mood in expected subjunctive contexts (with para que and in -Presupposition adjectival relative clauses). Within the heritage speaker groups, however, Spanish proficiency was a stronger predictor of subjunctive knowledge than age of acquisition of English, a finding with implications for both heritage language research and pedagogy.