Anne Salazar Orvig

Geneviève De Weck

Rouba Hassan

Annie Rialland

Anne Salazar Orvig

A dialogical approach to the acquisition and usage of referring expressions

Keywords: dialogical approach, reference, referring expressions, activities, dialogue, social settings, scaffolding, morphological and syntactic development

This chapter gives a general overview of the dialogical, theoretical, and methodological framework of the studies presented in the book, and the implications of that framework for understanding the acquisition of referring expressions and children's early skills in this domain. Section 1 considers the formal aspects of children's acquisition of the relevant morphological paradigms (mainly pronouns, and including fillers) in relation to certain aspects of syntactic development. Section 2 is devoted to studies on reference and referential strategies in children. After dealing with some discrepant results, we focus on the dialogical foundation of reference. As a whole, the chapter builds up a rationale for a multidimensional approach, considering the interaction of formal and functional factors in the acquisition of referring expressions, and, more generally, the way meaning is constructed in socially situated interactions driven by activities and scaffolded by adults. Section 3 presents the methodological choices this approach entails. Section 4 introduces the issues tackled by the nine studies presented in the book.

The acquisition of reference and referring expressions is a challenging issue for developmental studies because it simultaneously involves both the formal and functional aspects of language acquisition. On the one side, the acquisition of referring expressions corresponds to the construction of grammatical paradigms, such as pronouns, inflections, and determiners, and to the acquisition of syntax, such as the use of syntactic arguments. On the other side, the acquisition of referring expressions requires the child to gradually master both the referential values of linguistic devices and their conditions of use (for several reviews, see Serratrice & Allen, 2015). In the studies presented in this book, we deal with the acquisition and use of referring expressions in French 1 from an interactionist and dialogical perspective, at the crossroads of several converging approaches. The interactionist approach stems from the pioneering work by Vygotsky (1934Vygotsky ( /1962) ) developed by [START_REF] Bruner | From communication to language: a psychological perspective[END_REF][START_REF] Bruner | The formats of language acquisition[END_REF][START_REF] Bruner | Child's talk: learning to use language[END_REF], according to which verbal and non-verbal interactions -and, more specifically, the mediating role of caregivers and their scaffolding -are the context and the driving force of cognitive development and language acquisition. We propose a dialogical approach to this interaction process. Inspired by Vološinov (1929Vološinov ( /1986) ) and Bakhtin (1975Bakhtin ( /1982Bakhtin ( , 1979Bakhtin ( /1986), a dialogical approach to language acquisition focuses not only on the interactional dimension but also on the joint discursive construction of a common space of meanings (see [START_REF] Bronckart | Interactions, discours, significations[END_REF][START_REF] Bronckart | Activité langagière, textes et discours. Pour un interactionnisme sociodiscursif[END_REF][START_REF] Clark | Using language[END_REF][START_REF] François | Problèmes et esquisse méthodologique[END_REF][START_REF] François | Pratiques de l'oral. Dialogue, jeu et variations des figures du sens[END_REF]. According to this perspective, "the child does not move from language structures to speech, but from the other's utterances to his/her own utterances: in short (...) his/her discourse is essentially dialogical" (François, 1988: 17, our translation) 2 . Our 1 This book reports the main results of a research program called the "Acquisition of referring expressions in dialogue: a multidimensional approach (DIAREF, funded by the French National Research Agency, ANR 09-ENFT-055). 2 " … l'enfant ne va pas des structures de la langue à la parole, mais des énoncés de l'autre aux énoncés de soi : bref (...) son discours est essentiellement dialogique". contention is that children grasp language structures through discourse, and, more precisely, through the experience of speech genres and/or language games [START_REF] Wittgenstein | Philosophical investigations[END_REF]. We also contend that there is a mutual influence between language games, which support language acquisition, and the development of specific dialogical skills, which allow the child to participate in the joint process of language construction. This position is close to Tomasello's socio-pragmatic perspective [START_REF] Tomasello | The cultural origins of human cognition[END_REF] and to Nelson's functional approach [START_REF] Nelson | Young minds in social worlds: Experience, meaning, and memory[END_REF].

Our first aim is to thoroughly describe French-speaking children's repertoire and use of referring expressions, mostly in typically developing children (TD) at different ages, but also in children with developmental language disorders (DLD). Beyond this first description, our aim is to enhance the understanding of the conditions that promote the acquisition of the forms, uses and functions of referring expressions. Among the possible conditions, our theoretical perspective leads us to focus on the role of socio-discursive context, and of dialogue in toddlerhood and early school age.

This introductory chapter first addresses some of the main topics in reference and referring expressions, with a particular attention to the role of dialogue in understanding the development of referential skills and strategies (Sections 1 and 2). We then present the methodological choices that stem from our theoretical options (Section 3). The last section presents the way the chapters deal with the main issues addressed in our research program (Section 4).

1. Formal aspects of the acquisition of the referring expressions: What is involved?

Referring expressions do not constitute a single grammatical category. They correspond to the set of linguistic expressions that can potentially be used to refer to what [START_REF] Lyons | Semantics[END_REF] called first-order entities (things, animals, persons, etc.) and to abstractions, ideas, discourses, and processes that pertain to Lyon's second-and third-order entities. Referring expressions correspond to nominal expressions, such as proper nouns, pronouns (personal, demonstrative, indefinite, etc.), and definite, indefinite, demonstrative, and possessive noun phrases. Their acquisition covers a complex range of formal processes that we quickly summarize here before moving on to its functional aspects in Section 2.

The emergence of referring expressions is interwoven with grammatical and syntactic development. Even if the very first referential acts are non-verbal [START_REF] Bruner | From communication to language: a psychological perspective[END_REF] -as infants communicate with their interlocutors about entities of the external world through vocalizations, gazes and gestures -the beginning of linguistic development contributes a new dimension to this emerging skill. Their first words give children the opportunity to encode entities and/or to make predications about them. With first word combinations comes the development of grammatical morphemes (in French, determiners and pronouns), which provide new means of expressing entities and/or indicating their referential status. These new referential possibilities appear as children begin to build their first syntactic relations and grammatical paradigms emerge. In addition, the construction of the paradigms of referring expressions contributes to the construction of the grammatical categories of nouns and verbs [START_REF] Bassano | Early development of nouns and verbs in French: Exploring the interface between lexicon and grammar[END_REF][START_REF] Veneziano | Noun and Verb categories in acquisition: evidence from fillers and inflectional morphology in French-acquiring children[END_REF], but it is also because nouns are mainly used to refer, and verbs to predicate, that their meanings need to be specified by means of referring expressions [START_REF] Tomasello | Constructing a language. A usage-based theory of language acquisition[END_REF].

The acquisition of determiners and pronouns are dependent on phonological and prosodic development. For instance, some of the consonants they contain (for example /l/ for definite determiners and third-person pronouns or /ʒ/ for first-person pronouns) are not among the consonants that children acquire first [START_REF] Rose | French speech acquisition[END_REF][START_REF] Yamaguchi | Parcours d'acquisition des sons du langage chez deux enfants francophones[END_REF].

Determiners and pronouns in prelexical position occur in a weak unstressed position, which make them less phonologically salient. Furthermore, prosodic constraints (such as the preferred iambic-foot structure, i.e., an unstressed syllable preceding a stressed syllable) can account both for the omission of prelexical morphemes in bisyllabic words and for the production of additional syllables (fillers) in monosyllabic or trisyllabic words [START_REF] Demuth | Prosodic constraints on morphological development[END_REF][START_REF] Demuth | Prosodically-conditioned variability in children's production of French determiners[END_REF][START_REF] Veneziano | The changing status of 'filler syllabes' on the way to grammatical morphemes[END_REF]. More specifically, fillers appear to be transitional phenomena that undergo two stages: a pre-morphological stage where they are determined by prosodic constraints, and a proto-morphological stage where they share distributional properties with grammatical morphemes and become specific to the nominal and verbal paradigms [START_REF] Bassano | The acquisition of nominal determiners[END_REF][START_REF] Peters | Filler syllabes: what is their status in emerging grammar[END_REF][START_REF] Veneziano | The changing status of 'filler syllabes' on the way to grammatical morphemes[END_REF], Veneziano, 2017, inter alia). However, one question that has seldom been raised is whether the distributional properties of fillers also reflect children's sensitivity to the functional features of pronouns and determiners.

