Date of Award

May 2022

Degree Type


Degree Name

Doctor of Philosophy



First Advisor

Sandra Liliana Pucci

Committee Members

Sandra Liliana Pucci, Fred R Eckman, Garry Davis, Hamid Ouali


Bilingualism, Heritage Language, Language Acquisition, Morpho-syntax (subject-verb agreement), Nominal Morphology (plural formation), Verbal Morphology (light-verb constructions)


There is a growing body of research from various perspectives in heritage language (henceforth HL) acquisition as an emerging field. Some studies proposed that HL acquisition is a differential acquisition compared with the baseline language (i.e., the language spoken by the parents or caregivers) (Kupisch & Rothman, 2018; Dubiel & Guilfoyle, 2021; Makarova & Terekhova, 2021; Caloi & Torregrossa, 2021; Nagy, 2021), while some other studies focus on a comparison of heritage speakers (henceforth HSs) with monolingual speakers and suggest that HSs acquisition of the baseline language is either incomplete, deficient, or arttrided (Benmamoun, Montrul, & Polinsky, 2013; Montrul, 2005, 2008, 2016, 2018; Polinsky, 2008, 2011). While there is abundant research on HL and HSs’ acquisition, Iranian HSs have rarely been studied. There is no research- to the best of our knowledge- on the linguistic system of Persian/ Farsi HL and the acquisition of Persian/Farsi HSs. Therefore, this dissertation- for the first time- investigates the acquisition of Persian (Farsi) (It is noteworthy that the correct term is “Modern Pahlavi or Iranian language”; however, due to the popularity and historical use of the terms “Persian (Farsi)”, these terms are used in this dissertation.) HL as an independent variety in the United States and delineates its unique features via new perspectives on HSs and their acquisition. To preclude discrepancies and fallacies of HL acquisition and to focus on the language competence of more homogenous HSs, this study focuses on active HSs, namely those who have acquired an HL and are using it actively in daily communication.

This dissertation explored the Persian/Farsi HSs’ acquisition of nominal morphology, represented by plural formation, verbal morphology, represented by light verb constructions, and morpho-syntax, represented by subject-verb agreement (SVA). There were six main questions and hypotheses in this study, and to investigate the independent properties and features of the acquisition of Persian HL in the United States, 10 Persian HSs, including 5 children (mean age 13.4 years (SD=5.59) and 5 adults (mean age 29.2 years (SD=4.96) were selected by the convenience sampling method. The data were collected through various experimental procedures, including personal interviews, and questionnaires for linguistic background and demographic information. The consistency of HSs’ production and judgment was investigated via oral production, written tasks, and Grammaticality Judgment Test/ Correction (GJT/C) for each linguistic structure.

Light-verb construction results revealed that HSs predominantly produce similar constructions (82.85% (oral), 95% (written)) to the “Tehrani” dialect which is the dominant dialect of participants’ parents and caregivers. However, they also showed unique features such as using some innovative light verb constructions (i.e., an English preverbal element with a Persian light verb) and unique light verbs that are not present in the monolingual Persian language system. Likewise, plural formation results showed that HSs produce plurals significantly similar to (98.03% (oral), 82.16% (written)) the “Tehrani” dialect. Nonetheless, they produced some innovative and unique plural forms that are not used in the monolingual baseline language.

SVA results indicated interesting findings that HSs’ SVA is modality-constrained, meaning that it changes in oral and written production. In oral modality, HSs’ SVA rules are the same as Classic Persian (CP), meaning that SVA for the inanimate plural subjects is not optional, and HSs use singular verbs predominantly for the inanimate plural subjects. However, in the written modality, HSs’ SVA rules are the same as the SVA rules of Modern Standard Persian (MSP), meaning that SVA is optional, and HSs use either singular or plural verbs for the inanimate plural subjects.

GJT/C results also confirmed the consistency in the production of child and adult HSs and the harmony between their production and judgment. This study illustrated the findings via 25 evident features of systematicity, productivity, and dynamism to demonstrate the unique characteristics of the Persian HL system. Overall, the findings supported the hypotheses and corroborated that Persian (Farsi) HL in the United States is a distinct variety of Persian that though having much in common with other varieties of Persian, has some unique features too.

This study argues that the cross-linguistic influence of English as the dominant language of the sociolinguistic context could account for some of the findings. Moreover, with a new viewpoint, this study highlighted that the novel and innovative forms in HS’s production are the results of the dynamic interaction in an “interlanguage system” between colloquial Persian, as the HL, and MSP, as the dominant language in the diglossic context. This study advocated that interlanguage could be extended from a concept in the second language acquisition to an independent system in bilinguals’ acquisition. However, using the term “Interlanguage” in this study does not signify that HL acquisition and second language acquisition are the same. In other words, using the term “Interlanguage” in this study, does not make HL acquisition be on par with second language acquisition.

Looking at the findings through a different lens, this study suggested that some of the novel examples or patterns in HSs’ production are the result of the poverty-of-stimulus effect, meaning that neither the first language (L1) grammar nor the second language (L2) surface patterns can account for some properties of the interlanguage system (Schwartz & Sprouse, 2000). The emergence of poverty-of-stimulus examples in the HSs’ production provides support for the productivity of HSs’ language system. Consequently, it verifies that HL is an independent language system that might have direct access to Universal Grammar (UG).

Overall, relying on the results of this study and evident examples of the poverty-of-stimulus effect, productivity, systematicity, and consistency in the production and judgment of Persian (Farsi) HSs in the United States, this study concluded that the Persian HL is an independent variety of Persian that has its unique features. Also, with a new stance, this study highlighted that accepting an HL as an independent variety entails that we should stop labeling HSs’ acquisition as a deficient or partial acquisition, and instead, we should focus on describing the unique features of HSs’ acquisition. Despite many studies that consider HL acquisition an incomplete acquisition or attrition, the results of this study demonstrated that not only does the HL system work as a fully functioning system with its unique features, but also evident innovative patterns indicate that the HL system is a productive and dynamic system. Therefore, this study suggests that the divergence from the standard variety in a diglossic context does not corroborate competence deficiencies, what some researchers call “incomplete acquisition”, rather it implies developing fully in a different context.

By investigating the acquisition of Persian (Farsi) HL, one of the least studied languages, for the first time, this study informs linguistic theories and contributes to constructing the theoretical background of Persian HL acquisition and adds to the linguistic diversity of bilingualism and HL research. It also contributes to a better understanding of the linguistic system of HSs in general and in the multilingual, and diverse society of the United States in particular and lays the groundwork for further research.

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