Aims and objectives/purpose/research questions: This study investigated three key issues in heritage language research. Previous research shows heritage language speakers have an advantage on tasks of oral production compared to L2 speakers who instead perform better on written tasks requiring use of metalinguistic skills. Furthermore, both L2 and heritage speakers are claimed to have a yes-bias towards retaining ungrammaticality in grammaticality judgement tests (GJTs). Finally, the morphological domain has been shown to be as problematic for heritage language speakers as L2 speakers, but research in lesser-known languages is needed.

Design/methodology/approach: Adult L1, L2, and heritage language speakers of Italian were compared on an oral priming task and timed GJT. Both accuracy and response times were elicited from the latter test. The forms investigated were object and si-passive pronouns which lack corresponding forms in Swedish, the dominant language of the bilingual groups.

Data and analysis: Mixed-effects regression was modelled to accuracy on the priming and GJT and response time data from the GJT. In contrast, a d-prime analysis was used to measure the degree of sensitivity to grammaticality and bias towards correct and incorrect answers in the GJT.

Findings/conclusions: Overall, the two bilingual groups performed quite similarly across the measures tested. All three groups show high sensitivity to grammaticality and a very similar bias for yes-answers on both grammatical and ungrammatical items.

Originality: The study is the first to employ a d-prime analysis to explore in greater detail the differences in knowledge of grammaticality between heritage, L2, and monolingual populations. It also presents a brief review of the limited existing research in heritage Italian.

Significance/implications: Any advantages by task for either bilingual group level out by the time high proficiency levels are reached but may be associated with literacy levels when metalinguistic skills are measured. The yes-bias is likely a characteristic intrinsic to GJTs rather than a peculiarity of bilingual speaker knowledge. Morphology is problematic also for heritage speakers of lesser-known languages.

Conversely to plenty of studies describing how L1 transfer affects L2 systems, where the two grammars, L1/L2, often only come to interact later in life, less is known of dominant language transfer in heritage language grammars. Unlike in L2 speakers, the dominant language of the heritage speaker potentially affects its weaker language already from childhood. Evidence of dominant language transfer, however, exists in language production studies focusing on syntax. Therefore, an oral structural priming task was employed to compare transfer effects in advanced Swedish speakers of Italian and early heritage Italian speakers dominant in Swedish. Intrinsic to this comparison is the Basic Continuity hypothesis (Romano 2018), which proposes that highly proficient L2 speakers integrate semantic and syntactic information relevant to an L2 property lacking in the L1 in native-like ways. Results showed that heritage and L2 grammars are similarly impervious to transfer effects and coordinate structural and lexico-semantic information in native-like ways, consistent with the Basic Continuity. Divergence from native controls is shown to be remarkably compatible with monolingual grammars at earlier developmental stages.

Accuracy in use of inflection is a defining feature of native and non-native academic writing. In EAP contexts, non-native texts are dominated by errors in use of tense and agreement, despite accuracy being an important element of text complexity and EAP teaching and assessment. An open question is to what degree the absence of inflection in the EAP learner's L1 resembling English tense and agreement is associated with inaccuracy. This study examined verb form errors in the EAP writing of L1 Chinese learners and assessed the degree to which errors stem from the absence of similar inflection in the L1. The use of three forms that are especially important in native and non-native academic writing, tense/agreement, passives, and modals, was analysed. These forms were especially relevant due to the fact that only modals and passives have cognates in English. Analyses show errors were most frequently omission and misuse. Errors with tense/agreement outnumbered both passives and modals, suggesting the former are especially difficult to master as cognate forms are absent in the L1. Furthermore, similar rates of misuse and omission were found across passives and modals, suggesting these forms are attainable. Implications for teacher-training, materials development, and error-correction are discussed. 

To what extent can second language (L2) speakers acquire a syntactic representation for an L2 structure absent in the first language (L1)? Findings from L2 structural priming studies are in conflict inasmuch as evidence for and against continuity between L1 and L2 sentence production has been shown. Furthermore, previous investigations have not adequately controlled for well-known animacy effects on choice of syntactic frames. I address the conflict of views in the field via three experiments of structural priming with native, Chinese, and Turkish speakers of English by means of an oral sentence-recall production task. The structure tested, the English genitive alternation, is subject to animacy effects as in the waiter’s photo / the photo of the waiter. Chinese and Turkish have no equivalent to English of genitives nor animacy effects in their genitive structure. Experiment 1 showed priming within-L1 English and found evidence of an animacy effect, albeit only numerical. Likewise, Experiment 2 showed priming within-L2 English and found the L1 Chinese were similarly susceptible to animacy effects. Experiment 3 also showed clear within-L2 English priming in Turkish speakers but the effects of animacy differed from the other groups. I argue the similarities between the native and L2 groups to constitute grounds for a basic continuity in L1 to L2 production.

Key accounts of morphological variability in L2 acquisition posit either deficits in the representation of abstract morphosyntactic features or the mapping between morpho-phonological forms and syntactic features due to computational limitations. This study extends previous research to L2 Italian, a richly inflected language. The production and grammatical intuitions of suppletive and affixal verb inflection were elicited from a cross-section of instructed adult L2 learners with L1 Spanish and L1 English. Although a clear production-intuition gap was found, supporting computational views, a strong regularity in the degree of variability across test conditions, L1s, and proficiency levels was also attested, supporting representational accounts. The findings suggest morphological development in L2 Italian is consistent with structure-building models that assume no L1 transfer of functional features. Imperative verb forms in L2 Italian are proposed as defaults equivalent to the bare verb forms of L2 English and non-finite defaults of L2 French and German.