At the first stages of grammatical development, adult-like morphemes alternate with fillers and omissions or null forms. For determiners, definite forms emerge first, followed by indefinite ones. Possessive, and then demonstrative determiners are acquired later. Singular and masculine forms seem to be mastered before feminine and/or plural ones [START_REF] Bassano | The acquisition of nominal determiners[END_REF][START_REF] Mené | L'acquisition d'un paradigme: éclairage multidimensionnel sur la mise en place des déterminants chez quatre enfants entre 1;6 et 3[END_REF][START_REF] Nashawati | Le développement des expressions référentielles chez le jeune enfant: noms et pronoms dans des dialogues mère-enfant[END_REF][START_REF] Rozendaal | A cross-linguistic investigation of the acquisition of the pragmatics of indefinite and definite reference in two-year-olds[END_REF]. The acquisition of their semantic values is usually considered to be a long process (Karmiloff-Smith, 1979, inter alia). 3 Concerning pronouns, the landscape is more complex because the modalities and rhythms of acquisition depend on factors as diverse as the type of pronoun (personal vs. demonstrative), their morphosyntactic status (in French, a non-null-subject language, subject and object pronouns are clitics) or the grammatical person (third vs. first or second). Most studies on French [START_REF] Caët | Référence à soi et à l'interlocuteur chez des enfants francophones et anglophones et leurs parents[END_REF][START_REF] Hamann | On the acquisition of subjects and object clitics in French[END_REF][START_REF] Morgenstern | Un je en construction[END_REF][START_REF] Salazar Orvig | Dialogical beginnings of anaphora: the use of third person pronouns before the age of 3[END_REF] show that the demonstrative pronoun "ça" is acquired earlier than personal pronouns, which emerge around the age of two. [START_REF] Jakubowicz | Hypothèses psycholinguistiques sur la nature du déficit dysphasique[END_REF]Rigaut (1997, 2000) noted that in children aged 2;0 to 2;7 most utterances include a clitic pronoun in the subject position whereas object clitic pronouns are acquired later. On the other hand, there is no consensus regarding the order of acquisition for grammatical persons (third vs. first and second or viceversa) because clitic pronouns frequently alternate with omissions and fillers for a lengthy period of time.

Furthermore, pronouns are a zone of fragility for children who have developmental disorders.

Salazar Orvig and de Weck (2013) showed that children with DLD aged 5-7 have a narrower range of pronouns than do typically developing children at the same age, as far as types (personal, relative, demonstrative, etc.) and forms are concerned (a smaller variety of forms in each type). The capabilities and difficulties of children with DLD in using these grammatical morphemes provide evidence of the interplay between these different linguistic dimensions. For instance, for [START_REF] Parisse | The interplay between phonology and syntax in Frenchspeaking children with specific language impairment[END_REF], a phonological disorder can account for the omission, distortion, and/or replacement of short grammatical morphemes (pronouns, determiners), which have weak phonological saliency. However, object clitic pronouns in French occur in preverbal position, and are more frequently omitted than subjects, which constitutes evidence against this hypothesis. According to [START_REF] Jakubowicz | Hypothèses psycholinguistiques sur la nature du déficit dysphasique[END_REF], these omissions can be accounted for in morphosyntactic terms, as part of the difficulties affecting the verb.

The construction of these paradigms, omissions, and errors in the use of determiners and pronouns are also tightly linked to the development of syntactic structures (for reviews, see [START_REF] Allen | Formalism and functionalism working together? Exploring roles for complementary contributions in the domain of child null arguments[END_REF][START_REF] Ambridge | Child language acquisition: Contrasting theoretical approaches[END_REF][START_REF] Guasti | Language acquisition. The growth of grammar[END_REF]. Generativist-nativist approaches propose accounts in terms of pre-existing abstract categories and grammar, and do not necessarily consider any functional aspects. By contrast, among the functionalist approaches, the Preferred Argument Structure framework (Du Bois, Kumpf & Ashby, 2003) allows null subjects to be accounted for at the interface between syntax and pragmatics [START_REF] Allen | A discourse-pragmatic explanation for argument representation in child Inuktitut[END_REF][START_REF] Clancy | Preferred argument structure in Korean acquisition[END_REF]. More recently, usage-based approaches [START_REF] Behrens | The input-output relationship in first language acquisition[END_REF][START_REF] Lieven | Input and first language acquisition: Evaluating the role of frequency[END_REF][START_REF] Tomasello | Constructing a language. A usage-based theory of language acquisition[END_REF] have shown that children tend to take up forms and constructions in an itembased way before being able to process them through a grammar (Akthar, 1999;[START_REF] Ibbotson | The role of pronoun frames in early comprehension of transitive constructions in English[END_REF]Lieven, 2014, inter alia). Therefore, usage-based approaches consider that grammatical morphemes such as pronouns or determiners are first experienced in the context of rote-learned holophrases (I-want-it) or lexically specific slots and frame patterns (I'm Xing it, That's a Y), which are very frequent in adult input [START_REF] Ambridge | A constructivist account of child language acquisition[END_REF]. Within this framework, omissions or errors are accounted for on the basis of the distributional features of the input. Therefore, the construction of grammatical categories, syntactic structures, and functions is the result of a long, irregular process of analogy, generalization, and abstraction, which takes place throughout childhood [START_REF] Ambridge | A constructivist account of child language acquisition[END_REF][START_REF] Tomasello | Constructing a language. A usage-based theory of language acquisition[END_REF].

Thus, any study of the acquisition of referring expressions must consider various aspects: the fact that grammatical categories and syntactic relations alike are still being formed, the fact that this process relies on how the child takes up what is present in the adult's input (and therefore the importance of frequency; see [START_REF] Ambridge | The ubiquity of frequency effects in first language acquisition[END_REF], and the way the child grasps that input. This is true for the formal aspects of referring expressions; it is also true for their functional aspects, i.e., their usage in a diversity of communication contexts, to which we will turn now.

Reference and dialogue

In this section, we address the referential/pragmatic aspects of the acquisition of referring expressions. Section 2.1 provides an overview of reference acquisition that shows the heterogeneity of the findings. More detailed accounts can be found in various chapters of this book. Section 2.2 examines the way in which dialogue underlies reference and its acquisition, an issue that has not been thoroughly investigated in previous research.

Main studies on the acquisition of reference

Reference and referring expressions have been a constant concern in the field of language acquisition. Several lines of research have emerged since the beginning of pragmatic approaches to language development in the mid-seventies, when leading authors like Elinor Ochs, Patricia Greenfield, Elizabeth Bates, and Annette Karmiloff-Smith worked simultaneously on various interconnected issues such as presupposition [START_REF] Bates | Language and context: the acquisition of pragmatics[END_REF], informativeness [START_REF] Greenfield | Informativeness, presupposition and semantic choice in single-word utterances[END_REF]), referential values (Karmiloff-Smith, 1979), and discourse and dialogue continuity [START_REF] Ochs Keenan | Coherency in children's discourse[END_REF][START_REF] Ochs Keenan | Topic as discourse notion: a study of topic in the conversations of children and adults[END_REF].

Theoretically speaking, the field was nourished by various philosophical, linguistic, and psycholinguistic traditions dealing with reference in adult usage. Among the many concerns in the field, we can mention the functions of referring expressions (anaphoric vs. deictic [START_REF] Lyons | Semantics[END_REF][START_REF] Lyons | Deixis and anaphora[END_REF], the status of referents and the given/new opposition [START_REF] Chafe | Givenness, contrastiveness, definiteness, subjects, topics, and point of view[END_REF][START_REF] Haviland | What's new? Acquiring new information as a process in comprehension[END_REF], discursive construction and cohesion (Halliday & Hasan, 1976), the utterance information structure and its relation to text coherence [START_REF] Chafe | Givenness, contrastiveness, definiteness, subjects, topics, and point of view[END_REF]Givón, 1983[START_REF] Givón | Coherence in text vs. coherence in mind[END_REF], the interface between syntax and pragmatics (Du Bois et al., 2003), and sensitivity to the interlocutor's perspective and shared knowledge [START_REF] Ariel | Referring and accessibility[END_REF][START_REF] Ariel | Accessing noun-phrase antecedents[END_REF][START_REF] Chafe | Givenness, contrastiveness, definiteness, subjects, topics, and point of view[END_REF][START_REF] Chafe | Cognitive constraints on information flow[END_REF][START_REF] Clark | Contributing to discourse[END_REF][START_REF] Clark | Referring as a collaborative process[END_REF][START_REF] Gundel | Reference and accessibility from a givenness hierarchy perspective[END_REF][START_REF] Gundel | Cognitive status and the form of referring expressions in discourse[END_REF].

Currently, the main issue for most authors concerns the discursive and pragmatic conditions under which children appropriately select a referring expression among the possible choices in their language (noun phrases, demonstrative pronouns, personal pronouns, null forms, etc…) to encode a referent, and how they identify these conditions. Some studies have explored comprehension and production of noun phrases in referential communication activities [START_REF] Davies | Over-informative children: Production/comprehension asymmetry or tolerance to pragmatic violations?[END_REF][START_REF] Whitehurst | The development of communication: a functional analysis[END_REF]; inter alia, for a review, see [START_REF] Graf | The production and comprehension of referring expressions[END_REF]. Others, based on the functionalist Preferred Argument Structure framework (Du Bois, Kumpf & Ashby, 2003), have shown that a discourse-pragmatic foundation of grammar accounts for an initial syntactic issue, i.e., omissions in early utterances in both null and nonnull subject languages [START_REF] Allen | A discourse-pragmatic explanation for argument representation in child Inuktitut[END_REF][START_REF] Allen | Preferred argument structure in early Inuktitut spontaneous speech data[END_REF][START_REF] Clancy | Preferred argument structure in Korean acquisition[END_REF][START_REF] Clancy | Discourse motivations for referential choice in Korean acquisition[END_REF][START_REF] Clancy | The lexicon in interaction: Developmental origins of preferred argument structure[END_REF].

Another set of studies have dealt more specifically with the development of discursive skills.

Reference was considered through the lens of text structure, cohesion, or coherence issues. This led to studies focusing on the information structure and the management of topics [START_REF] Bamberg | The acquisition of narratives: learning to use language[END_REF][START_REF] Benoit | Formal coherence production in children's discourse[END_REF][START_REF] De Weck | La cohésion dans les textes d'enfants. Etude du développement des processus anaphoriques[END_REF][START_REF] Hickmann | Children's discourse: person, time and space across languages[END_REF][START_REF] Hickmann | Cohesion and anaphora in children's narratives: a comparison of English, French, German and Mandarin Chinese[END_REF][START_REF] Jisa | Increasing cohesion in narratives: a developmental study of maintaining and reintroducing subjects in French[END_REF][START_REF] Karmiloff-Smith | A functional approach to child language: a study of determiners and reference[END_REF], 1985;[START_REF] Kern | Comment les enfants jonglent avec les contraintes communicationnelles, discursives et linguistiques dans la production d'une narration[END_REF][START_REF] Kern | Effet du type de support imagé sur la production du récit chez l'enfant[END_REF][START_REF] Liles | Cohesion in the narratives of normal and language-disordered children[END_REF][START_REF] Peterson | A longitudinal analysis of young children's cohesion and noun specification in narratives[END_REF]. These studies resulted in divergent or even contradictory outcomes.

The very first observations and qualitative studies on naturally occurring interactions [START_REF] Greenfield | Informativeness, presupposition and semantic choice in single-word utterances[END_REF][START_REF] Greenfield | The structure of communication in early language development[END_REF][START_REF] Ochs Keenan | Coherency in children's discourse[END_REF][START_REF] Ochs Keenan | Topic as discourse notion: a study of topic in the conversations of children and adults[END_REF] tended to put forward children's early skills, whereas studies on experimental settings and/or on elicited narratives highlighted a gap between early deictic strategies and more mature anaphoric ones [START_REF] De Weck | La cohésion dans les textes d'enfants. Etude du développement des processus anaphoriques[END_REF][START_REF] Hickmann | The development of discourse cohesion: some functional and crosslinguistic issues[END_REF]Karmiloff-Smith, 1985, inter alia).

However, within the past 25 years, since Clancy's studies on Japanese and Korean [START_REF] Clancy | Preferred argument structure in Korean acquisition[END_REF][START_REF] Clancy | Referential strategies and the co-construction of argument structure in Korean acquisition[END_REF][START_REF] Clancy | Discourse motivations for referential choice in Korean acquisition[END_REF], the increase in quantitative studies on mother-child interactions at the onset of language development, and their gradual theoretical convergence towards cognitive approaches to reference, with the notions of accessibility [START_REF] Ariel | Referring and accessibility[END_REF][START_REF] Ariel | Accessing noun-phrase antecedents[END_REF] or givenness [START_REF] Gundel | Cognitive status and the form of referring expressions in discourse[END_REF] 4 , brought about a substantial change in the conceptualization of children's discursive productions and their uses of referring expressions (see reviews in [START_REF] Allen | The role of cognitive accessibility in children's referential choice[END_REF][START_REF] Graf | The production and comprehension of referring expressions[END_REF][START_REF] Hickmann | From early to late mastery of reference. Multifunctionality and linguistic diversity[END_REF][START_REF] Salazar Orvig | Reference and referring in first language acquisition[END_REF]. These studies, which have investigated a wide range of languages presenting diverse morphological and syntactic features, converged to confirm that young children are sensitive to a referent's accessibility or givenness. Through their nascent linguistic competence, children very soon build a linguistic contrast between weak forms (be they null forms or clitic pronouns, depending on the language) and strong forms (lexical forms, stressed pronouns, dislocated and topicalized constructions, etc.). Some studies (Le [START_REF] Mené | L'acquisition d'un paradigme: éclairage multidimensionnel sur la mise en place des déterminants chez quatre enfants entre 1;6 et 3[END_REF][START_REF] Rozendaal | A cross-linguistic investigation of the acquisition of the pragmatics of indefinite and definite reference in two-year-olds[END_REF]Salazar Orvig et al., 2013) have also brought out an early contrast between definite (presupposing) and indefinite determiners in referential uses of noun phrases.

However, other studies conducted in experimental settings [START_REF] Matthews | The effect of perceptual availability and prior discourse on young children's use of referring expressions[END_REF]Serratrice, 2008, inter alia) and studies on narrative tasks [START_REF] Hickmann | Children's discourse: person, time and space across languages[END_REF][START_REF] Jisa | Increasing cohesion in narratives: a developmental study of maintaining and reintroducing subjects in French[END_REF][START_REF] Jisa | Promoting patients in narrative discourse: A developmental perspective[END_REF][START_REF] Kail | French children's ability to introduce referents in narratives as a function of mutual knowledge[END_REF], inter alia) nevertheless showed that full mastery of reference is a gradual and long process. For instance, in experimental or narrative monological contexts, younger children might be insufficiently informative (using pronouns, presupposing NPs or unmodified NPs) when introducing a referent, and when referring to an entity not perceptually available or potentially ambiguous to their interlocutor. For French in particular (de [START_REF] De Weck | La cohésion dans les textes d'enfants. Etude du développement des processus anaphoriques[END_REF][START_REF] De Weck | How do French-speaking children with specific language impairment first mention a referent in storytelling? Between reference and grammar[END_REF][START_REF] Kail | French children's ability to introduce referents in narratives as a function of mutual knowledge[END_REF], children generally do not introduce referents with indefinite noun phrases before the age of 6-7 years. In English, though, it seems that the predominance of indefinite noun phrases in first mentions of referents begins earlier [START_REF] Colozzo | The interplay of referential function and character primacy on referring expressions in children's narratives[END_REF]. In contrast, for subsequent mentions, children mainly use personal pronouns, which tend then to have an anaphoric value [START_REF] Akinci | La référence aux participants dans les narrations[END_REF][START_REF] De Weck | La cohésion dans les textes d'enfants. Etude du développement des processus anaphoriques[END_REF][START_REF] Hickmann | Children's discourse: person, time and space across languages[END_REF][START_REF] Karmiloff-Smith | Language and cognitive processes from a developmental perspective[END_REF][START_REF] Kern | Contexte et acquisition du langage: un cas de narration[END_REF], and to be used mostly for the main characters of the story [START_REF] Bamberg | The acquisition of narratives: learning to use language[END_REF][START_REF] De Weck | La cohésion dans les textes d'enfants. Etude du développement des processus anaphoriques[END_REF]Salazar Orvig & de Weck, 2013;[START_REF] Vinel | Comment des adultes et des enfants, âgés de 3 à 6 ans, racontent ensemble des histoires en situations familiales et scolaires[END_REF]. Differences have been observed across genres in the "density"5 of referring expressions [START_REF] De Weck | La cohésion dans les textes d'enfants. Etude du développement des processus anaphoriques[END_REF], their grammatical category [START_REF] De Weck | La cohésion dans les textes d'enfants. Etude du développement des processus anaphoriques[END_REF][START_REF] De Weck | Anaphoric procedures in four text types written by children[END_REF][START_REF] Pellegrini | Context in text: The development of oral and written language in two genres[END_REF], and their functions [START_REF] Mazur Palandre | Information flow across modalities and text types[END_REF]. The differences vary according to the child's age until adolescence. However, between ages 10 and 11, children's uses of referring expressions come closer to those of adults when the narrative discourse contains few referential chains and/or clearly contrasted referents (e.g., [START_REF] Hickmann | Children's discourse: person, time and space across languages[END_REF][START_REF] Jisa | Increasing cohesion in narratives: a developmental study of maintaining and reintroducing subjects in French[END_REF].

When we look into DLD children's uses, we do not observe the same tendencies. Their use of referring expressions has mainly been examined in narratives. Research shows that, compared to typically developing same-age peers, DLD children produce more ambiguous referring expressions (especially null forms and undefined forms), and make certain, specific errors up until a later age. This is true both for first mentions (e.g., [START_REF] De Weck | How do French-speaking children with specific language impairment first mention a referent in storytelling? Between reference and grammar[END_REF][START_REF] De Weck | Troubles dysphasiques. Comment raconter, relater, faire agir à l'âge préscolaire[END_REF]Schelleter & Leinonen, 2003;[START_REF] Schneider | Who does what to whom: Introduction of referents in children's storytelling from pictures[END_REF] and subsequent mentions [START_REF] De Weck | Les troubles pragmatiques et discursifs dans la dysphasie[END_REF][START_REF] Liles | Cohesion in the narratives of normal and language-disordered children[END_REF][START_REF] Paul | Narrative development in late talkers: Early school age[END_REF]. However, like their typically developing peers they preferably use noun phrases for first mentions (de [START_REF] De Weck | How do French-speaking children with specific language impairment first mention a referent in storytelling? Between reference and grammar[END_REF]. The difficulties of DLD children have been observed up to adolescence [START_REF] Wetherell | Narrative in adolescent specific language impairment (SLI): a comparison with peers across two different narrative genres[END_REF].

Although the partially discrepant results of studies on young children in natural dialogues and studies on older children in narratives can be accounted for in terms of theory-based reasons (for example, textual/localist approaches following Halliday and Hassan, 1975, vs. cognitive approaches to reference inspired by [START_REF] Ariel | Accessing noun-phrase antecedents[END_REF][START_REF] Gundel | Cognitive status and the form of referring expressions in discourse[END_REF] or methodological reasons (e.g., the difference between ecological and experimental settings), they lead us to a reevaluation of the precocity of young children's pragmatic skills. The results have also revealed that the choice of referring expressions is affected by several interacting factors (such as animacy, subject function, topicality, and accessibility). At another level, we can mention speech genre -i.e. narratives or descriptions -and scripts, which determine the specific organization of characters and objects. Moreover, the relative weight of certain factors like syntactic functions, and referent animacy can override the referential status of the encoded entity [START_REF] Allen | Interacting pragmatic influences on children's argument realization[END_REF]Hickmann et al., 2015, inter alia). According to [START_REF] Hickmann | From early to late mastery of reference. Multifunctionality and linguistic diversity[END_REF], the crucial issue is the children's mastery of multifunctionality, which cannot show up at the early stages of language development due to the coalescence of different factors favoring adultlike uses of referring expressions. Uzundag & Küntay, 2018). However, other studies have also shown that cognitive skills are expressed jointly with sensitivity to adult models and feedback [START_REF] Matthews | Two-and four-year-olds learn to adapt referring expressions to context: Effects of distracters and feedback on referential communication[END_REF][START_REF] Matthews | How toddlers and preschoolers learn to uniquely identify referents for others: A training study[END_REF][START_REF] Uzundag | Children's referential communication skills: The role of cognitive abilities and adult models of speech[END_REF].

Concerning the social dimension of the construction of reference, data from naturally occurring interactions has shed a different light on children's productions. The next section addresses the contribution of dialogue to reference construction.

Reference in dialogue

The relevance of dialogue in reference construction has gradually gained ground in our understanding of reference in adult discourse, which moved slowly from a disembodied and monological approach [START_REF] Frege | Sense and reference[END_REF][START_REF] Frege | Sense and reference[END_REF] to more interactional concerns. Since [START_REF] Strawson | On referring[END_REF] view of reference as a speech act, this notion has evolved to include both the consciousness of the speaker, and his/her projection of the addressee's perspective and possibilities for retrieving the intended referent [START_REF] Ariel | Referring and accessibility[END_REF][START_REF] Ariel | Accessing noun-phrase antecedents[END_REF][START_REF] Chafe | Cognitive constraints on information flow[END_REF][START_REF] Gundel | Cognitive status and the form of referring expressions in discourse[END_REF]. In this view, referring expressions are seen as instructions that guide the addressee's interpretation. However, the addressee is still not always considered as an interlocutor. For instance, many experimental studies that have explored the uses of referring expressions (conducted either with adults or children) stage one-way interactions: the interlocutor is a passive hearer, or has only either a responding or an initiating role (e.g., asking a question, giving an instruction). There are two exceptions. First, H. Clark and his colleagues (H. [START_REF] Clark | Grounding in communication[END_REF][START_REF] Clark | Referring as a collaborative process[END_REF], inter alia) regard reference and common ground as being achieved collaboratively, which supposes that interlocutors mutually acknowledge their representation of the ongoing discourse. Second, in the framework of interactinal linguistics (B. [START_REF] Fox | Discourse structure and anaphora[END_REF][START_REF] Laury | Interaction, grounding and third-person referential forms[END_REF][START_REF] Laury | Subsequent-mention indefinites in American English conversation: cognitive and interactional factors[END_REF][START_REF] Pekarek Doehler | Anaphora in conversation: grammatical coding and preference organization[END_REF][START_REF] Pekarek Doehler | Emergent grammar for all practical purposes: the on-line formatting of left and right dislocations in French conversation[END_REF], reference and the cognitive status of referents are regarded not only as an interactional achievement but also as a resource for speakers, who, through their use of referring expressions, display their interpretation of the ongoing talk.

The next section addresses the relevance of interaction and dialogue for the construction of reference in children.

The dialogical roots of reference

Children's referential abilities are grounded in their early pre-linguistic communicative experience [START_REF] Bruner | From communication to language: a psychological perspective[END_REF]. A conception of reference as "a social act in which one person attempts to get another person to focus her attention on something in the world" (Tomasello, 1999: 97) implies two pre-conditions: (a) the achievement of a state of intersubjectivity between the child and his/her caregiver [START_REF] Trevarthen | Descriptive analyses of infant communicative behaviour[END_REF] and (b) the establishment of a joint attention space within this first intersubjective state [START_REF] Carpenter | Social cognition, joint attention and communicative competence from 9 to 15 months of age[END_REF]. The first, very early accomplishment of primary intersubjectivity is a condition for reference but it is not a sufficient one. Reference presupposes a triadic relation where the referent is under the mutual and joint attention of two participants. As mentioned before, this relation precedes the use of linguistic forms and is conveyed by non-verbal communication [START_REF] Bruner | From communication to language: a psychological perspective[END_REF][START_REF] Bruner | The formats of language acquisition[END_REF]. Before their first words, children experience exchanges with their interlocutor about a joint-focused referent through vocal non-word utterances [START_REF] Halliday | Learning how to mean[END_REF][START_REF] Ninio | Pragmatic development[END_REF] and gestures [START_REF] Liszkowski | 12-and 18-month-olds point to provide information for others[END_REF][START_REF] Liszkowski | Twelve-month-olds communicate helpfully and appropriately for knowledgeable and ignorant partners[END_REF][START_REF] Marcos | De la communication prélinguistique au langage[END_REF][START_REF] O'neill | Talking about "new" information: the given/new distinction and children's developing theory of mind[END_REF]. Reciprocally, in early joint-attention episodes, adults contribute to focusing, directing and maintaining children's attention using both gestural and discursive resources (E. [START_REF] Clark | Using speech and gesture to introduce new objects to young children[END_REF]. This early communication has two facets.

First, at around 9 months, infants begin to orient their interlocutors' attention to an object or an event, which becomes a joint focus of attention; this skill is the basis for deictic reference [START_REF] Bruner | From communication to language: a psychological perspective[END_REF]. Then, when they are involved in a joint-attention episode, infants contribute, with new elements (actions, information), to communication about in-focus referents; this skill is the basis for anaphoric reference.

Therefore, when they start producing their first words and first utterances, children have already mastered two "proto-referential" non-verbal functions: (1) attracting their interlocutor's attention to an object or an event, and thus establishing joint attention, (2) and taking part in a joint-attention episode. Few studies have dealt with the impact of joint attention on reference [START_REF] Skarabela | Signs of early social cognition in children's syntax: The case of joint attention in argument realization in child Inuktitut[END_REF]. Typically, the transition between from non-verbal to proto-verbal and then verbal resources has more often been explored for deictic reference [START_REF] Diessel | Demonstratives, joint attention, and the emergence of grammar[END_REF][START_REF] Ng | The role of gesture in referential communication. A developmental perspective[END_REF] than for proto-anaphoric reference.

Children's first one-word utterances display these proto-referential skills insofar as they "choose" words according to the referent's informational status [START_REF] Greenfield | Informativeness, presupposition and semantic choice in single-word utterances[END_REF][START_REF] Greenfield | The structure of communication in early language development[END_REF][START_REF] Greenfield | Why do children say what they say when they say it? An experimental approach to the psychogenesis of presupposition[END_REF]. The definition of informativeness (which has been revisited via the notion of accessibility; see [START_REF] Allen | Using corpora to examine effects in syntax[END_REF] was a matter of debate from the outset. [START_REF] Bates | Language and context: the acquisition of pragmatics[END_REF]

argued that the contrast between what is new (informative)

and what is presupposed in first speech acts is built solely on the child's attention. In contrast, Greenfield considered informativeness to depend on several features of the context shared by the child and the adult, such as possession, distance, agency, and previous mention. In dialogue, "the uncertain element expressed verbally by the child is (…) always 'new' information, as defined by [START_REF] Haviland | What's new? Acquiring new information as a process in comprehension[END_REF] after [START_REF] Chafe | Meaning and the structure of language[END_REF]" (Greenfield, 1979:165). Moreover, arguing avant la lettre for a multimodal conception of language, Greenfield and her colleagues also showed that one-word utterances combine words and gestures. Similar principles account for two-word utterances [START_REF] Baker | The development of new and old information in young children's early language[END_REF]. In these various cases, the interrelationship between young children's verbal productions and the dialogical context foreshadow the topic-comment structure.

Discourse in dialogue

Early dialogical experiences are also the first discursive ones. Even though they do not produce long stretches of monological discourse, children are involved in co-constructed or adultmediated discursive sequences. This is the case in successive one-word utterances [START_REF] Bloom | One word at a time[END_REF][START_REF] Ochs | Propositions across utterances and speakers[END_REF][START_REF] Scollon | A real early stage: an unzippered condensation of a dissertation on child language[END_REF][START_REF] Veneziano | Effects of conversational functioning on early language acquisition: When both caregivers and children matter[END_REF] when children express the same communicative intention across several utterances, with (or without) the adult's contribution. This is also the case for discourse topics and presupposition [START_REF] Ochs Keenan | Topic as discourse notion: a study of topic in the conversations of children and adults[END_REF], which are collaboratively built both on the given/new contract (H. [START_REF] Clark | Comprehension and the given-new contract[END_REF], and on specific moves within the verbal interaction. Ochs Keenan and Schieffelin's study showed that children "are often sensitive to the fact that listeners must be able to identify specific entities addressed in a discourse topic progression" (1976: 365).

Moreover, even at first, when their references are not clear enough for their addressee, young children learn to display various relevant moves to establish referents and discourse topics. [START_REF] Veneziano | Conversation and language acquisition: Unique properties and effects[END_REF] showed that in early conversations, the involvement of one participant (either the mother or the child) in successive single-word sequences contributed to the involvement of the interlocutor, and thus, to topic development.

This dialogical contingency gives rise to the first formal links between utterances [START_REF] Bloom | Adult-child discourse: developmental interaction between information processing and linguistic knowledge[END_REF][START_REF] Halliday | Development of texture in child language[END_REF][START_REF] Salazar Orvig | La reprise aux sources de la construction discursive[END_REF]. The continuity of young children's utterances rests upon two major phenomena: repetition and question-answer sequences. Firstly, repetitions are an early form of co-referential link. Secondly, co-reference is also prepared by the question-answer relation: an interrogative pronoun foresees the expected referent conveyed by the answer. Moreover, children experience topic continuity through these relations, which thereby contribute to a common topic with a new predication. These experiences, acquired in dialogue, are one of the sources of the development of referential skills.

The experience of recurrent discursive and dialogical sequences also seems to contribute to children's construction of reference in dialogue, and continuity in discourse. Several studies have highlighted this phenomenon from various perspectives. Working on Emily's early monologues, [START_REF] Levy | Monologue as development of the text-forming function of language[END_REF][START_REF] Levy | A social-pragmatic account of the development of planned discourse[END_REF] contended that the appropriation of the first "anaphoric" uses of pronouns is based on the adult's discourse sequences taken up by the child. Whereas the first pronouns used co-refer only "with the very same nouns that were previously contrasted with pronouns in monologue, and whose referential relation was observed by the child in social context" (Levy, 1999: 235), the anaphoric function of pronouns is considered to be acquired when children are able to elaborate their own speech. [START_REF] Clancy | Dialogic priming and the acquisition of argument marking in Korean[END_REF] took a complementary perspective when she adopted Bock's syntactic notion of priming [START_REF] Bock | Meaning, sound, and syntax: lexical priming in sentence production[END_REF][START_REF] Bock | The persistence of structural priming: Transient activation or implicit learning[END_REF], inter alia) and Du Bois's notion of dialogical syntax (see [START_REF] Bois | Towards a dialogic syntax[END_REF]. Her results converged with the idea that children begin taking up referring expressions in dialogical sequences before grasping their specific function. Reusing the interlocutor's forms provides the child with the experience of the appropriate contexts of use, and facilitates his/her further mapping of forms and functions. The role of priming was also indirectly considered by Matthews and colleagues [START_REF] Matthews | The effect of perceptual availability and prior discourse on young children's use of referring expressions[END_REF] to account for early, appropriate uses of referring expressions. Following [START_REF] Pickering | Toward a mechanistic psychology of dialogue[END_REF], they suggested that in the current interaction, the child shares, with the adult(s), aligned and mechanically generated situation models that do not need to be adjusted for accessibility. This alignment would allow the child to respond appropriately. Through these experiences, children would learn the manner in which referents are introduced and maintained without needing to rely on a previous assessment of availability for the interlocutor. This stance, however, is highly debatable, both for adults and children. Considering the latter, E. [START_REF] Clark | Common ground[END_REF] showed that the construction of a common ground can be accounted for by the child's specific dialogical moves and the adult's scaffolding.

Reference scaffolded by dialogue

From the studies reviewed in the previous section, we can set forth the general hypothesis that the first steps in the development of reference and referential continuity are supported by dialogue. However, we also know that young children's dialogical involvement is rather irregular [START_REF] Bloom | Adult-child discourse: developmental interaction between information processing and linguistic knowledge[END_REF][START_REF] Mctear | Children's conversation[END_REF][START_REF] Ninio | Pragmatic development[END_REF] and that children may not spontaneously ensure referential continuity. Referential development is strongly scaffolded by adults, who provide children with a "child-friendly" environment. Adults display various direct and indirect cues that guide children in identifying referents and grasping topical continuity (for a review, see [START_REF] Ateş-Şen | Children's sensitivity to caregiver cues and the role of adult feedback in the development of referential communication[END_REF]. In Western middle-class families,6 adults' responses to children's non-contingent utterances or gestures support their integration into coherent sequences. They often make sense out of children's utterances and retrospectively give them the status of dialogue initiations [START_REF] Snow | The development of conversations between mothers and babies[END_REF]. Adults can also structure their own discourse in accordance with the children's utterances [START_REF] Filipi | Conversation analysis and pragmatic development[END_REF]. In the same vein, adult reformulations of children's utterances contribute to common ground (E. [START_REF] Clark | Repetition as ratification: How parents and children place information in common ground[END_REF]. Adults can also display their misunderstanding and, in doing so, get the child to clarify her/his utterances [START_REF] Marcos | How do young children reformulate assertions? A comparison with requests[END_REF] and/or improve his/her wording [START_REF] Matthews | Two-and four-year-olds learn to adapt referring expressions to context: Effects of distracters and feedback on referential communication[END_REF][START_REF] Matthews | How toddlers and preschoolers learn to uniquely identify referents for others: A training study[END_REF]. The experience of clarification sequences gives children the opportunity to learn, in the immediate and long terms, how to adequately encode referents in contexts of potential indetermination or ambiguity. More precisely, Mathews et al. propose that it is by engaging in such processes of repair that children build up a repertoire of conversational models, learn about relevant features of their environment, gain insight into other minds, and ultimately come to fully understand why the information they provide in conversation is needed in the first place (2012: 206).

Dialogue, genre, activity, and discursive autonomy

One of the main issues in the field is how young children come to master the pragmatic and referential functions/values of linguistic units. Children's first utterances are socially situated in shared experiences and are strongly grounded in dialogue with familiar adults. Gradually, their family-based communicative experience is extended to other "social spheres" like daycare center, kindergarten, and school. They engage in more diversified, socially-situated communication settings and roles (Cook-Gumperz, Corsaro & Streeck, 1986;Duranti, Ochs & Schieffelin, 2011), which also involve changes in the adult's behaviors [START_REF] Hudelot | The use of a functional dialogic model of verbal interaction to compare how day-care workers and teachers scaffold 3-year-old children[END_REF].

Through these new settings, children's first formats [START_REF] Bruner | Child's talk: learning to use language[END_REF], which are simple, repetitive and tightly controlled by adults, develop into more complex and diversified forms that are less dependent on adult scaffolding. In other words, children's participation in dialogue becomes more and more autonomous. This process of increasing autonomy can be best observed in the acquisition of narrative skills, particularly in accounts of personal experience (de Weck, 2005). Indeed, for children, narratives are an important opportunity to gain cultural and linguistic experience, and to construct reality [START_REF] Bruner | The narrative construction of reality[END_REF].

Very early in childhood, children are exposed to stories heard, read, or jointly told. The language they hear is not only one of the here-and-now, but also one of the there-and-then, which can help them better understand, construct, and tell stories. Moreover, "this displacement of conversational topic in time and space is interesting in the first instance because of the progress it reveals in children's ability to cognitively, indeed, symbolically, represent the world" (Tomasello, 2003: 270). This is especially true for personal experience narratives. This peech genre, characterized by a there-and-then relation to the production context, and by experience-based content, is the first genre in the acquisition of discourse in which children are engaged to participate. Many studies [START_REF] Eisenberg | Learning to describe past experiences in conversation[END_REF][START_REF] Fivush | Two-year-olds talk about the past[END_REF][START_REF] Hudson | From knowing to telling: The development of children's scripts, stories, and personal narratives[END_REF][START_REF] Peterson | The who, when and where of early narratives[END_REF]; for a review, see de Weck, 2005) have pointed out a progression from total dependency on the adult -the child's participation consisting mainly of imitative repetitions of words produced by the adult -to relative autonomy at around the age of five or six. The child then becomes able to produce a discourse that is more comprehensible for an interlocutor who had no previous knowledge of the events.

Studies on narratives have provided evidence for the impact of adult involvement in joint storytelling and in the development of narrative skills in family [START_REF] Haden | Mothers' extratextual comments during storybook reading: Stylistic differences over time and across texts[END_REF][START_REF] Low | Individual differences and consistency in maternal talk style during joint story encoding and retrospection: Associations with children's long term recall[END_REF][START_REF] Macnamee | The social origins of narrative skills[END_REF] and classroom settings [START_REF] Grossmann | Enfances de la lecture: manières de faire, manières de lire à l'école maternelle[END_REF][START_REF] Sulzby | Children's emergent reading of favorite storybooks: A developmental study[END_REF][START_REF] Zucker | Preschool teachers' literal and inferential questions and children's responses during whole-class shared reading[END_REF]. For example, by responding to the child's questions and adding information, the adult allows the child to connect the different components of the story [START_REF] Nelson | Remembering and telling: A developmental story[END_REF][START_REF] Peterson | A social interactionist account of developing decontextualized narrative skill[END_REF]. This, in return, improves the way the child organizes his/her narratives and tells stories. Moreover, mothers exhibit a great diversity of styles during storytelling with their child [START_REF] Haden | Mothers' extratextual comments during storybook reading: Stylistic differences over time and across texts[END_REF]. Variations have been observed in the amount of participation by the mother and by the child [START_REF] Dickinson | Book reading with preschoolers: Co-construction of text at home and at school[END_REF], the number of comments [START_REF] Goodsitt | Interaction between mothers and preschool children when reading a novel and familiar book[END_REF], or the number of questions asked to the child [START_REF] Senechal | Age-related differences in the organization of parent-infant interactions during picture-book reading[END_REF]. Later, during reading activities in school, teachers focus on narrative comprehension by emphasizing the organization of events and their importance, and by asking questions about them. The role of questions has been investigated to a greater extent [START_REF] Florin | Pratiques du langage à l'école maternelle et prédiction de la réussite scolaire[END_REF][START_REF] Lafontaine | Quand les parents posent des questions à leurs jeunes enfants[END_REF][START_REF] Macnamee | The social origins of narrative skills[END_REF][START_REF] Nelson | Remembering and telling: A developmental story[END_REF][START_REF] Peterson | Parental styles of narrative elicitation: Effects on children's narrative structure and content[END_REF], 1994[START_REF] De Weck | Les troubles pragmatiques et discursifs dans la dysphasie[END_REF][START_REF] Pellegrini | Parents' book-reading habits with their children[END_REF][START_REF] Pratt | Mothers and fathers teaching 3year-olds: Authoritative parenting and adult scaffolding of young children's learning[END_REF]Sénéchal et al., 1995). Questions not only contribute to maintaining communication, but also to developing children's discourse skills -promoting a better structural organisation-thereby offering the child the opportunity to participate as a dialogue partner [START_REF] Lafontaine | Quand les parents posent des questions à leurs jeunes enfants[END_REF][START_REF] Danis | Shared picture-book reading: A sequential analysis of adult-child verbal interactions[END_REF]. Thus, children also acquire the skill both to differentiate important information from less relevant information from the interlocutor's point of view, and to distinguish what is new from what is given, i.e., to produce more appropriate discourse.

The trend in this acquisition can therefore be characterized as a transition from the coconstruction to the autonomous construction of narratives, at which point the child is able to produce narratives with very little support from the adult. For children with DLD, the studies have shown that these children need more support from the adult than do their typically developing peers, and that this need is observed until adolescence [START_REF] Wetherell | Narrative in adolescent specific language impairment (SLI): a comparison with peers across two different narrative genres[END_REF]. This makes it more difficult for these children to become autonomous in discourse construction.

Thus, children will face new linguistic problems, insofar as they will have to acquire the linguistic specificities of each speech genre, including expressions of reference. They must become skilled at taking into account the degree of shared knowledge with their interlocutor and his/her specific needs in order to choose appropriate referring expressions. Children also need to acquire diversified uses of referring expressions, which are dependent on the speech genre (narratives, personal-experience accounts, argumentation, informational texts; de Weck & Schneuwly, 1994) and the modality (oral vs. written; e.g., [START_REF] Jisa | Developmental perspectives on the role of French on in written and spoken expository texts[END_REF][START_REF] Rosat | A propos de réalisations orale et écrite d'un texte argumentatif[END_REF].

Pronouns, for instance, are more often used in oral narratives to mention a given referent [START_REF] De Weck | La cohésion dans les textes d'enfants. Etude du développement des processus anaphoriques[END_REF].

Moreover, the kind of shared activity also influences the participants' language productions. This influence can be observed for various domains: syntactic structure, lexical resources, and the pragmatic aspects of the current interaction, for adults and for children of all ages [START_REF] Altinkamis | When context matters more than language: Verbs or nouns in French and Turkish caregiver speech[END_REF][START_REF] De Weck | Troubles dysphasiques. Comment raconter, relater, faire agir à l'âge préscolaire[END_REF][START_REF] Gee | On the use of will and gonna: Toward a description of activitytypes for child language[END_REF][START_REF] Heurdier | Usages syntaxiques et dialogue parent-enfant. Etude de dyades mèreenfant et père-enfant dans deux activités ludiques[END_REF][START_REF] Kern | Contextes de production et LAE en français: caractéristiques pragmatiques et syntaxiques[END_REF][START_REF] Leaper | The relationship of play activity and gender to parent and child sex-typed communication[END_REF]. This suggests that during dialogue, dyads co-elaborate their utterances in relation to the activity being carried out. However, very few studies have been conducted on the relation between referring expressions and the current activity (Salazar Orvig, Marcos, Heurdier & da Silva-Genest, 2018;[START_REF] Kern | Effet du type de support imagé sur la production du récit chez l'enfant[END_REF].

The impact of the activity can also be observed on DLD children's use of referring expressions.

In a free-play activity, for example, they do not produce more null forms than their peer typical children [START_REF] Thordardottir | Specific language impairment in French-speaking children: Beyond grammatical morphology[END_REF], whereas differences can be observed on elicitation tasks (e.g., [START_REF] Grüter | Comprehension and production of French object clitics by child second language learners and children with specific language impairment[END_REF].

Thus, becoming autonomous in discourse production involves the development of different skills: to use referring expressions children have to take into account several aspects of the socio-discursive context (speech genre and modality, activity, relevant content, new vs. given information, etc.). But very few studies have looked into the relation between referring expressions and these aspects. Some chapters of this book deal with these issues.

The need for a multidimensional dialogical perspective

This overview of the main issues that arise when studying the acquisition of referring expressions shows that this developmental process cannot be understood from a single perspective alone, such as by considering purely morphological or purely syntactic aspects, as many studies do. For instance, studies on fillers typically consider only the phonetic/morphological interface, without raising the question of the possible functional aspects of these forms that children add to nouns and verbs. Also, studies on the expression of subjects in several languages have shown that the alternation of overt and covert forms cannot be accounted for solely in syntactic terms, even in non-null subject languages [START_REF] Allen | Formalism and functionalism working together? Exploring roles for complementary contributions in the domain of child null arguments[END_REF].

The acquisition of the paradigms of pronouns and verb inflections goes together with the appropriation of the conditions of expression of subjects and the choice of strong versus weak forms. At the same time, usage-based studies have shown that children take up the most frequent patterns found in the adult input (Cameron-Faulkner, [START_REF] Cameron-Faulkner | A construction based analysis of child directed speech[END_REF].

Research has shown that both distributional and statistical learning strongly contribute to the first uses of pronouns, frequently associated with verbs. However, this is not in contradiction with the discourse-pragmatic explanation. Frequent patterns in the input are frequent because they correspond to means of achieving frequent social acts and conveying recurrent meanings.

They have socio-pragmatic raisons d'être [START_REF] Lieven | Usage-based approaches to language development: Where do we go from here?[END_REF][START_REF] Tomasello | The cultural origins of human cognition[END_REF], and they are embedded in frequent formats/scripts and activities [START_REF] Nelson | Young minds in social worlds: Experience, meaning, and memory[END_REF]. Nelson [START_REF] Levy | Words in discourse: a dialectical approach to the acquisition of meaning and use[END_REF][START_REF] Nelson | Young minds in social worlds: Experience, meaning, and memory[END_REF][START_REF] Nelson | Developing a socially shared symbolic system[END_REF] argued that new forms are acquired along with their distributional features because children experience them in specific language games (following Wittgenstein 1953; see also [START_REF] Nelson | Wittgenstein and contemporary theories of word learning[END_REF]. At first, children grasp the overall contexts in which grammatical forms are used. They reproduce those contexts without necessarily mastering the adult value of the form. In this way, the semantic aspect of a grammatical word is thus built gradually. Furthermore, frequency can be overridden by pragmatic factors. [START_REF] Ochs | The impact of language socialization on grammatical development[END_REF], for example, showed that in Samoan language acquisition, the use of imperatives by children depends less on their frequency in the input than on the children's awareness of the social indexicality of the verb. Similar observations can be made about the use of personal pronouns (Salazar Orvig, 2017).

Our stance is that beyond a statistical view of the input, the dialogue and dialogical continuity constitute a driving force that can affect the way children grasp the use of referring expressions. This is because dialogue provides the child with the actual experience of referential continuity -which he/she experiences in various socio-discursive contexts, such as in conversation, games, or shared reading -or because adults scaffold children's use of referring expressions.

Our contention is that the acquisition of referring expressions depends on the interaction of these various factors, both formal and functional, and that the construction of forms, the emergence of meanings, and the appropriation of uses cannot be understood without addressing their interaction. Because children learn the language through socially-situated interactions driven by activities and scaffolded by adults, it seems to us that referring expressions, as a pivotal phenomenon in language acquisition, cannot be properly approached without taking their multiple dimensions into consideration. This constitutes both a theoretical and a methodological challenge.

Dialogical approach: methodological implications

Considering the challenges mentioned above, our position in this volume is that adopting a dialogical approach may shed new light on the topic of the acquisition of referring expressions.

In this approach, the focus is both on socio-discursive contexts and on dialogue -in other words, on the forms and functions of utterances in the co-construction of discourse. However, in the study of referring expressions, it is methodologically impossible to simultaneously and equally embrace all formal and functional aspects. It is possible to adopt a multidimensional methodological and interpretive framework aimed at grasping the complexity of reference acquisition, even when a specific issue is being addressed. This framework requires examining referring expressions in ecological, dialogical situations that are as close as possible to the child's communicative experiences.

Acquisition of referring expressions (as a construction process) depends on the forms and uses that children experience. Children gradually seize these forms-in-use as models, in dialogue.

The forms-in-use are conditioned by the interactional setting (interlocutors, places, goals), the activity, and the speech genre.

The following chapters report the main results of a multi-year research program entitled Acquisition of referring expressions in dialogue: a multidimensional approach (DIAREF, see footnote 1), a collaboration of numerous researchers. The DIAREF studies were all guided by the dialogical approach described above. In this section we present our main methodological choices for selecting and analyzing the data. Section 3.1. presents the various corpora on which the studies were based, and section 3.2., the various formal and functional aspects of our multidimensional approach.

Varied corpora

Data were all collected during meaningful shared activities [START_REF] De Weck | Options théoriques et choix méthodologiques pour l'étude des capacités discursives des enfants d'âge préscolaire[END_REF] in which a child is often interacting with an adult (dyads) -usually the mother, sometimes the father, but also with a small group of children and a teacher [START_REF] De Weck | Options théoriques et choix méthodologiques pour l'étude des capacités discursives des enfants d'âge préscolaire[END_REF]. This type of corpus allows us to observe the mutual verbal and non-verbal influences of the participants along with the impact of dialogue itself. This makes it possible to understand how adults scaffold children's language [START_REF] Wood | The role of tutoring in problem solving[END_REF] and how children react to adults ' verbal and non-verbal actions (de Weck & Salazar Orvig, 2019). It also allows the elucidation of the implicit models children are confronted with when interacting with adults, in addition to allowing us to potentially assess the similarities and differences in the child and adult uses. Natural situations with which children are familiar seem the most favorable to these types of analyses.

We compiled sets of data that had already been collected by our research teams as part of other research projects 7 . These data were supplemented by two specific sets of data collected for the purpose of the DIAREF project. The corpora differ in several respects, which are briefly presented below 8 .

Our data cover a variety of contexts in family and in nursery-school settings. They involve children between the ages of 1;7 and 7;5. There are two subgroups in the family corpora. The first group contains children aged 1;7 to 2;6 (toddlers), who were videotaped while interacting with their mothers in everyday home activities and in quasi-natural situations where the researcher brought specific toys or books. The second group contains older children ages 3 to 7 years, who were videotaped while interacting with their mothers in quasi-natural situations (joint storytelling and symbolic play). In the second group, a subgroup (ages 5 to 7 years) have developmental language disorders. The nursery-school data (ages 2 to 6 years) were collected from four different classes in which a teacher is interacting with a small group of pupils during familiar joint storytelling. Some of the children participated in this same activity both at school and with their mothers. This gave us comparable data in two different social settings, which is one of the novelties of some of our studies. In order to compare the family and school settings to an experimental one, we collected data from young women telling an experimenter the same story used for the child-mother data. The studies reported in this volume selected relevant data sets from the corpora, depending on the specific issues addressed. Similarly, not all of the data from the various activities involving a given dyad were used. Details regarding data selection are found in each chapter.

Formal and functional aspects in a multidimensional approach

Taking this multidimensional approach to the development of reference, we aim to link the formal and functional aspects of language acquisition. This involves two stages, a descriptive phase and a subsequent analytical phase. In the descriptive phase we identified all referents in the participants' speech, as well as all the corresponding nominal expressions. The linguistic expressions were described in terms of the following dimensions:

 Grammatical categories: all expressions were categorized from the grammatical standpoint (as nouns, pronouns of the different types, and dislocations, as well as null forms and fillers).

 Phonetic and phonological features were considered for the study of fillers, protodeterminers, and proto-pronouns, and their development into adult forms.

 Also, in one case, the prosody (presence/absence of an intonation contour) of selected referring expressions was analyzed.

In the analytical phase, we studied the impact of formal factors and functional factors (referential, socio-discursive and dialogical) on the use of the various referring expressions.

The formal factors included:

• Syntactic factors: the syntactic function of the referring expression, mainly the subject, and verb frames in which the referring expression occurred.

• Distributional factors: the lexical form associated with the referring expression and, for dislocations, the pre-or post-verbal position of the dislocated term.

The underlying assumption was that the acquisition of verb and noun morphology should not be dissociated from the construction of reference.

The referential factors included:

 The type of referent: a) the difference between referring to entities and referring to discourse participants [START_REF] Benveniste | La nature des pronoms[END_REF], and b) in narratives, the characteristics of entities: animacy (animate vs. inanimate referents), and primacy (main vs. secondary referents).

• The referent's attentional and discursive status, which reflect its accessibility and/or givenness: new, activated, discourse-given, or reintroduced after a thematic change.

• The position of the referring expressions in the referential chain: whether the referent is mentioned for the first time, maintained, or reactivated after several turns without being mentioned. This perspective is more relevant to narratives than is the attentional and discursive status because during joint storytelling joint attention is necessarily achieved.

The socio-discursive and dialogical factors included:

• The activity being carried out (storytelling, play, snack, etc.).

• The influence of speech genre (narrative, description of actions or states, labelling, justification, negotiation, explanation, etc.).

• The social status of the child's adult interlocutors (mother, teacher), the social setting (home, school).

• The interactional setting, when we consider adult discourse: the relevance of the addressee, that is the person for whom the discourse is formulated (TD or DLD child, adult experimenter).

• The modality of participation in the dialogue, and more precisely the relation between the utterances of the interlocutors (continuity, contrast, opposition, reiteration).

• The influence of the adult's discourse on the child's use of referring expression.

Depending on the issue addressed in each study, more specific analyses were conducted to take into account the interaction between some of the above factors.

The role of these different factors must be examined both separately and together, in order to account for the diversity and complexity of the referential system, which cannot be looked at only by itself. We assessed the impact of the factors examined by using statistical tests. Our data, as it is often the case with empirical data drawn from naturally occurring situations, did not satisfy the minimal assumptions for a parametric test (normal distribution, homoscedasticity, and variance equality), so we used non-parametric tests which allowed us to compare distributions or groups. In most of the chapters, we explored the impact of both formal and functional factors using mixed-effect binomial regressions, including random-effect variables such as participants and sessions. Interaction between factors was further assessed using binary partition trees drawn with the ctree function included in the "party" R package [START_REF] Hothorn | Partykit: A modular toolkit for recursive partytioning in R[END_REF].

This book

The book is divided into two parts, which build on each other: The first part deals with reference and grammar, and the second part deals with the role of communicative experience in the acquisition of reference. Together, they investigate the grammatical and communicative factors at play in the uses of referring expressions in their various facets.

In Part I, "Reference and grammar", the chapters present children's uses of referring expressions, both in terms of their formal features and in terms of the pragmatic and discursive factors that affect their choice in discourse. This part opens with a discussion by Yamaguchi, Salazar Orvig, Le Mené, Caët, and Rialland (Chapter 2) on the need to include the protomorphological phenomenon of fillers in studies on referring expressions and their role as precursors of grammatical units. Yamaguchi and colleagues address several issues covering a wide range of formal and functional aspects. After identifying the various prenominal and preverbal forms and assessing the weight of transitional forms for each of these two positions, the chapter explores the impact of different factors on the form and use of fillers, including the specificity of their phonological realization, their distributional properties, and sensitivity to their potential referent. The authors present arguments for considering filler syllables as early grammatical units in formation.

Da Silva-Genest, Marcos, Salazar Orvig, Caët, and Heurdier (Chapter 3) address the use of referring expressions by young children in naturally occurring dialogues, whereas Rezzonico, Vinel, de Weck, Hassan, and Salagnac (Chapter 4) examines the use of referring expressions by older children in a storytelling activity. Da Silva-Genest and colleagues focus on three strong forms (nouns, strong demonstrative pronouns, and strong personal pronouns) and three weak forms (clitic personal pronouns, null forms and fillers). They examine the impact of linguistic development, type of referent (participants vs. entities), syntactic function, and the referent's attentional and discursive status on the use of these six referring expressions, thus exploring the intertwining of morphological, syntactic, and pragmatic development. Rezzonico and his colleagues focus on the way older children produce referring expressions when engaged in a joint storytelling activity with their mothers. The children's use of referring expressions is analyzed in terms of five factors: the referent's characteristics (animate vs. inanimate, primary vs. secondary referents), its grammatical category, its syntactic function, its discursive status (position in the referential chain), and the child's chronological age. By assessing both the individual effects and the interaction of these four factors, these authors identify the network of factor interactions, which can differ for nouns and third-person pronouns.

In Chapter 5, Rezzonico, Bernasconi, de Weck, da Silva, and Jullien deal with the uses of referring expressions by children with developmental language disorders, as compared to typically developing children, in a shared storytelling activity with their mothers. In particular, subject omissions and the diversity of the types and forms of pronouns are investigated in relation to the position in the referential chain and the syntactic function. The results bring new insights to the discussion on the relation between morphosyntactic difficulties and discursive and pragmatic dynamics. Finally, Klein, Jullien, and Fox (Chapter 6) explore the interaction of formal and pragmatic factors in syntactic constructions (dislocations and verb frames) and the intonation contour of the referring expressions used in these constructions. On one side, they examine the extent to which young children's sensitivity to the position in the referential chain, as compared to their adult interlocutor, is expressed in their syntactic choices, (e.g., dislocations), and in variations in the intonation contour. On the other side, they assess the respective weights of syntactic constraints and the position in the referential chain on the use of referring expressions and their intonation contours when considering verb frames.

Part II of this book further explores children's early pragmatic skills by considering "the role of communicative experience" in its functional dimension. This part addresses some of the main aspects of this experience, from child-directed speech and dialogue to the role of speech genre and the current activity. More specifically, the authors examine the models of referringexpression use that children experience in different interactional and social settings, as well as the influence of speech genre and activity on the choice of referring expressions by both the children and the adults. The interaction between the adult and child productions are considered within the dynamics of the dialogue.

In Chapter 7, Marcos, Salazar Orvig, da Silva-Genest, and Heurdier explore the potential influence of adult input and dialogue in young children's uses of referring expressions. They address this issue from different angles. After comparing the children's and the adults' uses of referring expressions, the authors assess the potential adaptation of the adults' uses to their children's linguistic development. They then go on to explore the influence of the adult's forms on the child's uses (i.e., priming), considering the position of the referring expressions in dialogical moves as an alternative account. Finally, they examine the way dialogical sequences scaffold the emergence of children's referential skills. In Chapter 8, Hassan, de Weck, Rezzonico, Salazar Orvig, and Vinel focus more specifically on the impact of the interactional setting on the adult's uses of referring expressions during storytelling. With the aim of understanding the models children are exposed to, these authors explore not only the implications of co-constructing a narrative with a child as compared to telling the same story to an experimenter, but also the impact of co-constructing a narrative at home as compared to telling a story with a group of pupils at school, or co-constructing a narrative with a typically developing child as compared to co-constructing the narrative with a child with developmental language disorders. The next two chapters further explore the impact of the interactional or discursive context on the use of referring expressions. De Weck, Hassan,Heurdier,Klein,and Salagnac (Chapter 9) attempt to account for the relative effects of two factors -the activity undertaken by the participants in the interaction and the social setting (home or school) -on toddlers' and older children's use of referring expressions in dialogue. The authors focus on the following activities: daily routines, activities based on pictorial material, playing with toys, and joint storytelling. The comparison of the two social settings is conducted only for the joint storytelling activity. In all cases, the use of referring expressions is analyzed with respect to their position in the referential chain. This chapter provides a weighted analysis of the pragmatic and interactional factors involved. Finally, Vinel, Salazar Orvig, de Weck, Nashawati, and Rahmati (Chapter 10) examine how speech genres influence the choice of the referring expressions in toddlers' and older children's productions. Speech genres are considered at two levels: the discursive-sequence level (narrative discourse or here-and-now discourse) and the utterance level (such as description, explanation, labelling, etc.). This chapter assesses the relative weight of speech genre with respect to the position in the referential chain, in the productions of the two groups of children during a picture-based activity. The implication of the interactions between these factors is discussed in view of gaining a better understanding of the acquisition paths of young children.

Lastly, in Chapter 11, Salazar Orvig and de Weck undertake a general discussion of the results presented in Chapters 2 to 10. These results point out the strong interaction of the formal and functional facets of children's acquisition and use of referring expressions. As a whole, the chapters highlight the need to consider the dialogical and socio-discursive dimensions of this process, and not just the formal and cognitive ones. Through its journey, the book brings out a set of arguments in favor of a dialogical and interactionist account of children's referential development.

  Thus, we still need to gain knowledge of how early and late skills grow into adult-like uses through the child's cognitive and social development. Concerning the cognitive aspect, several studies have looked more specifically at the development of theory of mind[START_REF] De Cat | Egocentric definiteness errors and perspective evaluation in preschool children[END_REF][START_REF] Gundel | Children's use of referring expressions in spontaneous discourse: Implications for theory of mind development[END_REF][START_REF] Gundel | Children's use of referring expressions: some implications for theory of mind[END_REF][START_REF] Schafer | Imagining Articles: What a and the can tell us about the emergence of DP[END_REF][START_REF] Van Hout | Comprehension and production of definite and indefinite noun phrases in English preschoolers[END_REF] and executive functions, like working memory and cognitive control skills, in order to account for children's referential performance in experimental settings[START_REF] De Cat | The cognitive underpinnings of referential abilities[END_REF][START_REF] Nilsen | The relations between children's communicative perspective-taking and executive functioning[END_REF][START_REF] Serratrice | Individual differences in the production of referential expressions: The effect of language proficiency, language exposure and executive function in bilingual and monolingual children[END_REF]

7

  These research projects include the Colaje project (grant ANR-08-COMM-0021), Morgenstern & Parisse (2012); Développement du Langage et de la Communication entre deux et trois ans: influence du mode d'accueil (funded by the French Caisse Nationale d'Allocations Familiales, Marcos, Salazar Orvig, Bernicot, Guidetti, Hudelot & Préneron (2004)); Les interactions mère-enfant en situation logopédique (Swiss National Science Foundation grants Nos. 100012-111938 and 100012-124744/1); Nashawati's Ph. D. dissertation (2010); Développement des conduites dialogiques (Salazar Orvig, 2003); Comparison between mother-child communication and father-child communication (Kornhaber-Le Chanu & Marcos, 2000); Yamaguchi-Adrien project (part of Leonard project, grant ANR-JC05_47273 and Yamaguchi's Ph. D. dissertation, 2012).8 See Appendix 1 for a detailed presentation of all corpora.

With the exception of Chapter 2, and, in a very limited way, of Chapter 8, the development of determiners is not addressed in this book.

Let's note that Ariel's and Gundel's approaches cannot be assimilated with each other. Ariel points to the conditions of the retrieval of the antecedents of referring expressions in various contexts[START_REF] Ariel | Accessing noun-phrase antecedents[END_REF] whereas[START_REF] Gundel | Reference and accessibility from a givenness hierarchy perspective[END_REF][START_REF] Gundel | Cognitive status and the form of referring expressions in discourse[END_REF] considers the values associated to the various referring expressions. These two approaches nevertheless seem to be considered similar in many papers.

The density of a grammatical category is the proportion of the occurrences of that category relative to the number of words or verbs in the discourse analyzed.

The situation can be very different in other cultures where adults are not expected to act in this way and therefore do not interpret the children's non-adult like utterances (see[START_REF] Ochs | The impact of language socialization on grammatical development[END_REF].

Acknowledgements

We thank the internal reviewers, as well as Shanley Allen and Evan Kidd, for their helpful comments, and the team of the DIAREF project (Acquisition des Expressions Référentielles en dialogue: approche multidimensionnelle) for their contribution to the scientific and methodological discussions. A thanks goes to Vivian Waltz for her thorough and rigorous English proof-reading

Funding

This research was made possible thanks to the grants from the ANR Agence Nationale de la Recherche (French National Agency for Research) and the FNS Fonds National de la Recherche Scientifique Suisse (Swiss National Science Foundation) for their funding (Grants n° ANR-09-ENFT-055; FNS 100012-111938 and 100012-124744).